Report
on
Coastal Zone Vulnerability and Adaptation Assessment,
Aden Governorate, Republic of Yemen
(As a part of Second National Communication)
Prepared by: Coastal Zone Team,
Mohammed M. Abubakr, (Team Leader), Mohammed Ali Al Saafani, Hisham M. Nagi,
Ahmed Hajer, Adel M. Alhababy,
Table of Contents
1.
1.1
1.2
1.3
1.4
1.5
2.
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
3.
3.1
3.2
3.3
3.4
3.5
3.6
4.
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
4.12
5.
5.1
5.2
5.3
5.4
6.
6.1
6.2
7.
Table of Contents…………………………………………………………………..
List of Tables…………………………………………………………………….....
List of Figures…………………………………………………………...................
Abbreviations……………………………………………………………………....
Acknowledgments………………………………………………………………….
Executive Summary………………………………………………………………..
General Introduction…………………………………………………….................
Introduction………………………………………………………………………...
Research Context – Assessing Coastal Vulnerability……………………...............
Current Approaches and Limitations………………………………………………
Research Purpose and Objectives………………………………………………….
Data Used…………………………………………………………………..............
Study Area Characters…………………………………………………………...
Coastal Physical Environment……………………………………………..............
Meteorology………………………………………………………………..............
Oceanography………………………………………………………………………
Study Area: Governorate of Aden………………………………………………….
Population and Administrative Divisions………………………………………….
Coastal and Marine Environment…………………………………………………..
Review of SLR in Aden……………………………………………………………
Selection of Scenario……………………………………………………………….
Potential Impacts of Sea Level Rise……………………………………...............
Erosion……………………………………………………………………...............
Inundation…………………………………………………………………………..
Saltwater Intrusion…………………………………………………………………
Increasing Flood Frequency Probability…………………………………………...
Ecological Impacts………………………………………………………………...
DIVA Model………………………………………………………………………..
Socioeconomic Impacts…………………………………………………...............
Houses and Residential Area……………………………………………………….
Land Value…………………………………………………………………………
Saltpans Area……………………………………………………………………….
Educational Structures……………………………………………………...............
Health Structures…………………………………………………………...............
Roads……………………………………………………………………………….
Electricity…………………………………………………………………..............
Water and Sanitation Networks…………………………………………………….
Communications Network………………………………………………………….
Tourism Structures…………………………………………………………………
Aden International Airport…………………………………………………………
Other Constructions………………………………………………………...............
Adaptation Strategies……………………………………………………..............
The Need for Adaptation…………………………………………………...............
Adaptation to Climate Change……………………………………………..............
Adaptation Strategies and Plans……………………………………………………
Integration of the Adaptation into National Policy and Planning………………….
Conclusion and Recommendations………………………………………………
Conclusion………………………………………………………………………….
Recommendations………………………………………………………………….
References…………………………………………………………………………
ii
ii
iii
iii
iv
v
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1
2
2
5
6
7
8
9
10
12
15
18
19
26
28
29
30
33
34
43
46
49
53
56
59
59
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61
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62
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64
65
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74
78
79
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List of Tables
2.1
2.2
2.3
2.4
3.1
3.2
4.1
4.2
5.1
5.2
Plant species listed in Al Hiswah wetland………………………………………...
List of common bird’s species associated with Aden wetlands…………………...
Fishers and fishing boats numbers………………………………………………...
Coastal areas recommended for special management in Aden due to their
biological, environmental or recreational importance…………………………….
Sea level rise scenarios for Aden Governorate……………………………………
Summary of well field production capacity and water level average drops up to
the year 2001………………………………………………………………………
Areas which will be subjected to inundated in Aden Governorate………………..
Expected economic losses due to sea level rise (33cm) in Aden Governorate……
Adaptation measures in coastal areas to be highlighted in national
communications of Yemen………………………………………………………..
The main biophysical effects of relative sea level rise, including examples of
possible adaptation responses……………………………………………………..
24
25
26
27
34
38
60
63
68
71
List of Figures
1.1
2.1
2.2
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
4.1
4.2
4.3
4.4
Map of the study area……………………………………………………………...
Schematic diagram showing the pattern of the mesoscale eddies in the surface
circulation in the Gulf of Aden. The acronyms A and C represent anti-cyclonic
and cyclonic eddies respectively…………………………………………………..
Climatology of Air temperature in Aden, created from monthly values from
1992-2009…………………………………………………………………………
Saltwater intrusion in a coastal aquifer……………………………………………
Base map of Delta Tuba and Delta Abyan………………………………………...
Contour lines of saltwater intrusion in (a) Abyan delta, and (b) Tuban delta…….
Resistivity cross-section: Line B Abyan delta…………………………………….
Resistivity cross-section: Line D………………………………………………….
Resistivity along the eastern side of section E in Tuban delta…………………….
Resistivity cross-section: Line G Tuban delta…………………………………….
Khor Bir Ahmed shown in recent Google image, with compare with its situation
in an aerial photography of 1975………………………………………………….
Output from DIVA model…………………………………………………………
Map of important sectors in the Governorate of Aden……………………………
Map of Aden Governorate showing the expected inundated area due to the SLR
of 33 and 60 cm……………………………………………………………………
Map of the most sensitive areas of the Governorate, which are vulnerable to
inundation due to SLR of both 33 and 60 cm……………………………………..
3D view of Aden Governorate shows the areas to be inundated by SLR of
33cm……………………………………………………………………………….
iii
5
13
18
36
37
39
39
41
41
42
47
52
55
56
57
58
Abbreviations
AR4
Fourth Assessment Report
CD
Chart Datum
CZMS
Coastal Zone Management Subgroup
DIVA
Dynamic Interactive Vulnerability Assessment
EEZ
Exclusive Economic Zone
EPA
Environment Protection Authority
ERT
Electric Resistivity Tomography
EU DINAS-COAST
GDP
Dynamic and Interactive Assessment of national, regional
and global vulnerability of Coastal Zones to Climate Change
and Sea-level Rise
Gross Domestic Product
GIS
Geographic Information Systems
GVA
Global Vulnerability Assessment
HHT
Highest High Tide
ICZM
Integrated Coastal Zone Management
INC
Initial National Communication
IPCC
Intergovernmental Panel of Climate Change
MSL
Mean Sea Level
MSRRC
Marine Science Research and Resource Center
NAPA
National Adaptation Programme of Action
NE
Northeast
NGOs
Non Governmental Organizations
NWSA
National Water Supply and Sanitation Authority
PaR
Population at Risk
SC
Specific conductance
SLR
Sea level Rise
SNC
Second National Communication
SST
Sea Surface Temperature
SW
Southwest
SWL
Scenario Water Level
UNEP
United Nations Environment Program
UNFCCC
United Nations Framework Convention on Climate Change
iv
Acknowledgment
In the first place and for most, the coastal zone team would like to thank the
Environment Protection Authority particularly eng. Mahmoud Shidiwah, Chair, for
supporting the execution of this study. We warmly thank Mr. Anwar Noaman Head
of Climate Change Unit, CDM-DNA Secretariat, for being critical as well as
supportive, and whose suggestions, questions and patient eased and made our work
enjoyable. Special thanks extend to the steering committee for their guidance &
suggestion and to Mr. Faisal Al Sa’adi of the Climate Change Unit.
Distinctive appreciations are due to Mr. Faisal Al Tha’alabi, Chair of EPA- Aden, Mr.
Gameel Al Qadassi of Aden Governorate Office, Mr. Ahmed N. Al-Sarary and
Munassar A. Hassan of the Geological Survey & Mineral Resource Board-Aden, Mr.
Gamal Bawazeer of the Aden Wetland Project and to Mr. Mahfoud M. Qasem of the
Maritime Authority. We also would like to thank Mr. Badr N. Al-Rosy and Ahmed
Masheeb for their help during the field work.
Finally, and not least important for us to express our gratitude to the hospitality,
kindness, and openness of all interviewees and peoples met in Aden and Sana’a
during the execution of this study.
v
Executive summary
The Republic of Yemen is located at the southwestern edge of the Arabian Peninsula
between 12o to 20o north and 41o to 54o east. The coastline of Yemen is more than
2300 kilometers long; the Gulf of Aden takes up about two thirds of this, with the
remainder bordering the Red Sea. The Yemeni coastal line along Gulf of Aden and
Arabian Sea is approximately 1400 km long, extending from Bab el Mandab at the
west to Ras Darbat Ali at the east. The landmasses surrounding the Gulf of Aden are
characterized by hot and dry climates with little vegetation. Strong winds blowing
across these areas often carry sand and dust. The Gulf of Aden coast is dominated by
the Indian Ocean monsoon system. Winter monsoon continue from November to
March with northeasterly wind.
The Second National communication (SNC) (present study) conducted taking into
consideration the good practice and lessons learnt from the INC and other climatechange related projects. The coastal zone sector was studied and identified under the
National Adaptation Programme of Action (NAPA), as one of the most vulnerable
areas to climate change in Yemen. NAPA process focuses on the national and shortterm implications of climate change on (i) water resources, (ii) agriculture, and (iii)
coastal zones. SNC works at the level of specific geographical hotspots, addresses
long-term climate risks and adaptation on these three sectors. The priority area,
targeted by the SNC coastal zones team, is the coastal zone of Aden Governorate, as a
new area of study.
This study describes the vulnerability assessment of the impact of sea level rise (SLR)
on the coastal area of the Governorate of Aden, and discussed the possible adaptation
options. With the identification of the scenarios for accelerated sea level rise, the
study identified the possible impacts on both the coastal habitats and socio-economic.
This includes identification of biophysical impact of SLR on the coastal area and the
socioeconomic impacts.
The study approach to assess climate change impacts was designed by adopting a
range of assessment methods including stakeholders involvement, and the use of
expert judgment. The stakeholders were involved in the assessment by discussions
and responses to a questionnaire about the vulnerability and adaptation to sea level
vi
rise in Aden Governorate. Other tools were also used, such as geographic information
systems (GIS) and Dynamic Interactive Vulnerability Assessment (DIVA). Regarding
the modelling, DIVA model was used to give preliminary idea about the vulnerability
of the coastal area to climate change and sea level rise.
Two plausible future sea-level rise scenarios for the Governorate of Aden coastal
region are adopted. Values are in meters above main sea level (MSL), which is 1.4 m
above CD (Chart Datum) for Aden. Scenarios are based on (i) observed rates for
Aden mean sea-level rise, 3.3 mm/yr, and (ii) extreme sea-level rise rate of 5.9 mm/yr
at highest high tide (HHT) is included for an extreme scenario. Scenarios of 0.33m,
and 0.60m SLR over this century were assumed.
Bruun rule used to estimate the erosion along the coastal area of the governorate due
to SLR based on the parameters of the study area. The recession of the shoreline was
estimated at about 23 m and 41 m along the eastern part of the study area
(Khormaksar till Al Alam), for rise in sea level of 0.33 m and 0.6 m, respectively, and
about 18 m and 33 m, respectively, along the western shoreline (Foqm Bay). This was
translated to a potential land loss along the entire shoreline of the pilot area (length 23
km) about 48 and 86 ha, respectively. This loss of the sandy beaches will affect the
tourism and recreation activities in coastal communities, especially along
Khormaksar, Glod Moor, Foqm Bay Beaches, and the rest of the sandy beaches.
The total land area that would be inundated under the various climate change
scenarios is substantial. With the proposed sea level rise of 33 cm, the percentage of
the inundated area is 43 Km2, which represents 5.7% of the total area of Aden
Governorate (about 750 km2). The inundated area would increase to about 45 km2
(6%) for SLR of 60 cm. Inundation will unevenly affect Aden Governorate coastal
area. Khormaksar, Al Tawahi Bay, the coastal beach between Khormaksar and Al
Alam (Abyan Coastal Beach), Aden lagoons and wetlands are the most affected
regions. About 3.90 km2 will be inundated in the dens populated area of Khormaksar,
Al Mansoora, and Al Mua’alla Districts for SLR of 33 cm, while 4.35 km2 would be
inundated for SLR of 60 cm.
The saltwater intrusion into Delta Abyan, extends to a distance of 4 km of the
southeastern portion of the delta. It appears that the further inland position of the
vii
shallow portion of the saltwater intrusion front on the east side of the Abyan area is
related to incursion of saltwater along unconsolidated, more permeable sediments.
The extent of the saltwater intrusion will extend further inland by rising sea level, for
the proposed scenarios of 0.33 and 0.6 m. The interface between the saltwater and
freshwater will extend 160 m and 240 m inland and 16m and 24 m upward,
respectively, affecting the fresh water aquifer in that region.
In Tuban Delta, the contours of saltwater intrusion are approximately parallel to the
coastline, about 10 km inland on the eastern side of the delta. Bir Nasser well field is
located along the eastern side of the delta, where possible brackish water deeper than
150 m is threatening the water quality of this water field. With the rising sea level of
0.6 m, the level of the intrusion could rise to the well depth and affect the main source
of ground water of Aden Governorate.
Along the section of Bir Ahmed well field, the first 3000 m from the shoreline are
characterized by a saltwater intrusion. The saltwater intrusion front dips northward.
Bir Ahmed well field produces groundwater at a maximum depth of 64 m. The layer
deeper than that may contain brackish water as indicated from low resistivity.
Increased conductivity over time may reflect increasing intrusion of saline water from
the ocean, or up-coning if a wedge of saline water has intruded under the well field.
This increasing in conductivity will be accelerated due to sea level rise.
Sea-level rise and changes in coastal population are unconstrained. In all scenarios,
there are large potential increases in coastal population, which is reinforced by the
assumption of coastal attraction of population. The current population of Aden
Governorate according to the 2004 Census is 598,419, and by 2030, it would increase
to 1.5 million (considering a growth rate of 3.53% for Aden population). Relative sea
level rise simply displaces the extreme water levels upwards. Following the GVA
steps, risk is measured using the average number of people flooded per year. For the
first scenario the future storm surge will be 2.81 m above the MSL, resulting in the
height of the maximum flood level of 4.24 m for the first scenario and 4.50 m for the
second scenario above CD. Accordingly, the flood prone area, the area contained
between the coastline and the maximum flood level would be vulnerable to storm
surge flooding, which could cover most of the coastal plain of Aden Governorate,
including Khormaksar, Al Mansoorah, Al Mua’alla, Al Buraiqah, the beach between
viii
Ras Umran and Foqm. This would effects about 50% of the populated area of Aden
Governorate, where the present average population density considering that the
population is equally distributed, is 800/km2. The population density is expected to
increase to 2100/km2 in 2030, considering growth rate of 3.53%.
DIVA model was used to investigate the effect of sea level rise in the costal area of
the Gulf of Aden as an integral way. The output from DIVA was compared with the
vulnerability assessment approach used in this study. The output from the model
shows underestimated result compare with the output of the vulnerability analysis.
The under estimation of the impacts by DIVA model was due to the coarse resolution
of the input data and also due to the fact that the division of the coastal region into
coastal segments was not representing the actual situation. In despite of the
underestimation of the impact by DIVA model, it also show the risk of the sea level
rise on the coastal area of Aden Governorate.
The total socio-economic loose include loss in the infrastructures, livelihoods. Total
of the houses at risk of inundation under the first scenario are about 11462 houses,
which represent about 11.88% of the total number of houses in the governorate. The
number of families liven in these houses represents about 11.5% of the total families
of the governorate with about 68843 people will be affected. This represents about
12% of the total population of the governorate according to 2004 census.
It has been found that the grand total economic losses due to sea level rise by 33cm
and 60cm are equal to 410,233 and 459,461 million YR, respectively. As the average
annual growth of different establishments in Aden Governorate is increasing by 1.5%,
the expecting economic losses in 2050 are expected to reach approximately 767,136
million YR
Identification of adaptation options was carried out by designing and administering a
questionnaire based on direct communication with stakeholders in vulnerable areas.
An adaptation decision matrix approach based on cost effectiveness of adaptation
measures was also evaluated. The following attributes were found to be the most
important: expenses, net benefits, environmental impacts, robustness and flexibility,
chance of success, feasibility, and fairness. Each adaptation option was evaluated
based on the above-mentioned attributes.
ix
The protection option consists of hard and soft technologies: dikes, revetment as a
hard one and beach nourishment, wetland restoration as a soft one. This includes: set
back, full Protection, beach nourishment and managed retreat and accommodation.
Accordingly, the coastline of the governorate was divided into six regions depending
on the adaptation options and the topographic nature of that region.
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Chapter 1
General Introduction
1.1 Introduction
This report documents the approach, methods, and key findings of the coastal zone
team on Coastal Zone Vulnerability and Adaptation Assessment, Aden Governorate,
Republic of Yemen, as a part of the Second National Communication, EPA Project
No. 00044077. This study was funded by GEF.
The document contains several sub-sections that present: 1) The research context,
objectives and approach, 2) Study area characteristics, 3) Potential impact of sea level
rise (SLR), 4) Socio-economic impact of the sea level rise, 5) Adaptation measures
and strategies, and 6) Conclusion and recommendations. Following this, a list of
references and appendixes of supplemental materials. A list of acronyms and symbols
used throughout this report is also provided following the list of Tables.
1.2 Research Context – Assessing Coastal Vulnerability
Human population is attracted, to a greater extent, to coastal zones than to other
regions. Urbanization and rapid growth of coastal cities have therefore been a
dominant population trend over the last decades, leading to the development of
numerous mega cities in all coastal regions around the world. In 1990, it was
estimated that at least 200 million people live in the coastal floodplain (in the area
inundated by a 1 in 1000 year flood), and it is likely that their number increases to 600
million by the year 2100 (Nicholls and Mimura, 1998). Collectively, this would
results in growing demands on coastal resources, as well as increasing people’s
exposure to coastal hazards. Global climate changes are affecting coastal communities
around the world, many of which are already considered vulnerable to ongoing
climatic variability impacts (IPCC, 2007). One of the more certain consequences of
global climate change is accelerated global sea-level rise, which will intensify the
stress on many coastal zones, particularly those where human activities have
diminished natural and socio-economic adaptive capacities. In addition, the impacts
of climate change will include possible increases to sea surface temperatures, greater
variability in the patterns of rainfall and runoff, possible changes to wave climate,
changes to the frequency, intensity and duration of storms, and changes to ocean
chemistry. In light of this, the coast is regarded as one of the most vulnerable areas on
2
the planet and is increasingly the focus for assessments of vulnerability and adaptation
to climate change.
Estimates for the 20th century show that global average sea level rose at a rate of
about 1.7 mm/yr. Satellite observations available since the early 1990s provide more
accurate sea level data with nearly global coverage. This decade-long satellite
altimetry data set shows that since 1993, sea level has been rising at a rate of around 3
mm/yr, significantly higher than the average during the previous half century. Coastal
tide gauge measurements confirm this observation, and indicate that similar rates have
occurred in some earlier decades. Sea level is projected to rise at an even greater rate
in this century.
The two major causes of global sea level rise are thermal expansion of the oceans
(water expands as it warms), and the loss of land-based ice due to increased melting.
Until recently, scientists assumed that thermal expansion dominated contemporary
SLR (Houghton et al., 2001). Recent progress has changed that perception, and it now
appears that mass contributions from glaciers and ice sheets dominate, with the latter
comprising at least half of total SLR over the past decade (Nerem et al., 2006). The
greatest source of uncertainty for predicting future SLR is how large ice sheets will
behave in the future as warming proceeds (Alley et al., 2005; Gregory and
Huybrechts, 2006; IPCC, 2007).
Sea level rise can lead to increased coastal flooding, accelerated erosion, rising water
tables, increased saltwater intrusion, and a suite of ecological changes. These
biophysical changes result in various socio-economic impacts including loss of land,
increasing damage and maintenance costs of coastal infrastructure, changing quantity
and quality of coastal resources, as well as declines in associated economic,
ecological, cultural, and subsistence values (Klein and Nicholls, 1999).
According to the Intergovernmental Panel of Climate Change (IPCC), Fourth
Assessment Report (AR4), global temperature is projected to rise by 1.1 to 6.4°C,
while global mean sea level is projected to rise by 18 to 59 cm, over 1990 levels by
around 2100, based on future scenarios of varying global emission levels (Bindoff et
al., 2007). The most recent evidence suggests that sea-level rise could reach 1m or
more during this century (Rahmstorf, 2007; Dasgupta, et al., 2009).
3
In the context of coastal zones, the goal of vulnerability analysis for sea-level rise
(and other coastal implications of climate change) is to assess the potential impacts on
coastal populations and the related protection systems and coastal resources, including
the ability to adapt to these changes. A range of methods for such analyses has been
developed and these have been extensively applied at the national and sub-national
levels (e.g. IPCC-CZMS, 1992; Klein and Nicholls, 1999). The analysis of the coastal
vulnerability starts with some concepts of the natural system’s potential to be affected
by the different bio-geophysical effects of sea level rise (erosion,
inundation,
flooding, salt-water intrusion, coastal hazards, and rising water tables), and its
natural capacity to cope with these effects (resilience and resistance).
Climate change impacts on Yemen's coastal communities through gradual effects of
accelerated sea-level rise, and more immediate risks of extreme events including
increased storm surge flooding, accelerated coastal erosion, contamination of coastal
aquifers, and various ecological changes. These biophysical changes create risks of
land loss, coastal infrastructure damage, coastal resource changes, and shifts in related
economic, social and cultural values (Klein and Nicholls, 1999). Climate change
impacts are, and will continue to be, unevenly distributed among coastal communities
due to different local exposures and vulnerabilities (Clark et al.,1998; Dolan and
Walker 2006). Yemen considered one of the top five most vulnerable low-income
countries, with more than 50% of their coastal areas at risk, for exposed populations,
and more than 50% of coastal urban areas lie within the potential impact zones
(Dasgupta et al., 2009).
The first assessment of Yemen’s climate vulnerability and adaptation options was
carried out during the year 2000, as a part of Yemen Initial National Communication
(INC), which covered a small part of Yemen’s coastal area, along the Red Sea coast
(Hodiedah city (Al Subbary et al., 2000)). The Second National communication
(SNC) (present study) conducted taking into consideration the good practice and
lessons learnt from the INC and other climate-change related projects. The coastal
zone sector was studied and identified under the National Adaptation Programme of
Action (NAPA), as one of the most vulnerable areas to climate change in Yemen.
While the NAPA process focuses on the national and short-term implications of
climate change on (i) water resources, (ii) agriculture, and (iii) coastal zones, the SNC
4
works at the level of specific geographical hotspots, addresses long-term climate risks
and adaptation on these three sectors. The priority area, targeted by the SNC coastal
zones team, is the coastal zone of Aden Governorate, as a new area of study (Figure
1.1).
Figure 1.1. Map of the study area.
This project describes a general overview of national coastal conditions and trends,
and conducting vulnerability assessment to the impacts of sea-level rise on the coastal
zone of Aden Governorate. Conceivable response strategies and adaptation
technologies discussed.
1.3 Current Approaches and Limitations
Vulnerability assessment includes the susceptibility of the coastal zone to physical
changes resulting from climate change, the anticipated impacts on socio-economic
and ecological systems, and available adaptation options (Harvey et al., 1999).
Coastal zone vulnerability assessment work has been driven largely by IPCC via its
Coastal Zone Management Subgroup (CZMS) (IPCC-CZMS, 1992), the IPCC
Technical Guidelines for Assessing Climate Change Impacts and Adaptations (Carter
et al., 1994), and the United Nations Environment Program (UNEP) Handbook on
Methods for Climate Change Impact Assessment and Adaptation Strategies (UNEP,
5
1998). Sharples (2004) provides a GIS based framework that includes first-pass
indicative mapping at large scale, and more detailed local and site-specific scale
methods. This ‘Smart line’ approach is a cheap and effective method of producing a
geomorphic sensitivity map that may have far reaching applications, especially at a
continental scale. Presently most vulnerability assessments do not yield results
sufficient for widespread, day-to-day application for local coastal zone management
(Klein and Nicholls, 1999).
The study approach to assess climate change impacts was designed by
adopting range of assessment methods, including stakeholders’ involvement, and the
use of expert judgment. The stakeholders were involved in the assessment by
discussions and responses to the questionnaire about the vulnerability and adaptation
to sea level rise in Aden Governorate. Other tools were also used, such as geographic
information systems (GIS) programs. Regarding the modelling, the team explored the
use of Dynamic Interactive Vulnerability Assessment (DIVA) model to give
preliminary idea about the vulnerability of the coastal area to climate change and sea
level rise. DIVA is a tool for integrated assessment of coastal zones produced by the
EU-funded DINAS-Coast consortium (2006). It is specifically designed to explore the
vulnerability of coastal areas to sea-level rise. Its limitation with application at a
national scale does not give particularly insightful perspectives on vulnerability of the
coast to climate change.
1.4 Research Purpose and Objectives
1.4.1 Purpose
Develop a chapter on the vulnerability and adaptation to be submitted as a part of the
SNC of Yemen that;
-
Develop and enhance national capacities, and facilitate the process of
mainstreaming climate change issues into national planning and policy, thus
enabling the country to deal with climate change and consider it not only as
environmental issue but also as an issue of sustainable development.
-
Enable Yemen to prepare and submit its SNC to the UNFCCC and meet its
Convention obligations.
6
1.4.2 Objectives
-
Assess current vulnerability of climate and sectors under the priority area.
-
Assess future climate risk and adaptation measures for the priority area.
-
Develop a policy framework for adaptation for the selected areas.
1.5 Data Used
Data used in this study includes: climatological data of 18 years, monthly air
temperature, wind speed, and sea level pressure, for the period from 1992 tell 2009;
historical tide gauge data for about 60 years, from 1880 tell 1969 with some gaps;
topographical maps of D38-114 and D38-115 covering Aden Governorate with scale
of 1:100,000; socio-economic data, etc.
7
Chapter 2
Study Area Characters
8
The following sections describe the coastal and marine physical environments along
the coast of Aden.
2.1 Coastal Physical Environment
Yemen coast is characterized by a narrow coastal plain between the Gulf of Aden and
the mountain range that parallels the shoreline. This coastal plain interspersed with
volcanic intrusions right to the sea shore extending along the Gulf of Aden. The land
rises steeply inland from the coastal plain to elevations of several thousand meters in
the western part of the country. This range averages 1,070 m in height and influences
the local weather, especially wind. Further east, towards Omani border, the elevations
are not as great. Gulf of Aden is bounded on the north by the Yemeni coastline, and
on the south it is bounded by the Somali Peninsula. The Yemeni coastal line along
Gulf of Aden and Arabian Sea is approximately 1400 km long, extending from Bab el
Mandab at the west to Ras Darbat Ali at the east. The landmasses surrounding the
Gulf of Aden and Arabian Sea are characterized by hot and dry climates with little
vegetation. Strong winds blowing across these areas often carry sand and dust.
2.1.1 Coastal Geomorphology
The Gulf of Aden is a young ocean basin formed by the rifting of Asia (Arabia) from
Africa (Somalia) (Girdler et al., 1980). It has a well-defined continental margin, small
oceanic basin, and an active mid-ocean ridge (Sheba Ridge) in the center,
characterized by a rift valley and fracture zones (Matthews et al., 1967; Bosworth et
al., 2005). The rifting of the Arabian Peninsula was accompanied by violent
movements in the earth’s crust, creating one of the world’s largest volcanic zone
along the western and southern borders of the Arabian Peninsula.
The Gulf of Aden coastline is characterized by sedimentary strata interbreeds of
limestone, sandstone and shale with volcanic intrusions and extrusions. The old
sedimentary strata are primarily marine sediments of Jurassic and Cretaceous periods
(Mesozoic), whereas the coastal plains are often more recent alluvial and marine
sediments (Al-Hubaishi et al., 1984). Most of the coastline exhibits signs of block
faulting, raised beaches, pediments, wadi mouths, headlands, escarpments and dunes.
Volcanic pyroclastics (fragmented material from explosive volcanic processes) from
9
some shore areas are sometimes complex because they exhibit raised beaches with
wave cut platforms and pediments, erosional features common to deserts.
Most geo-morphological (tectonic, erosional and depositional) events, which have
formed the present day coastline, took place in relatively recent, geological time,
primarily during the quaternary period of the Cenozoic Era. The quaternary period
and Pleistocene epoch are coincidental, occurring within the past three million years
(before present). The Pleistocene epoch covers the time of most recent glacial and
interglacial activity.
2.2 Meteorology
The coastal region of Yemen is influenced by two distinct monsoon seasons. The
southwest (SW) monsoon of the Indian Ocean occurs between the months of May and
September, while the northeast (NE) monsoon prevails between October and April.
The months of April, May and October are transitional months as global pressure
patterns re-adjust to the changing incoming solar energy (Al Saafani, 2008). The air
temperatures recorded in this area are among the highest of any coastal regions in the
world (Red Sea and Gulf of Aden pilot, 1987). Mean daily maximum temperatures
exceed 30C at Aden for seven months of the year, while mean daily minimum
temperature only drops bellow 20C in January (Canadian Occidental Petroleum,
1992). Relative humidity is generally higher during the SW monsoon than during the
NE monsoon although the seasonal differences are not large.
In addition, three extreme weather conditions also occur in the Gulf of Aden. These
are locally known as (i) Belat, a strong sand storm, during the winter monsoon in midDecember (it generally persists for one to three days), (ii) Khamasin, hot dry north
wind that blows across the Gulf of Aden during the summer monsoon that occurs for
three to four times a year lasting for 3–4 hours, and (iii) Shamal, also occurring during
the summer monsoon, blows mostly from the north for a few successive days
(Canadian Occidental Petroleum, 1993).
2.2.1 Solar Radiation & Day Length
The annual path of the sun crosses Yemeni coast twice annually, on April 25th and
August 8th, as the sun first moves northward to the summer solstice and again as it
10
retreats to the autumnal equinox. Therefore, the peak energy flux of incoming solar
radiation through a clear sky at local noon has a bimodal peak (Al-Motawakel et al.,
1983). Being close to the equator, the length of the day varies little from twelve hours.
The range in day length from summer solstice (12.87 hours) to the winter solstice
(11.13 hours) is 1.74 hours.
2.2.2 Precipitation
Although the term “monsoon” generally implies heavy seasonal rain, both monsoons
are dry in the study area. The climate of Yemeni coast and nearby waters is dominated
by hot and extremely arid conditions characteristic of North Africa and Arabian
Peninsula (Howe et al., 1968). Precipitation in the region falls infrequently, especially
along the western Gulf of Aden coast and accumulation is light. The data available
from the rain gauge stations in Yemen (Aden and Mukalla) indicates that most of the
precipitation occurs during the winter monsoon. However, at Salalah, along the
southern coast of Oman, most of the rainfall occurs during the summer monsoon
(Canadian Occidental Petroleum, 1993).
2.2.3 Storms
According to National Climate Data Center, the most frequent storms affecting the
area are thunderstorms and blowing sand and dust. The monthly frequencies of such
storms observed offshore range from 0 to 1.7% (Canadian Occidental Petroleum,
1993). Tropical cyclones may influence the region. Occasionally, a tropical cyclone
originating in the north of the Arabian Sea moves into the Gulf of Aden (Murty,
1984). The greatest chance of encountering a cyclone in the area is in November
(Naval Oceanography Command Detachment, 1982).
The eastern Arabian Sea is one of the tropical cyclone genesis regions of the world
(Murty, 1984). These storms generally form in the transitional seasons between
monsoons off southwest coast of India. During the period from 1891 to 1960, a total
number of 165 cyclonic disturbances were formed in the Arabian Sea, half of which
intensified into storms (winds greater than 32 knots). The months of October and
November have recorded the most storms (17 and 21, respectively), while May and
June have had 13 storms each. Forty-eight severe cyclones (wind greater than 56
11
knots) were recorded in the Arabian Sea during the period of 1891 - 1960 (Canadian
Occidental Petroleum, 1993).
The annual probability of a tropical cyclone (maximum sustained winds > 32 knots)
in the western Gulf of Aden is 6.7% and 13.3% in the eastern part (where 50 E
latitude separates west from east) (Canadian Occidental Petroleum, 1993). These
probabilities translate to an average of one tropical cyclone every 15 years in the west,
and one every 7.5 years in the east. Severe cyclone, however, in the Gulf of Aden are
much less frequent. During the periods 1943 - 1967 and 1972 - 1982, a total of only
eight severe storms entered the Gulf of Aden (Pedgley, 1969; Canadian Occidental
Petroleum, 1992). No cyclones reached hurricane intensity (wind speeds of 65 knots)
or greater in the Gulf of Aden during the period 1971 - 1979 (Canadian Occidental
Petroleum, 1993).
2.3 Oceanography
The oceanographic conditions for the Gulf of Aden are also influenced by the
monsoon reversal. The Sea surface temperature (SST) and surface current show
seasonal variability following the air temperature and wind pattern. The most
important phenomena is the seasonal upwelling along the eastern part of Yemeni
coastal line, which enrich the coastal marine ecosystem with the necessary nutrients
for the primary production, making this region one of the most productive of the
world oceans.
2.3.1 Sea surface temperature (SST)
The surface layer showed strong seasonal variations in its characteristics. The SST
was about 24–25ºC during winter (November–February). It increased to reach a
maximum (31ºC) in May. During summer (June–August), the SST decreased along
the northern side due to upwelling. The upwelling temperature along Yemeni coast
reaches a minimum of 17ºC (Pichura and Sobaih, 1986), it started in the eastern side
during June and extended towards the west during July–August. In September, the
SST started to rise again soon after the weakening of summer monsoon winds over
the gulf to ~ 30ºC. Similarly, the mixed layer depth decreased from ~ 80m during
winter to ~ 20m during summer (Al Saafani, 2008).
12
2.3.2 Currents
The recent studies show that the circulation in the Gulf of Aden is not simple as
thought earlier. It is influence by mesoscale eddies that propagate from the Arabian
Sea (Fratantoni et al., 2006, Al Saafani et al., 2007). The net flows at the surface were
westward during October–April and maximum during November to February. This
westward flow would transport water from the Gulf of Aden into the Red Sea. During
summer, the flow is reverse to flow eastward during June to August. The eastward
flow in the western end of the gulf during this season is a continuation of the outward
flow from the Red Sea in the surface layer. This pattern of flow is modified with
mesoscale eddies propagating towards west into the Gulf of Aden (Figure 2.1). These
eddies influence the circulation from the surface to depth of ~ 1000 m (Bower et al.,
2002; Al Saafani, 2008).
Figure 2.1. Schematic diagram showing the pattern of the mesoscale eddies in the
surface circulation in the Gulf of Aden. The acronyms A and C represent anticyclonic and cyclonic eddies respectively.
13
2.3.3 Sea Level
The attempts made to understand the sea level variations in the Gulf of Aden are very
limited (Morcos, 1990). Patzert (1974) presented the sea level changes at Aden and
Perim (Myuun) Island, and concluded that these changes resulted from the reversal of
circulation, which is closely associated with the reversals in the monsoon winds
acting on the sea surface. The sea level at Aden rises between September and May,
and falls during June–July to reach the minimum in August. The seasonal oscillations
in the mean sea level can arise due to astronomical effects, evaporation effect,
precipitation and wadies discharge, atmospheric pressure, and steric sea-level effects.
The effects of purely astronomical conditions (long-period tides) are not significant;
they do not exceed 12 mm at these latitudes (Pattullo et al., 1955). Because rainfall is
very low and no large rivers are discharging into the Gulf of Aden, these two factors
can be ignored. Maximum evaporation over the gulf occurs during winter when the
sea level is highest (Privett, 1959). Since the sea level variations are completely out of
phase with the variations in evaporation, evaporation also does not appear to control
the seasonal oscillations of mean sea level.
The isostatic adjustment of the ocean surface to changing atmospheric pressure
requires that the sea surface rise (fall) by 1 cm for every 1 mbar decrease (increase) in
pressure. Patzert (1974) noted that the atmospheric pressure at mean sea-level is
highest during January and lowest during July at Aden with a range of ~ 10 mbar.
Corrections to the monthly mean sea-level curves for the pressure variations results in
an increase in the range of mean sea level. Thus, the observed variations in mean sea
level do not appear to be due to the effect of atmospheric pressure change.
A variation of the density within a water column, from which the steric sea level is
calculated, depends on the thermohaline variations within the column. It is high when
water is warm and/or less saline and low when water is cold and/or more saline. In the
upper 300 m of the water column near Aden, the steric variations have the same phase
and similar range as the sea level at Aden, though the range of the steric variations is
larger by approximately 8 cm (Patzert, 1974). This variation in density of the upper
300 m of the water column is due to the upwelling of cool, low-salinity water that
occurs in the northern coast of Gulf of Aden during the southeastern monsoon.
14
2.3.4 Astronomical Tides
The tides in the Gulf of Aden are mixed diurnal and semi-diurnal type. There are two
low waters and two high waters per day but these are generally different. The tidal
range exceeds 2m, and the tidal currents are reportedly weak. Along the coast of
Yemen, the flood current apparently sets southeast (Defense Mapping Agency, 1990)
and ebb current flows in the opposite direction.
2.3.5 Upwelling
Understanding the process of upwelling is important since the Gulf of Aden has been
regarded as one of the most productive areas (Kabanova, 1968; Krey and Babenard,
1976; Currie et al., 1973). Piechura and Sobaih (1986) showed that the upwelling
develops first in the far eastern parts of the Yemeni coastal waters in May, and
subsequently, progresses further towards the west. Mostly, the upwelling appears in
separated patches similar to those appear in the coastal waters elsewhere (Boje and
Tomczak, 1978). Awad and Kolli (1992) studied the upwelling process in the Gulf of
Aden by analyzing the hydrographic data collected during 1984–85. They described
the distribution of hydrographic properties and estimated the strength of upwelling.
The most conspicuous feature is the cooling of near surface layer by more than 8ºC.
2.4 Study Area: Governorate of Aden
Governorate of Aden is one of the important governorates in Yemen, where the main
harbor of Yemen, Aden Harbor, is located only 4km from the international navigation
rout. It is one of the largest natural harbors in the world with an area of about 70 km2
of sheltered water surrounded by Shamsan Mountain, Khormaksar, and the shore,
which extends to the hills of Little Aden. The governorate extends between 12º 40 to
12 º 58 N and 44 º 25 to 45 º 7 E with an area of 750 km2.
The geological structure of the governorate of Aden is an integral part of the
composition of Yemen and the Arabian Peninsula. In the time period between the
Miocene and Paleocene, six volcanoes were created along the southern coast of the
Arabian Peninsula, stretching from Perim Island, Gabal Karaz, Ras Umran, Little
Aden Peninsula and Aden (Crater). The last three volcanoes are located in the coastal
area of Aden governorate. Rock formation is of volcanic nature, and the subsequent
15
impact of erosion and weathering, which are still ongoing, has earned a prominent
terrain features.
Aden consists of two parts, The Mountainous region and the Coastal Plateau. The
southern part consists of two peninsulas, Aden and Little Aden, and an intervening
stretch of the mainland. The two peninsulas of Aden are connected by sandy and
muddy encircling Gulf of Al Tawahi. The volcanic rock formation of Ras Umran and
the island of Jabal Aziz is similar in structures and formation to that of Aden and
Little Aden, although erosion great impact had been aggravated
from the marine
side.
Aden Governorate has 21 islands and rocky heads mainly found around Little Aden
and Ras Umran and Gulf of Al Tawahi, in addition to Perim Island in Bab el Mandab,
which follow the Aden governorate administrative. Offshore islands around Aden is a
rocky islands supporting a scattered coral reefs and are mostly fishing areas in
addition to many other activities. Following are the discretions of the two peninsulas:
2.4.1 Aden Peninsula
Aden Peninsula is an oval-shaped rock formations centered with a six km in diameter
crater. These formations extended westerly to form Shamsan Mountain with a range
as high as 531 m above sea level. At Ras Tarchin the rock formation split towards the
east and south to form Al Mandar Mount at the east and Mount Aidaroos at south, and
terminated in the south east at the head of Ras Ma’asheeq.
At the southeast side of the crater, a series of branched sub-mountains Alta’akor, Al
Mansuri and Al Akdar mount formed. Another extension of the rocky mountain
extends toward the northwest and ends at Hadeed Mount.
The rigid configurations slope sharply into the sea to form a number of heads and
bays. The most important of which are Ras Ma’asheeq, Ras Antouk, Ras Tarsheen,
Ras Marbat, Serah Bay, Hakat Bay, Fishermen Bay, Gold Moor Bay, etc., are formed
at the meeting points of the mounts and the water.
16
2.4.2 Little Aden Peninsula
Little Aden peninsula is a range of hills interspersed with sandy depressions most
vulnerable to erosion. Most forms of terrain is Almzalghem Mount, Mount Ihssan and
a number of mountain peaks known as Albrouj, where the highest high of 350 m
above sea level.
Little Aden Peninsula, is surrounded by a number of rocky headlands and bays. The
most prominent head lands are Ras Khesa, Ras Abu Kyamah, Ras Mjelb Hadi, Ras
Ulagah, Ras Foqm. A number of bays with sandy beaches stuck between these
headlands such as Khesa Bay, Bay of Darbah, and Bay of Bandar Sheikh.
2.4.3 The Coastal Plateau
The Coastal Plateau is located in the northern part of Aden, which starts by linking the
two peninsulas to the mainland, then ascends gradually towards the north. This
Plateau is flat, mostly covered with sand dunes and includes two wadies (Wadi Al
Kabeer and Wadi Al Sageer). The two wadies are considered as extensions of Tuban
Wadi, which is located in Lahj Governorate, and include Tuban Delta in between.
These two wadies are terminated at Al Tawahi Bay.
Aden Governorate’s coastal area extends from Qa'awa in the west to Al Alam in the
east. As mentioned above, Aden as a part of Gulf of Aden is influenced by the
monsoonal variations. Using monthly values for air temperature for the period from
March 1992 to December 2009, monthly climatology of air temperature for Aden was
created (Figure 2.2). The annual mean air temperature is about 30 ºC. Whereas the
highest monthly mean is 33.8 ºC during June, the lowest monthly mean is 26.5 ºC,
which occurs during January. The relative humidity is between 66 – 75%, and the
amount of precipitation is only 50 mm per year, since Aden is a part of the arid
region. There are periodic rainy seasons with cycles of 12-15 yeas (EPAG, 2009).
Mean annual temperature has increased by 1.8°C since 1960, a rate of around 0.39°C
per decade. The rate of increase is most rapid in summer (June, July, August), with
increases at an average rate of 0.56°C per decade and slower in winter (December,
January, February) at a rate 0.21°C per decade. The rate of warming in Yemen is
more rapid than the global average. There is insufficient daily temperature data
available to determine trends in the frequency of hot and cold days and nights. Mean
17
rainfall over Yemen has decreased since 1960, at a rate of 1.2mm per month (~9%)
per decade. These decreases generally affect the drier seasons. There is insufficient
daily precipitation data available to determine trends in heavy rainfall events
(McSweeney et al., 2007).
34.00
Temperature (C)
32.00
30.00
28.00
26.00
24.00
22.00
20.00
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Months
Figure 2.2. Climatology of Air temperature in Aden, created from monthly values
from 1992-2009.
The topographic structure of the coastal plain of Aden comprises of three classes as
described by MEP (1995). The rocky sub-littoral coasts, this includes Crater and
Buraiqah, medium energy sandy coastal plains with fine sands, this type mainly
located from Khormaksar east to Shuqra, and the same from Ras Umran to Qa’awa.
The third type is also fine substrates of low energy of mud/fine sands, this type is
located along the sheltered Al Tawahi Bay between the headlands of Little Aden and
Crater, as well as the sheltered sandy bay to the west of Ras Foqm. The second and
third classes are more vulnerable to sea level rise and climate change as the coastal
slope is less the 5º.
2.5 Population and Administrative Divisions
According to the 2004 Census, the population of Aden Governorate is 598,419, of
which 53.2% is male. This population composes about 3% of total the Yemen
population with a growth rate of 3.53%. The average number of families of Aden
Governorate is 90,667, and number of dwellings is 97,408 households. From the
population and number of families and dwellings, it can be found that the average
18
numbers of family members is 6.5 persons, and number of residents per household is
6.1 persons.
Aden Governorate population is distributed along its eight administrative divisions
(districts), which are Buraiqah (or Little Aden), Al Tawahi, Al Shiekh Othman, Al
Mua’alla, Al Mansoorah, Khormaksar, Dar Sa’ad and Seerah. Aden peninsula
contains most of the city's population and is divided into a number of districts. Little
Aden peninsula contains the city's main industrial district and is the site of a large oil
refinery. However, Aden with its harbor together with Al Shiekh Othman, hold most
of the commercial and administrative activities.
2.6 Coastal and Marine Environment
Gulf of Aden’s marine and coastal ecology has received little attention, particularly
that of Aden city. However, the few studies and surveys conducted by the Marine
Science Research and Resource Center (MSRRC) were focused on the fisheries
aspects, and covered the near and offshore areas of the Gulf of Aden (20-500m)
(MEP, 1995). CEMP (1985) had conducted a survey of the main habitats and species
in the Yemen southern coastal region. The study highlighted the sites of special
interest. In Aden Governorate the following locations were recommended to be of
ecological importance:
Sites
Ras Umran
Importance
Coral reef, seagrass beds, turtle nesting
Ras Abu Quijara
Rocky shores, submarine hard bottom
communities, coral reef
Shallow bay, rich fishing ground
Mud flats, bird & high productivity
Mud flats, bird & high productivity
Exposed sandy beach
Bandar Foqm
Farisi Lagoon
Aden Inner Harbour
Khormaksar Beach
Reference
Ehrenfield1981;
CEMP,1985
MEP,1996
CEMP,1985
CEMP,1985
CEMP,1985
CEMP,1985
Preliminary work has been under taken on coastal zone between Bab el Mandab and
Ras Darbat Ali, including comprehensive surveys of ecosystems (MEP, 1995). This
survey covered eleven locations along 150 km of Aden coastal area and described
their topographic and ecological characters.
19
The geomorphologic structure and composition of Aden coastal area have contributed
directly to the type and conditions of its environment, and helped to form a number of
distinguished marine and coastal habitats. The formation of rock heads and
mountains, which extend into the sea, have led to the creation of a number of bays and
hard substratum which form the suitable conditions for coral growth in the vicinity of
Aden (Crater) and little Aden Peninsulas. Meanwhile, the processes of erosion and
alluvial sediments (Mud) prevailed during a long period of time have contributed to
the formation of sand plains, marshes and mud flats. These created favorable
conditions for growth and reproduction of many species of plants and animals (marine
and terrestrial). Consequently, the following marine and coastal environments form
the main features of Aden Governorate coastal area: 1. Coral reefs.
2. Sea grass beds.
3. Turtle nesting sandy beaches.
4. Wet lands.
5. Rocky shores.
6. Birds (local and Migratory).
7. Mud flats.
8. Fresh & salt water vegetations.
2.6.1 Rock shores
Rocky shores of Aden are mainly occurring in Crater, Little Aden and Umran, and
surrounding islands in the form of steeply sloping volcanic mountainous intrusions
and extrusions, and wave cut platforms.
The coral and coral fauna forms a veneer over steeply sloping volcanic rocks and
boulders down to 8 m depth, where a gently sloping sandy bottom prevents further
colonization. Many of the marine and climatic features have helped the growth and
prosperity of the coral reefs in some areas, including water clarity and the absence of
20
wadies, as well as the warm temperatures and water currents. Corals are found as
patchy and fringing reef.
Live coral cover is high on average (30 - 50 %), although it reaches 100 % in some
places. Massive growth forms of Porites colonies dominate, with at least 20 other
genera, including large colonies of Lobophyllia, Galaxea, the solitary coral Fungia
spp. and Turbinaria spp. in deeper water. Rosen (1971) reports a total of 32 genera for
the Aden area.
Reefs in Aden support good coral communities of reef fishes, such as parrot fishes,
butterfly fishes and surgeon fishes. Rock lobster and other marine invertebrates and
algae are found in extensively numbers reflecting the high productivity of Aden reef
community. Artisanal fishers depend greatly on fish and lobster resource of this area.
Studies of Kemp and Benzoni (2000) had confirmed the presence of highly dense and
divers coral communities in Aden waters around the sub-tidal rocky substrate. The
presence of corals around Seerah is sparse and consisting of small colonies of
branching species (Stylophora sp, Pistilata sp, and Acropora sp).
In little Aden, corals are scattered parallel to the rocky shores with 50 to 150m in
length, and down to 6 meters. Corals of this region are solid and massive forms and
mainly massive Porites sp, Gonipora sp, Siderastrea sp, Platygera sp, Galaxea sp,
and few of the branching coral Acropora sp, Stylophora sp and Pistilata sp. Most
coral reefs in these locations is poorly evaluated and are under pressure due to a high
concentration of fishing activates, anchoring, messing nets and pollution.
2.6.2 Sandy Shores
A medium energy sandy shores, mainly located on the long stretched, exposed shores
(Khormaksar) and between headlands, forming coarse to medium sandy bays (little
Aden). Khormaksar intertidal and supra-littoral fringe harbor many mollusks and
crabs, and support important bird’s populations.
The sandy shores bounded by igneous mountains in Crater and Little Aden such as the
Gold Moor, Elephant Bay, Wreck Bay, Sapper Bay, Round Island Bay, Bandar Daras,
Hokat Bay, refinery recreational bay, Ghadeer Bay, and Bandar Foqm, are formed
21
from medium to coarse sandy beaches and some are mixed with calcareous shells
fragments. All the shores are used as recreational beaches, and are under threat from
intensive development along its supra-littoral fringe. Foqm village’s sandy beach
forms the landing site of the biggest artisanal fisheries in Aden. The sandy beach west
of Ras Umran is formed from flat plain and desert dunes inland that gently descent to
coarse sand with pebble and many fragmented shells supra-littoral shore.
Seagrass beds located in Umran Bay and Tawahi bay in scattered locations. There are
two types of seagrass beds in the inner harbor Halodule uninervis, Halophila ovalis,
(MEP 1996, Golder and Associates 1998). Seagrass beds is one of the important
habitats of highly productive ecosystems forming a feeding areas for many of the
benthic, fish, turtles and nursery areas for many of the neighborhoods most important
economic fishes and crustaceans. Halophila ovalis, Cymodocea sp. and Haloddule
uninervis are also reported from Umran Bay, and Khor Bir Ahmed.
The southern coastal of Yemen is ranked as one of the most important regions in the
world for turtle nesting and breeding of green turtles. Reports indicated that the area
of Jabal Aziz should be given priority in the maintenance of turtles (UNEP, 1985).
Sandy beaches of Aden regions are important for nesting of two endangered species
(green turtles Chelonia mydas and Hawksbill Turtles Eretomchelys imbricata), which
today may be less abundant than it was in the past, due to increased human activity in
the coastal zone area.
2.6.3 Muddy shores
Muddy shores in Aden present in enclosed inlets of Aden inner harbour, where wave
action and other movements are of low energy. This enables the suspended mud to
settle down to form mud flats or wetlands. Aden wetlands consists of Aden inner
harbour east of the cause way (Aden Lagoons), salt pans and extend to little Aden
including Aden marsh, which form a large area of marsh and Dom palm, created by a
long established sewage outflow at Al Hiswah. They also found to the west of Ras
Foqm and the back side area of Abyan beach. Al Gadeer semi-enclosed beach is
mainly formed from silt materials and retain some of the muddy environments.
The great productivity of the wetland at Al Hiswah sustains a unique diversity of flora
and fauna. A fairly numbers of plant species recorded are listed in table 2.1.
22
The wetland vegetation supports a number of wildlife species, especially migratory
and domestic birds, which considered a safe haven for many of them and for a large
number of wild animals such as rabbits, foxes, reptiles, scorpions and bats.
Despite the high salinity of Aden saltpans, a number of plants species appear to
tolerate and adapt the high concentrations of the dried salts. These plants include
Tamarix spp, Prosopis juliflora, Sueada monoica, Sueada fruticosa, Typha elephant
aiodes, Cyprus laevigatus, Sporbulus spicatus, and Odyssia mucronata.
Aden lagoons are located in the innermost recess of Aden inner harbor were resulted
from the construction of the causeway across the Bay of Aden in shallow waters. One
main gate and secondary pipes situated under the road to feed three main lagoon
bonds. Behind the three main ponds, the salt pans are existed. Water quality is
unknown but high salinities might be expected, resulting from shallow waters and
intense evaporation. Bottoms are sandy near the sea shore but turn gradually to mud
in all parts of the lagoons.
These lagoons are important for their environmental and bio-diversity nature, and role
as feeding ground of many species of birds in addition to the presence of many plants
and marine organisms. They own an aesthetic dimension as a coastal park to the
Tourism of Aden and economic assets. They provide a natural protection for the builtup areas and economic activities of the nearby areas from tidal waves. It is also home
to many sea grass species such as Halophila stipulacea , Cymodocea searulata , and
Kalodule uninervis.
The importance of seagrass beds appear, in the settling of the seabed soil erosion and
deposition and accumulation of organic materials and inorganic. Seagrass beds form a
habitat for a wide range of marine flora and fauna and a direct source of food for the
animals that live on it, such as crustaceans, sea urchins, herbivorous fish, mollusks,
and birds. On the boarder of the lagoons some coastal plants are nourished, such as
Sporobulus spicatus, Odyssia mucronata, Sueada fruticosa, and Sueada monoica.
The Lagoons supports many types of marine fauna such as fish (latycephalide and
Mugilidae), crustaceans, (Penaeidae and crabs) and mollusks (Stromdidae). There
high productivity is considered as important feeding, nursery and proliferation place
23
Table 2.1. Plant species listed in Al Hiswah wetland.
Forest Plants
Cultivated Plants
Grazing plants
Echoinchloa colona
Inga deluce
Echiocnloa colona ((L)) Lank
Sporopulus spicatus
Conocarpus lancifolius
Cynadon dactylon
Panicum antiditole
Catharanthus rosus
Eluropis lagopoides
Lasiurus hirsutus
Nerium oleander
Sporobulus spicatus
Cynadon dacylon
Casuarina equisitifolai
Cyperus laevigatus
Aeluropis lagopoides
Prosopis cinerria
Lasiurus hirsutus
Chloris barbata
Prosopis juliflora
Odyssia mucronata
Odyssa mucronata
Acaica nilotica
Chloris barbata
Cyperus laevigatus
Prosopis chiliensis
Panicum antiditole
Cyperus conglomartus
Azidrachta indica
Prosopis juliflora
Pheonix dactylifera
Prosopis chiliensis
Pennisitum spp
Sueada fruticosa
Syzigium cuminii
Sueada monica
Hyphaene thebica
Halopeplis perfoliata
Cormulaca amblycanthus
Calotropis procera
Leptadeia puyrothecnica
Euphorbia granulata
Hyphaene thebaica
Pheonix dacytlifera
Typha elephataiodes
Tamarix aphylla
Ziziphus spina – christi
Acacia tortilis
Balanites eagyptiaca
Acacia ernheber giana
Auphorpia granuata
Halopyrum mucronatum
Sevada schimperi
24
for a large number of fish species and marine invertebrates. They also provide a
suitable environment for a large numbers of migratory and endemic water birds and
other water fowl.
The wetlands of Aden (saltpans, freshwater wetland and lagoons) form an important
staging and wintering areas for a wide variety of migratory waterfowl, notably
shorebirds, gulls (including Larus leucophthalmus) and terns, with at least six species
occurring in numbers exceeding 1 % of the regional population (Table 2.2).
Accordingly, Aden wetland has identified as an important bird area by Bird Life
International. It is considered amongst the most important wetlands in Yemen and
Arabia.
Table 2.2. List of common bird’s species associated with Aden wetlands.
Name
Cattle Egret, Bubulcus ibis
Imperial Eagle, Aquila heliaca
Western Reef Heron, Egretta gularis
Moorhen,
Little Egret, Egretta garzetta
Black-winged stilt, Himantopus himantopus
Black Egret
Pied avocet, Recurvirostra avosetta
Grey Heron, Ardea cinerea
Pacific Golden Plover,
Black-headed Heron, Ardea melanocephala
Little Stint, Calidris minuta
Sacred Ibis, Threskiornis aethiopicus
Temminck's Stint, Calidris temminckii
Glossy Ibis, Plegadis falcinellus
Ruff, Philomachus pugnax
African Spoonbill, Platalea alba
Black-tailed Godwit, Limosa limosa
Greater Flamingo, Phoenicopterus roseus
Curlew sandpiper, Calidris ferruginea
Lesser Flamingo, Phoenicopterus minor
Spotted redshank, Tringa erythropus
Pintail, Anas sp.
Common greenshank, Tringa nebularia
Garganey, Anas querquedula
Common Sandpiper, Actitis hypoleucos
Northern shoveler, Anas clypeata
Gull-billed Tern, Sterna nilotica
Black Kite, Milvus migrans
Chestnut-bellied Sandgrouse, Pterocles
exustus
Greater Spotted Eagle, Aquila clanga
Alaemon Alaudipes
Galerida Cristata
Streptopelia Rosegrisea
Pycononotus Xanthopygos
Streptopelia Semitorquata
Anthreptes Metallicus
Streptopelia Seneglensis
Corvus Splendens
Oena capensis
Passer Domesticus
Centropus Superciliosus
Ploceus Galbula
Upupa Epops
long-legged buzzar, Buteo rufinus
Dark chanting goshawk, Melierax
metabatus
Esprey, Pundion haliaetus
Sriffon vulture, Gyps fulvus
Egyptian Vulture Neophron percnopterus
Lanner falcon, Falco biarmicus
Sparrow gawk, Accipiter nisus
Osprey, Pandion haliaetus
White-eyed Gull, Larus leucophthalmus
25
Artisanal fisheries is the main traditional livelihood in Aden and the traditional
fishermen is the main fish producing sectors, which covers the needs of Aden and
surrounding governorates. The main fishing and landing villages are Qa’awa, Ras
Umran, Foqm, Khesa, Seerah (Table 2.3).
Table 2.3. Fishers and fishing boats numbers (MFW, 1998).
location
No of
Fishers
Qa’awa
Ras
Umran
Foqom
Keisah
Seerah
255
Fishers
family
no.
1000
No & Type of fishing boats
777
4000
105
140
4
249
4
245
636
600
400
5000
8000
2000
58
60
5
85
200
275
1
-
144
260
280
1
144
260
280
Wooden
28
Fiberglass
50
sambouk
1
total
79
No & Type of
engines
Internal
External
1
78
Aden is characterized by being one of the major fishing areas along the southern coast
of Yemen. Coastal waters rich with fish as well as crustaceans and mollusks of
commercial value. Fishing locations are concentrated in coastal areas near deep and
varies from 5 to 30 meters and using deferent catching gears. Total annual production
of fish and marine life in the province has increased from 4,135 tons in 1990 to
24.545 tons in 1999, with absolute growth rate of 593%.
Recent development activities have accelerated the nature of the threats to
biodiversity and natural habitats. Table (2.4) lists the coastal area in need of special
management for their importance, economically and environmentally.
2.7 Review of SLR in Aden
As mentioned above, the IPCC fourth assessment report suggested rise in sea level
globally by 18-59cm by the end of this century. Regionally, Unnikrishnan and
Shankar (2007), using stations from the northern Indian Ocean, showed that the sea
level at Aden rises by about 2 mm/yr, which is similar to that of the global estimate.
Woodworth et al. (2009) showed that the sea level rise at Aden is similar to that of
26
Table 2.4. Coastal areas recommended for special management in Aden due to their
biological, environmental or recreational importance.
Location
Habitat
Species
Fishing
1
Ras
Qa’awa
Ras
Umran Is.
AL
Guhub Is.
Gabal al
GaziraRas Abu
Qiama
Habban
Is.
Birds,
Turtles
feeding
Turtle
nesting
Birds
+
2
Seagrass, Coral
reef, Sandy
beach
Sea grass, Coral
reef
Coral reef
3
4
5
6
Khor Bir
Ahmed
7
Al Hiswa
8
Inner
Aden Port
Caltex
Swamp
9
Recreation
Sci*
Impact
Source
+
+
4
+
Sandy
beach
+
Fishing
1, 2, 4
+
Snorkkeling
+
Fishing
4
Fishing
Swimming
Snorkeling
+
Oil pollution
Land filling
3, 4
+
Urban
Fishing
4
+
Urban
Fishing
2, 4
Urban (free
zone)
Urban (free
zone)
Grazing
4
Coral reef,
Rocky shores
Coral
reef
Fishes
+
Seagrass, Coral
reef
Birds
+
Seagrass, Coral
reef, Silt, Mud
flat
Sand beach,
Palm trees
Seagrass, Coral
reef, Mud flats
Swamp(sewage)
Birds
+
Birds
+
Birds
+
Sandy
beach
Fishing
Fishing
+
+
Birds
10
Aden
Lagoons
Wetlands
Birds
+
Fishing
+
11
Fishermen Bay
Turtle nesting
Birds
+
+
12
Khormaksar
Beach
Sand beach
Birds
+
Swimming,
Sandy
beach
Fishing
Swimming
Fishing
Sandy
beach
+
2) CEMP1985
27
3,4
Urban
,Fishing,
Land filling
,Oil
pollution.
Hunting of
turtles
4
Urban
filling Oil
pollution,
Sewage
2, 3, 4
* Scientific importance
Sources: 1) Ehrenfield 1981
4) Current Study
2, 3, 4
3) MEP 1995,MEP1996
4
other places in the globe. These studies confirm that sea level is rising at Aden and
will continue in future. Most of Aden sandy coasts are lowlands (like Khormaksar),
and hence, the Governorate of Aden is considered as a sensitive site, and will be
affected by global climate change and accelerated sea level rise. This in turn would
lead to the destruction of residential and industrial areas, commercial and natural
resources, coastal erosion, destruction of marine habitats, natural reserves, and the
bulldozing of the soil and the elimination of the coastal wetlands in low-lying areas
(PERSGA, 2001).
2.8 Selection of Scenario
Two possible future sea-level rise scenarios for Governorate of Aden coastal region
are adopted. Values are in meters above main sea level (MSL), which is 1.4 m above
CD (Chart Datum) for Aden. Scenarios are based on (i) observed rates for Aden mean
sea-level rise, 3.3 mm/yr (Woodworth et al., 2009), and (ii) extreme sea-level rise rate
of 5.9 mm/yr (derived from IPCC (2007)) at highest high tide (HHT) is included for
an extreme scenario. Scenarios of 0.33, and 0.6m SLR over this century were
assumed.
28
Chapter 3
Potential Impacts of Sea Level Rise
29
The rise in sea level would affect the wetlands and lowlands, results in the
acceleration of the coastal erosion, exacerbate coastal flooding, threaten coastal
structure, raise the water table and increase the salinity of bays and aquifers. The main
limitation, as explained earlier, for making accurate assessment of the vulnerability of
the coastal zone to sea-level rise has been the lack of data on the topography of the
coastal area to the desired accuracy (i.e. to enable the delineation of the maximum
water level). As much as possible, data was derived from available toposheets of 40 m
contour intervals, from which the maximum water level interpolateed.
3.1 Erosion
An acceleration in sea-level rise will widely exacerbate beach erosion around the
globe (Brown and McLachlan, 2002), although the local response will depend on the
total sediment budget (Stive et al., 2002; Cowell et al., 2003a,b). The impacts of sea
level rise, and increased coastal erosion and flooding hazards, will affect tourism and
recreation activities in coastal communities, by effecting coastal transportation
infrastructure and marina maintenance, dredging activities, boating safety, vacation
housing and resort infrastructure (Craig-Smith et al., 2006; Walker et al., 2007). Most
sites currently experiencing erosion can be expected to show continuing erosion in the
future, and rates are likely to increase. Therefore, planning and development should
not be based simply on historical rates of erosion, but should consider an appropriate
additional setback to account for more rapid erosion over the life of a structure or
other development.
The loss of land attributable to sea level rise will occur from erosion of sandy shores
and erosion prone cliffs. Shoreline recession results from the offshore transport of
sand. On steep rock coasts, sea level rise may have an insignificant impact. The
recession comes from the adjustment of the active profile to a new elevated water
level. The cross-shore profile adjusts itself by redistribution of sediment, such that the
active zone rises with the rise in sea level while maintaining the same cross-sectional
profile. This results in a loss of beach area. The apparent loss of sediment is
proportional to the width of the active zone.
The best known and most widely applied model to estimate erosion has been
developed by Bruun (1962), for application on straight sandy shores (see also Dean,
30
1990; Healy, 1991; 1996; Mimura and Nobuoka, 1995). In other erosion prone coastal
environments alternative erosion models have to be used, which, however, are often
based on the Bruun rule.
An important limitation for the quality of data available for this assessment has been
the data on coastal topography to the required scale and accuracy. Available
topographic data for the pilot area is usually in the form of 1:10,000 scale maps.
Unfortunately, these could not be obtained for the entire study area. Furthermore,
maps obtained from the (General Authority for Lands and Surveying and Urban
Planning) with 1:100,000 scale toposheets, of 1987, has been taken as base maps. In
fact, such maps is not accurate enough for the intended purposes, showing contour
intervals at 40 m levels only. The location of the HHT contour line has been found by
interpolation between the 0 and the 40 m contour. To get the actual elevations from
the shoreline, several ground truthing topographic profiles were surveyed along
Khormaksar coast. Elevations relative to the current sea level were measured, and
then the data were corrected to the MSL. The new elevations were incorporated to the
base map.
The analysis by Bruun assumes that with a rise in sea level, the equilibrium profile of
the beach and shallow offshore moves upward and landward. Following a number of
assumptions, Bruun derived the basic relationship for the extent of shoreline recession
R, due to an increase in sea level, S:
R = (L/B + h) S
Where, L is the cross shore distance to the water depth h, taken by Bruun as the depth
to which near shore sediments exist (depth of closure), and B is the height of the dune.
The analysis is two-dimensional and assumes: a) the upper beach is eroded due to the
landward translation of the profile; b) the material eroded from the upper beach is
transported immediately into the offshore and deposited, such that the volume eroded
is equal to the volume deposited; and c) the rise in the near shore bottom as a result of
deposition is equal to the rise in sea level, thus maintaining a constant water depth in
the offshore (SCOR, 1991).
For the present study, the following values pertain: S = 0.33 m, 0.6 m; B was
estimated at 1.0 m a long Khormaksar Beach and 1.5 along Foqm Bay; h is the depth
31
of closure in meters, which is calculated by the following equation derived by Dean
(2002):
 H2 
h  1.75H s  57.9 s2 
 gTs 
Where, Hs is the annual exceeded wave height in a 12-hour period, and Ts is the
associated wave period. As there are no records of wave characteristics for the study
area, the total wave height was estimated from sea and swell waves using the
following:
Total Wave Height = [(Wind Wave Height)2 + (Swell Wave Height)2] 1/2
Wind wave height estimated from the wind speed following Quayle (1980), as 0.5 m.
Whereas, the swell wave height was used following Red Sea and Gulf of Aden pilot
(1987) as 2 m.
Hs = (0.52 + 22) 1/2
After estimating the depth of closure (h), the cross shore distance (L) was estimated
following Dean (1990):
L = (h/A)3/2
Where, A is the scale parameter determined from the median sediment size (D50). For
that, sediment samples were collected from Khormaksar beach and the (D50) was
estimated after the grain size analysis of the samples.
Using the above parameters, the Bruun rule gives a depth of closure of 3.2 m.
Consequently, the recession of the shoreline was estimated at about 23 m and 41 m
along the eastern part of the study area (Khormaksar till Al Alam), for rise in sea level
of 0.33 m and 0.6 m, respectively, and about 18 m and 33 m, respectively, along the
western shoreline (Foqm Bay). This was translated to a potential land loss along the
entire shoreline of the pilot area (length 23 km) about 48 and 86 ha, respectively.
32
3.2 Inundation
Sea level rise will lead to inundation of coasts worldwide with some small Island
States, possibly facing complete inundation. Low-lying coastal areas such as deltas,
coastal wetlands, and coral atolls may face inundation as a result of sea level rise.
Land loss resulting from inundation is simply a function of slope, the lower the slope,
the greater the land loss. In addition, the survival of coastal wetlands is dependent
upon sediment availability and local biomass production, as well as the potential for
these ecosystems to migrate inland. Healthy, unobstructed wetlands in settings with
continuing sedimentation are expected to be able to cope with projected global sea
level rise, although ecosystem characteristics may change. However, with the
continuing urbanization of the coastal areas, people build structures just above the
marshes. The increase in sea level will put a squeeze on these wetlands between built
structures and the coast, which will result in the reduction of production of organic
materials, which is essential for nearby ecosystem.
As described earlier, the topographic structure of the coastal plain of Aden comprises
of three classes: the rocky sub-littoral coasts, medium energy sandy coastal plains
with fine sands, and fine substrates of low energy of mud/fine sands. The second and
third classes are more vulnerable to inundation due to sea level rise and climate
change as the coastal slope is less the 5º.
As explained in chapter 2, two plausible future sea level rise scenarios for the
Governorate of Aden coastal region are provided in Table 3.1. Scenarios are based on
observed rates for: Aden mean sea level rise rate of 3.3 mm/yr, and extreme sea-level
rise rate of 5.9 mm/yr, at HHT is included for an extreme scenario. Scenario for water
levels was estimated in meters above MSL, as follows.
SWL = {(rate/1000) x (year - 2008)} + HHT – MSL
Scenarios of 0.33, and 0.6 m SLR over this century were assumed. Sea level rise for
Aden Governorate for 2020, 2050, 2080 and 2100 based on these scenarios are shown
in Table 3.1. Values are shown as metres above MSL, which is 1.4 m above CD for
Aden, from the year 2008. The total land area that would be inundated under the
various climate change scenarios is substantial. With the proposed sea level rise of 33
cm, the percentage of the inundated area is 43 Km2, which represents 5.7% of the total
33
area of Aden Governorate (about 750 km2). The inundated area would increase to
about 45 km2 (6%) for SLR of 60 cm. Inundation will unevenly affect Aden
Governorate coastal area. Khormaksar, Al Tawahi Bay, the coastal beach between
Khormaksar and Al Alam (Abyan Coastal Beach), Aden lagoons and wetlands are the
most affected regions. About 3.90 km2 will be inundated in the dens populated area of
Khormaksar, Al Mansoora, and Al Mua’alla Districts for SLR of 33 cm, while 4.35
km2 would be inundated for SLR of 60 cm. The total socio-economic loose is
described in chapter 4.
Table 3.1: Sea level rise scenarios for Aden Governorate for 2020, 2050, 2080 and 2100
based on observed rate of sea level rise (3.3 mm/yr), and the global extreme scenario 5.9
mm/yr. Water level scenarios are expressed as meters above a local MSL (1.4 m above CD)
occurring at HHT to provide an upper limit for each scenario.
Scenario
observed rates of SLR (3.3 mm/yr) at HHT
Global extreme (5.9 mm/yr) at HHT
2008
1.03
2020
1.07
1.10
2050
1.17
1.28
2080
1.27
1.45
2100
1.33
1.57
3.3 Saltwater Intrusion
As sea level rises, fresh groundwater and surface water could be displaced by saline
water, which could have substantial adverse impacts on drinking-water supply and
agriculture. It is important to note that saltwater intrusion is already occurring in many
coastal regions, owing to overexploitation of surface water and groundwater ( Han et
al., 1995). With growing populations in coastal regions, saltwater intrusion due to this
problem is expected to occur more widely, and may enhance the rate of saltwater
infiltration. Therefore, it is likely that sea-level rise will exacerbate an already adverse
situation.
Assessing the extent of saltwater intrusion in groundwater is difficult because it
depends on many factors that are locally variable and often poorly understood. These
factors include subsoil characteristics such as porosity and conductivity of the aquifer,
hydraulic resistance of the aquitard, and hydraulic variables such as groundwater flow
and recharge. Also, the geohydrology is important because this determines whether a
34
freshwater aquifer is confined, semi-confined, or unconfined; sea level rise will not
result in saltwater intrusion in confined aquifers.
Saltwater intrusion in groundwater can be assessed using analytical methods or
mathematical modelling. One commonality of the analytical methods is that they are
all based on the Badon Ghijben-Herzberg principle, which describes the equilibrium
of two stationary immiscible fluids of different density (Badon Ghijben, 1889;
Herzberg, 1901). Thus, these methods assume that a sharp interface exists between
fresh and saline groundwater. The Ghyben-Herzberg principle provides an initial
estimate of the inland extent of saltwater intrusion in a simple unconfined aquifer of
infinite depth. This theory assumes two fluids separated by a sharp interface and
ignores many of the complexities found in real aquifers. The principle assumes that an
equilibrium condition exists between the saltwater offshore and a freshwater flowing
from upland area down toward the ocean. As shown in Figure 3.1, since the saltwater
is 1.025 times denser than the freshwater, the saltwater/freshwater interface lies a
distance below mean sea level (H) for a given height of the freshwater above mean
sea level (h). The product of the density of saltwater times its height is balanced by
the density of freshwater times its height.
In equation form:
1.025 x H = 1.0 x (h + H)
At any point in time, for every foot that the freshwater table lies above mean sea level,
the depth to the saltwater is 12 m (40 ft) below mean sea level. Therefore each
increment of sea level rise reduces the freshwater capacity of the aquifer by 40 times
(Gornitz, 1991).
Currently, Aden Governorate water supply depends largely on underground sources
(Tuban & Bana Delta Basins, which are located in other governorates (Lahj &
Abyan), and extracted from Bir Naser, Bir Ahmed, Rowa and Tuban well field
(GAWSP-II STAGE, 2001). Bir Nasser Well field is situated 25 km north of Aden
Governorate at the middle of Delta Tuban (Lahj Governorate). It is the main source of
water supply for Aden as it covers 40% of the requirements (Haidera, 2007).
35
Figure 3.1. Saltwater intrusion in a coastal aquifer.
Bir Ahmed aquifer is the only well field located in Aden Governorate. It is mainly
alluvium sand gravel and clay, and is a continuity of Delta Tuban (Figure 3.2). It is
the second main water source for Aden Governorate, especially for Little Aden and its
suburbs. Specific conductance (SC) readings for Bir Ahmed increase from 1800 to
2400 µS/cm, in the northwest to a range between 3000 and 5000 in the area to the
east. The interface between the fresh water and saltwater is at 500 m depth, since the
water level depth is about 10 - 12 m above sea level. The increase of sea level will
result in land propagation of this boundary.
It was stated in the previous studies (Sogreah, 1981) that by maintaining the
extraction levels at 5 Mm3/yr from Bir Ahmed, 12 Mm3/yr from Bir Nasser and 10
Mm3/yr from Tuban, it would be possible to protect these well field from
deterioration, high salt content and fast water level drop due to over extraction.
Number of wells in each well field, production and static water level up to the year
2001 are summarized in Table 3.3.
36
Figure 3.2. Base map of Delta Tuba and Delta Abyan (Source: Komex 2002).
37
Table3.2: Summary of well field production capacity and water level average drops
up to the year 2001 (Source: Haidera, 2007).
Number of
wells
Total
Production
(MCM/yr)
Quantity for Aden
(MCM/yr)
Static level
(m)
Average
Drawdown
(m/year)
Bir Nasser (Lahej)
32
12
11.687
55-65
1.5
Bir Ahmed (Aden)
16
7
5.625
40-50
1
Tuban (Lahej)
19
5
3.263
60-70
2
Rowa (Abyan)
19
12
8.243
12-22
0
Total
86
36
28.818
Well field
The detailed study by Komex (2002) described the distribution of the saline water in
the ground water of Abyan and Tuban deltas, based on existing and new geophysical
data. Contours of the saltwater intrusion front were drawn on the geophysical
interpretation maps for the Abyan and Tuban deltas as shown in Figure (3.3). In their
analysis, they found that in the Lower Abyan delta, brackish to saline groundwater is
interpreted to exist, encroaching from the south, east and west, up to a distance of 12
km from the coast. The deeper part of the saltwater intrusion front, at an elevation of
–400 meter above sea level (masl), is subparallel to the coastline more than 10 km
inland. The front is interpreted to be located at shallower depths as the coastline is
approached up to an elevation of –100 masl. Between this elevation and surface, the
saltwater intrusion front appears to rotate counterclockwise and penetrate further
inland in the eastern portion of the Abyan area (Figure 3.3a).
To get clear idea about the extent of saltwater intrusion into Delta Abyan, line B
profile constructed by Komex (2002), using 1-D soundings from the WRAY report
(1995), and 2- D Electric Resistivity Tomography (ERT) cross-sections A604 and
A603, was adopted in this study. It is a southeast to northwest profile approximately
17.3 km long (Figure 3.4). In the southeastern portion of the profile, low resistivity
values suggest that saltwater intrusion may be present in this layer to a distance of 4
km along the entire profile. Below the alluvium, a sandstone layer is interpreted. This
layer is, probably, laterally continuous, and the lateral variations in resistivity are
thought to be related to groundwater salinity changes from north to south. The
38
a
b
Figure 3.3. Contour lines of saltwater intrusion in (a) Abyan delta, and (b) Tuban
delta (source: Konex, 2002).
Figure 3.4. Resistivity cross-section: Line B Abyan delta (Source Komex 2002).
39
southern end has resistivity values that vary between 0 and 15 ohm-m, and is most
likely an area of saltwater intrusion. The northern end has resistivities that vary
between 40 and 80 ohm-m, reflecting a freshwater aquifer.
It appears that the further inland position of the shallow portion of the saltwater
intrusion front on the east side of the Abyan area is related to incursion of saltwater
along unconsolidated, more permeable sediments, whereas the deeper inland dipping
wedge is contained entirely within consolidated sediments. This is evident on the
eastern side of cross-section line D (Figure3.5). Line D is located in the Upper Abyan
delta area. It is a west to east profile, which is approximately 14.7 km long, and was
constructed using 1-D soundings from the WRAY report (1995). Resistivity values in
the upper part of the eastern side of section range from 0 to 15 ohm-m, and this is
interpreted to be an area of shallow saltwater intrusion. The western end has
resistivity values that range from 40 to 80 ohm-m (Figure 3.5).
The extent of the saltwater intrusion will extend further inland by rising sea level, for
the proposed scenarios of 0.33 and 0.6 m. The interface between the saltwater and
freshwater will extend 160 m and 240 m inland and 16m and 24 m upward,
respectively, effecting the well field in that region.
In Tuban Delta, the boundary of saltwater intrusion is constrained by offset Wenner
soundings and Electric Resistivity Tomography (ERT) data collected during Komex
investigation. It is also supported by observations made in Bir Ahmad well field. Only
the interpreted –50 masl and –100 masl contours are displayed in Figure (3.3b). The
contours are approximately parallel to the coastline, about 10 km inland on the eastern
side of Tuban area. Where the contour lines are close to each other, this indicates a
steep saltwater intrusion front. In the southern portion of the Tuban area, the saltwater
intrusion front is interpreted to be less steep and located within about 5 km from the
coastline. In the west and central portions of the delta, along cross-section line E
(Figure 3.6), brackish water is interpreted to exist at depth. Bir Nasser well field is
located along the eastern side of this section, where possible brackish water deeper
than 150 m is threatening the water quality of this water field. With the rising sea
level of 0.6 m, the level of the intrusion could rise to the well depth and effect the
mean source of ground water of Aden Governorate.
40
Figure 3.5. Resistivity cross-section: Line D (Source: Komex, 2002).
Figure 3.6. Resistivity along the eastern side of section E in Tuban delta (Source:
Komex, 2002).
41
Line G is a southeast to northwest profile in the southern part of the Tuban Delta, and
is approximately 13.6 km long. Resistivity logs from wells 15, 16 and 17 in the Bir
Ahmad well field are also used to construct this cross-section (Figure 3.7). The upper
layer consists of unsaturated silts and sands, which is continuous to the whole length
of the cross-section. It, generally, has a thickness of between 5 and 15 m, and is
characterized by medium to high resistivity, with resistivity values between 60 and 80
ohm-m. The second layer consists of sand and gravel with silt, and is continuous from
3000 m to the end of the profile. It is characterized by resistivity values between 80
and 100 ohm-m, and represents the aquifer from which the Bir Ahmed well field
produces groundwater at a maximum depth of 64 m. A third layer of silt and clay is
found beneath the sand and gravel layer and is continuous from 3000 m to the end of
the line. It is characterized by low resistivities (less than 30 ohm-m). In addition, this
layer may contain brackish water toward the bottom of the section. In the Bir Ahmad
field sands, cobbles are reported in this layer as well. The first 3000 m of the section
are characterized by a saltwater intrusion. The saltwater intrusion front dips
northward, and is interpreted to intersect the bottom of the section at a distance of
5500 m along the line.
Figure 3.7. Resistivity cross-section: Line G Tuban delta (Source: Komex, 2002).
42
Bir Ahmed is an older well field that has been progressively enlarged in extent, and
now contains 25 wells. As it is located closer to the coast than Bir Naser, there has
been concern over increasing chloride content in abstracted water. The data from
NWSA shows a rise in both nitrate and conductivity. Increased conductivity over time
may reflect increasing intrusion of saline water from the ocean, or up-coning if a
wedge of saline water has intruded under the well field. This increasing in
conductivity will be accelerated due to sea level rise.
3.4 Increasing Flood Frequency Probability
Although inundation by increases in mean sea level over the 21st century and beyond
will be a problem for unprotected low-lying areas. The most devastating impacts are
likely to be associated with changes in extreme sea levels resulting from the passage
of storms (Gornitz et al., 2002), especially as more intense tropical and extra-tropical
storms are expected (Meehl et al., 2007). Coastal area would become more vulnerable
to flooding due to mainly four reasons: (i) A higher sea level would provide a higher
base for storm surges to build upon; (ii) Beach erosion would leave particular
properties more vulnerable to storm waves; (iii) Higher water would reduce the
coastal drainage and hence increase the risks of flooding due to rainstorms; and (iv) a
rise in sea level would raise water tables.
Storm surges are temporary extreme sea levels cause by unusual meteorological
conditions. The resulting coastal flooding is a major issue damaging livelihoods,
causing great distress, and in the extreme, loss of life. As many as 2 million people
may have been killed by storm surges in the last 200 years, mainly in south Asia
(Nicholls et al., 1995). Sea level rise will raise the mean water level, and hence allow
a given surge to flood to greater depths and penetrate further inland. Globally, about
200 million people live in the coastal flood plain (below the 1 in 1,000 year flood
elevation) (Nicholls and Hoozemans, 2002). The increased sea surface temperature
would also result in frequent and intensified cyclonic activity, and associated storm
surges affecting the coastal zones (Wu et al., 2002; Unnikrishnan et al., 2006).
The concept of risk is considered appropriate in the context of assessing the
consequences of sea level rise on flooding for the population in the coastal zone. As
rising sea levels intensify flood hazards, some human responses might be expected.
43
Based on the definition of risk, Population at Risk (PaR) is defined as the product of
the population density in a certain risk zone, and the probability of a hazardous
flooding event in this risk zone. The resulting number is interpreted as the average
number of people expected to be subject to flooding events per time unit (year).
Hence, PaR has also been termed as “average annual people flooded”.
As a general approach, the following steps were undertaken in Global Vulenrability
Assessment (GVA) to determine the PaR for the various scenarios (Hoozemans et al.,
1993):

Assessment of the height of maximum flood level theoretically threatening the
low-lying coastal zone;

Determination of the flood prone area and calculation of the area contained
between the coastline and the maximum flood level;

Assessment of the present state of protection against flooding;

Determination of the coastal population densities for the present and future
state; and

Determination of the Population at Risk with and without measures, with and
without sea-level rise, and for conditions in the years, 2004 and 2029.
Sea-level rise and changes in coastal population are unconstrained. In all scenarios,
there are large potential increases in coastal population, which is reinforced by the
assumption of coastal attraction of population. The current population of Aden
Governorate according to the 2004 Census is 598,419, and by 2030, it would increase
to 1.5 million (considering a growth rate of 3.53% for Aden population). The effect of
sea level rise on extreme water levels (i.e. surge height) is an explicit part of the
analysis. Relative sea level rise simply displaces these extreme water levels upwards.
Exposure is measured as a function of the population living below the 1 in 1000-year
storm surge. Following the GVA steps described above, risk is measured using the
average number of people flooded per year in the following section.
In the calculation of storm surges, we follow the method outlined by Nicholls (2006),
where storm surges are calculated as follows:
44
Current storm surge = S100
Future storm surge = S100 + SLR + (UPLIFT × 100 yr) / 1000 + SUB + S100 × X
Where, S100 = 1-in-100-year surge height (m); SLR = sea level rise in meters;
UPLIFT is continental uplift/subsidence in mm/yr (0.16 mm/yr (Peltier, 2004;
Unnikrishnan and Shankar, 2007));
SUB = 0.5 m (applies to deltas only), we don't have deltas in the study area, for that
we take SUB = 0.0; X = 0.1, or increase of 10%, applied only in coastal areas
currently prone to cyclones/hurricanes, also not applicable for our study area.
We calculated surges using data associated with the coastlines, and download
coastline information from the DIVA GIS database. We use the following attributes in
this analysis:
1. S100 = 2.5 m: 1-in-100-year surge height (from GVA data in DIVA).
2. SLR = projected sea level rise (0.33 m, and 0.6 according to the two scenarios)
3.
UPLIFT = - 0.16mm, estimates of continental uplift/subsidence in mm/yr from
Peltier (2004).
Hence, the future storm surge equation in this case well be modified as following:
Future storm surge = S100 + SLR + (UPLIFT × 100 yr) / 1000
For the first scenario the future storm surge will be 2.81 m above the MSL, which is
1.4 m above CD, resulting in the height of the maximum flood level of 4.24 m for the
first scenario and 4.50 m for the second scenario above CD. Accordingly, the flood
prone area, the area contained between the coastline and the maximum flood level
would be vulnerable to storm surge flooding, which could cover most of the coastal
plain of Aden Governorate, including Khormaksar, Al Mansoorah, Al Mua’alla, Al
Buraiqah, the beach between Ras Umran and Foqm. This would effects about 50% of
the populated area of Aden Governorate, where the present average population
density considering that the population is equally distributed, is 800/km2. The
45
population density is expected to increase to 2100/km2 in 2030, considering growth
rate of 3.53%.
This is in consensus with the latest study by (Dasgupta et al., 2009), which considered
Yemen as one of the top five most vulnerable low-income countries with more than
50% of their coastal areas at risk, for exposed populations, and more than 50% of
coastal urban areas lie within the potential impact zones.
3.5 Ecological Impacts
The short duration of this work and limited funding necessitated the use of existing
data sources on wildlife resources and habitat requirements. It is hoped that this study
will encourage future research on coastal wildlife populations and habitat to
incorporate analyses of the impacts of sea level rise and climate change.
Whereas there were limited data on vertical accretion rates for wetlands, Sabkah and
sediment dynamics of beaches and dunes along Aden coastal area, a retrospective air
photos based dated 1975 analysis was conducted for the coastal lagoon in little Aden
(Figure 3.8). These analyses provided insight on how wet land, Sabkah habitats and
beaches have responded to past storms and changes in sea level, as a basis for
considering how they may respond in future.
Aden Reefs, mud flats, wetlands, salt pans and tidelands provide nursery and feeding
areas for many marine species and migratory birds. They considered as an important
staging and wintering area for migratory waterfowl, especially shorebirds, gulls and
terns. The most important feeding area for shorebirds is the mudflats at Khormaksar.
In addition, they also provide important buffer areas for storm protection and to
control erosion.
Wetlands restricted extension further inland was primarily due to the construction of a
road through it since the British colonization of Aden. Also, in the same period, the
building of the causeway across Aden lagoons also changed the hydrology and also
physically destroyed some natural area. These wetlands are particularly at risk where
coastal flood barriers and human settlement prevent their migration inland. As sea
46
Figure 3.8. Khor Bir Ahmed shown in recent Google image, with compare with its
situation in an aerial photography of 1975. Notice the effect of sea level rise on the
salt pans in the first image, as it is almost submerged by sea water.
47
rise, these habitats are subjected to inundation, storm surges, saltwater intrusion, and
erosion. If less sediment is available, wetlands and mud flats that are seaward of the
roads will not be able to maintain appropriate elevations in the face of rising seas.
They will be unable to accrete sufficient substrate as sea level rises, and gradually
altered to inundated area, thereby eliminating critical habitat for many coastal species.
Organisms need specific conditions to thrive or survive. These conditions will be
altered as the climate changes. In wetland, there is a delicate balance between salinity,
dissolved oxygen, turbidity, bottom composition, and temperature. A change in any of
these factors may affect the health and survival of the flora and may also lead to the
death, migration, or ill health of the organisms living among it.
Much of Aden rocky shore habitats dominate in areas with heavy wave action facing
the open water. Rocky shores are areas of bedrock that are exposed between high and
low tide. They are areas of interface between marine and terrestrial ecosystems.
Rocky habitats provide a hard substrate for many marine species. However, this
ecosystem considered at high risk as the intertidal zone shifts with sea level rise.
Organisms that are slow growing or are essentially sessile, such as the limpet during
maturity, may not adapt quickly enough to the pace of a shifting intertidal zone and
subsequently reduce in number. Species are distributed on the shore primarily
according to tolerance of water immersion and emersion.
Intensification in storm activity resulting from climate change could, therefore, create
an unstable environment where sheltered habitats are lost. This would affect breeding
grounds as hiding places for juvenile fish are moved before they have a chance to
grow to maturity, and small invertebrates may be washed away. Increased wind and
wave action could also strip the shore of photosynthesizing flora and therefore affect
the entire food web dependent on them.
The rise in the sea water level eliminates the sandy coastal habitat of Aden and
species dependent on it, such as Ghost crabs, birds and Hawksbill turtle Eretomchelys
imbricata. These animals use the beaches as foraging and reproduction areas and lays
eggs. Such rise will have unfavorably effects since their reproduction areas will
become narrower indicating that sea turtles will suffer the most from SLR. The IPCC
predicts that a sea level rise of 0.5m will eliminate 32% of sea turtle nesting grounds.
48
If sea level rise significantly higher than this over the 21th century, which is expected,
many more vital nesting sites will be threatened.
Turtles are reliant on temperature sex determination, where temperatures of 29.2°C
produce a 50:50 sex ratio in sea turtle populations. Higher temperatures will lead to
the feminization of populations, which will affect breeding success. Hawksbill turtles
depend upon coral reef ecosystems at various stages of their life-cycle. The shelves
and caves formed by coral reefs provide resting and sheltering areas for this species.
Adult hawksbills feed almost exclusively upon reef fauna and rise of reef water
temperature will kill the corals, and its associated fauna, which turtles depend on.
Tropical coral reefs are increasingly threatened by shifts in the world’s climate,
overfishing and declining water quality. However, the changes in the temperature and
acidity rates kill and solidify the corals. The corals bleaching incident in 1997 - 1998,
in the reefs of Red Sea, Gulf of Aden and Socotra Archipelago was due to the
increase in the temperature of the sea water that caused mass death of corals (Abubakr
and Al Saafani, 2006). In fact, death of corals will lead to the destruction of
biodiversity of the seas and causes a decrease in the absorption of CO2, which is
responsible for global warming. As corals provide the basis of reef ecosystems, their
loss will be enormous on the economic value of Yemen (in terms of tourism and
fisheries).
As for crustaceans, the increase in the CO2 amount, this is among the causes of
climate change results in the decline of sea water’s pH, and thus the acidification of
the sea water. This incident will negatively affect the marine crustaceans’ fauna, due
to the dissolving of its calcium carbonate external skeletons by the acidic sea water.
Extinction of these small crustaceans found at the bottom of the nutrition chain can
change the entire sea ecosystem.
3.6 DIVA Model
European project DINAS-Coast (Dynamic and Interactive Assessment of national,
regional and global vulnerability of Coastal Zones to Climate Change and Sea-level
Rise) has developed tools to help policy makers interpret and evaluate coastal
vulnerability. The tool, called DIVA, enables analysis of a range of mitigation and
adaptation scenarios. The project has attempted to predict the global impact of climate
49
change on the coastal zone for the next 100 years, involving a range of mitigation and
adaptation scenarios. The DIVA method uses the project DINAS-Coast database, the
first comprehensive integration of state-of-the-art scientific data, knowledge and
models from climatology, coastal morphology and ecology, economics, geography
and computer sciences.
DIVA is specifically designed to explore the vulnerability of coastal areas to sea level
rise. It comprises a global database of natural system and socioeconomic factors,
relevant scenarios, a set of impact-adaptation algorithms and a customized graphicaluser interface. Factors that are considered include erosion, flooding, salinisation and
wetland loss. DIVA enables user-selected climatic and socioeconomic scenarios and
adaptation policies, on national, regional and global scales, covering all more than
180 coastal nations (McFadden et al., 2004).
DIVA can be applied both globally and at a national scale. The segmentation of the
world's coastline was performed on the basis of a series of physical, administrative
and socio-economic criteria, producing 12,148 coastline segments in total. For sitespecific applications, the model would have to be modified to incorporate local
variables. At this stage, at the national scale, DIVA provides initial perspectives on
vulnerability of the coast to climate change. That requires further development,
including adopting a more customized local-scale coastal segmentation, for use at a
sub-national scale. The coastal area of Aden Governorate was divided by DIVA
model into four segments 1489-1492, which extends from Ras Umran to Al Alam.
The region from Ras Umran to Qa'awa was considered as a part of Lahj Governorate
and covered by segment number 1488.
DIVA model was used to investigate the effect of sea level rise in the costal area of
the Gulf of Aden as an integral way. The output from DIVA was compared with the
vulnerability assessment approach used in this project. Two different cases was
created using two different regional scenarios, which gave two sea level rise
projections similar to that proposed in section 2.6. The input parameters for the two
cases were the same, for each segment, which selected to mach the real situation.
The output from the model shows underestimated result compare with the output of
the vulnerability analysis described in sections 3.1 - 3.5. The expected eroded coastal
50
area was estimated to be 56 ha for SLR of 0.6, and 26 ha for SLR of 0.33 m from the
DIVA run. Whereas, from the vulnerability analysis, the total land loss, due to
erosion, was estimated to be 86 and 48 ha for SLR of 0.6 and 0.33 m, respectively.
Coastal floodplain population were 28,000 in 2010 from DIVA output, while from the
socioeconomic analysis the total population were 67,000 in 2008. The under
estimation of the impacts by DIVA model was due to the coarse resolution of the
input data and also due to the fact that the division of the coastal region into these
segment was not representing the actual situation. For example, segment 1490
represents Al Tawahi Bay, which about 13 km; the length of this segment was 2 km
only.
In despite of the underestimation of the impact by DIVA model, it also show the risk
of the sea level rise on the coastal area of Aden Governorate, as shown in Figure 3.9.
This figure shows the beach nourishment cost for different coastal segments in
Governorate of Aden, where the cost increases from 1.4 million US$/yr in 2010 to 2.6
million US$/yr 2100. The segment location is seen in Figure 3.9b. The cost of see
floods for each coastal segment per year, show that the cost increases exponentially
after 2030 for Khormaksar region till it reach 36 million US$/yr (Figure 3.9c). The
figure underestimates the loss in other segments especially along Al Tawahi Bay
(segment 1490).
51
a)
b)
c)
Figure 3.9. Output from DIVA model. a) The nourishment coast for each segment
along the coastal area of Aden. b) The coastal segments of Aden Governorate. c) the
coast of sea flood in US$ per year.
52
Chapter 4
Socioeconomic Impacts
53
Aden is one of the Yemeni main cities, which have well developed public services.
The water service and electricity networks reach 92% of the houses in the city, and
sewer network is reaching 78.2% houses (Census of 2004).
During the past two decades, Aden has been attracting investments and projects,
which encouraged people to migrate towards it. Aden population increased between
2005 and 2007 by an average of 3.53%, which is higher than the national average
(3.02%). This has activated the construction processes, as about 492 construction
permits have been issued during the last three years (2005 – 2007). The roads
stretched by an average of 4.8%, the communication cables by an annual average of
6.1%, and the educational schools by an annual average of 15%.
The declaration of the Government to make Aden a free trade zone has led to energize
the economical growth of the city, accompanied with good development of
infrastructure and public services projects. Figure 4.1 illustrates the important sectors
among the governorate, and the residential and industrial areas. The massive
development of the expected socioeconomic activities should be steered towards
avoiding the adverse effects on environment produced from those activities. The
evaluation of the expected economic losses in Aden Governorate as a result from sea
level rise (33 – 60cm), was depending on 2008 available data.
The topographic toposheets and aerial photographs of Aden Governorate have been
utilized to build a DEM maps using GIS techniques. Those maps subjected to
different analysis to find out the areas which are likely to be inundated during the
expected sea level rise of 33 and 60cm. This has been followed by ground truth
investigations including visits to the vulnerable sites and confirmation of the elevation
and slope of coastal zone by performing several cross transects along the coasts of
Aden.
The present investigations showed that the area, which are likely to be inundated
when sea level rises are the beaches of Khormaksar, wetlands, and the beaches close
to Aden refineries at Buraiqah (Figure 4.2). The total area of Aden, which is expected
to be submerged with the rise of sea level by 33 cm and 60 cm, would reach about 43
and 45 km2, respectively.
54
Figure 4.1. Map of important sectors in the Governorate of
Aden.
55
Figure 4.2. Map of Aden Governorate showing the expected inundated area due to
the SLR of 33 and 60 cm.
4.1 Houses and Residential Area
The expected submerged area in Aden, when it is subjected to sea level rise, includes
a part of the residential area in Khormaksar, Al Mansoora, and Al Mua’alla Districts,
with a total area of 3.90 km2 at the rise of 33 cm, and 4.35 km2 at 60 cm. From
(Figure 4.3), it’s clearly shown that Khormaksar is the most affected area.
According to the Population, Housing and Establishment Census (2004), the number
of houses likely to be inundated are about 11,482 houses, which are 11.88% of the
total number of buildings in the governorate (Table 4.1). These houses are occupied
by 10,440 families, who are representing about 11.5% of the total number of families
live in Aden. It has been evaluated that about 68,843 persons (about 11.68% of Aden
population), in those places would suffer from Sea level rise.
The total expected losses of the national economy, according to 2008 socioeconomic
situation, because of sea level rise (33 – 60 cm) in Aden Governorate are expected to
be 143,400 million YR. This total loss includes the costs against demolition and
cleaning of constructions in order to covert these areas into new recreational beaches.
56
Figure 4.3. Map of the most sensitive areas of the Governorate,
which area vulnerable to inundation due to SLR of both, 33 and
60cm.
57
Figure 4.4. 3D view of Aden Governorate shows the areas to be inundated by SLR of
33cm.
58
4.2. Land Value
Terrestrial land inundation is considered a loss of part of the national economy
productive fixed assets, in addition to loss of front extension of the State Exclusive
Economic Zone (EEZ). Therefore, submersion of terrestrial land is a real loss for the
national economy in short and long terms. The total loss of land value is estimated to
be around 96,525 million YR.
4.3. Saltpans Area
It was estimated that the total losses of saltpans area by about 2,000 million YR
(Table 4.1).
4.4. Educational Structures
There about 42 educational structures including governmental and private schools and
institutions. According to the information of Ministry of Education, the average cost
of each school with 10 classrooms and their supplementary buildings, is US $ 250,000
(50 million YR). If the costs of construction walls, gates, labs, furniture, etc, are
added, the cost of each school will reach up to 80 million YR. In addition to schools,
there is a vocational training institute, maritime technical institute and trading
institute, which have a total value of 800 million YR. Hence, the grand total losses
because of sea level rise with respect to educational field, might reach approximate
4,160 million YR.
4.5. Health Structures
According to the health facilities survey, sea level rise is expected to attack several
health constructions, including: one hospital, 7 health and childhood and motherhood
centers, and 10 health buildings. The total estimated values are anticipated to reach up
to 11,700 million YR.
4.6. Roads
According to the available information and maps, the total length of roads to be
submerged by sea level rise is approximately 41.33 km. The average cost of
59
Table 4.1. Areas which will be subjected to inundated in Aden Governorate.
District / Area
Khormaksar District
Gazerat Al Omal area
Al Shabat area
Ali Hussain Abdul Nabi area
Al A’awlaqi area
Al Dawh area
Abi Zar Al Ghaffari area
Gamal Area area
Al Ahmady area
Al Gandoh Al Shamali area
Al Gandoh Al Ganubi area
A’abood area
Al Selfador area
Al Dobilain area
Mohammed Nagi area
Molhem area
8 March area
Gazi Alwan Unit
Al Mansoora District
Al Ahmady area
Fadhl Abdullah area
Nagwa Makawi area (50 %)
Raimi Al Gharbiyya area
Al Sena’ah area
Khadeegah area (75 %)
Al Dawh Al Sharqiyyah (50 %)
Al Dawh Al Gharbiyyah (33 %)
Maged Abu Shadr (30 %)
Al Mua’alla District
Aden Port Dock
A’abr and Nagran area
Ben Dahhan area
Ghadega area
30 November area
Mahdy Saleh area
Al Olofi area
Al Salam area
Al Wadea’ah area
Al Ansi area
Omar Ali area
Al Buraiqah District
No residential area is affected
Total
No. of
Houses
No. of
Families
Total
Population
95
86
460
669
353
577
218
395
668
566
140
523
88
328
150
1210
59
73
80
434
592
349
473
137
347
603
552
130
488
90
313
144
1049
14
490
439
3023
4590
2110
2941
819
2127
4260
3926
775
2918
860
2401
1162
7100
126
104
471
229
456
326
485
450
340
69
79
465
212
426
309
464
465
268
65
564
3365
1407
2812
1937
3213
3170
1674
390
5
16
247
399
189
415
104
232
126
130
104
5
16
219
368
165
392
97
221
113
125
98
28
309
1360
2199
387
2391
624
1236
613
672
525
11482
10440
68843
constructing one kilometer of asphalted road is 32 million YR. Hence, the total
amount of losses with respect to roads is expected to be about 1,322 million YR.
60
4.7. Electricity
The losses in electrical energy facilities are expected by losing their infrastructure in
addition to the electrical network to the houses which are going to be inundated.
There are 3 electrical power stations in the area: Khormaksar station, Shenaz station
and Al Mansoora station. The total cost of each is US$ 50 million, US$ 5 million and
US$ 25 million, respectively. The total losses of the electrical infrastructure are
expected to be about 1,600 million YR. One should take into consideration, the
electrical network losses, which amount to about 1,195 million YR, and the losses in
streets lamps are expected to be about 30 million YR. The grand total loss in power
facilities is likely to reach an amount of 17,225 million YR.
4.8. Water and Sanitation Networks
Rise in sea level will definitely damage the water and sewage networking system. All
the systems would be flooded by sea water, as well as the intrusion of salty water into
the water sources. The estimated losses, according to available data, would be US$
1800 for each house affected by the rise of sea level. The total expected losses would
reach up to 4,302 million YR, taking into account that each house is connected with
the networks of water supply and sewage.
4.9. Communications Network
Approximately, the number of telephone lines in Aden is equal to the number of
houses. That means, almost each house has a landline connection. Therefore, with
respect to available data, the total expected losses in communication network are
estimated to be 299 million YR.
4.10. Tourism Structures
Aden, as a coastal city, has become a tourism destination from across the country, or
even from the neighboring countries (Gulf States). The government has been
developing several tourism facilities in order to attract tourists. As the beauty of Aden
is in its natural and clean beaches, almost all the recreational structures and hotels are
concentrated in the coastal area close to these beaches.
61
With reference to the available data; the total expected losses in tourism industry are
approximately 3,800 million YR. This includes the damage expected in the big,
medium and small hotels, as well as the recreational beaches.
4.11. Aden International Airport
Aden International Airport is locating in the most vulnerable area to sea level rise,
Khormaksar. It is surrounded by water from both, southern and northern, sides. Even
it has been necessary to fill up the adjacent wetlands in order to complete the airport
runway structure. In case of sea level rise, the total anticipated losses from subjection
to flooded water are about US$ 500 million, which is equal to 100 billion YR.
4.12. Other Constructions
Excluding all the above mentioned structures, here we are going estimate the total
losses in other constructions. These constructions include: Buildings that are used for
political, cultural, social or economical activities, factories and workshops, clinics and
private hospitals, mosques, shops, poultry farms, etc. These constructions do not
include any of the above mentioned structures, in order to avoid any repetition in
estimated losses.
According to available data, it is estimated that there are total of 23,778 constructions
in Aden Governorate. Approximately 12 % of those buildings are likely to be flooded
by sea level rise, which are accounted to total of 2853 buildings to be flooded. If the
above mentioned structures of health, educational, water and electricity fields are
excluded, the remaining buildings are about 2785. The total expected losses in those
constructions, whether they are small, medium or big buildings, are to reach 25.5
billion YR.
It has been found that the grand total economic losses due to sea level rise by 33cm
are equal to 410,233 million YR (Table 4.2). Whereas, at 60cm rise the losses would
approximately reach 459,461 million YR. As the average annual growth of different
establishments in Aden Governorate is increasing by 1.5%, the expecting economic
losses in 2050 are expected to reach approximately 767,136 million YR.
62
Size of production facilities operating in the governorate of Aden and the anticipated
exposure to flooding due to sea-level rise is 2.8% of the total facilities operating in the
Republic of Yemen. In light of expectations of GDP, which is estimated by 5,723
billion YR, expectations of total GDP until 2050, with an average annual rate of 5%,
and growth reach about 44,410 billion YR. It is, therefore, expected to reach the loss
in gross domestic product for a period of two years to about 2487 billion YR.
Table 4.2. Expected economic losses due to sea level rise (33cm) in Aden
Governorate.
Category
Lands value
Saltpans
Residential Buildings
Educational Institutes
Health Centers value
Asphalted Roads
Electricity Services
Water and Sanitary Sewers
Communication Network
Aden International Airport
Tourism establishments
Other Commercial and Industrial
establishments
Grand Total
63
Losses Amount
(in million YR)
96,525
2,000
143,400
4,160
11,700
1,322
17,225
4,302
299
100,000
3,800
25,500
410,233
Chapter 5
Adaptation Strategies
64
5.1 The Need for Adaptation
Adaptation is processes through which societies make themselves better able to cope
with an uncertain future. Adapting to climate change requires taking the right
measures to reduce the negative effects of climate change (or exploit the positive
ones) by making the appropriate adjustments and changes. Stakeholders play a major
role in defining the appropriate strategy for adaptation to climate change. Finding the
crucial balance between stakeholders’ unique environmental, social, political and
economic interests is dependent upon participation of a wide range of stakeholders,
including residents, community leaders and government representatives, among
others. Each brings unique expertise, insights, priorities and power to the community
adaptation process. In this regards a questionnaire was distributed among wide range
of stakeholders in Governorate of Aden including government representatives,
community leaders, NGOs, scientists and local communities. Their inputs were of
great help in preparing this chapter. Future vulnerability depends not only on climate
change but also on the type of development path that is pursued. Thus, adaptation
should be implemented in the context of national and global sustainable development
efforts.
5.2 Adaptation to Climate Change
The aim of coastal vulnerability approaches is to help coastal communities adapt to
risks of longer-term climate change and accelerated sea-level rise. However, shorterterm impacts of climate variability including extreme storm surges, flooding and
enhanced erosion are also possible risks of future climate change (Clark et al., 1998;
Wu et al., 2002). This is an important distinction in that adaptations of countries and
communities will likely occur in response to changes in frequency and magnitude of
short term, climate variability events rather than gradual, longer-term change in
average conditions such as sea-level rise (Smit et al., 1999).
As mentioned earlier, Yemen has a long coastline of more than 2300 km. This long
coastline makes Yemen one of the most vulnerable countries to climate change and
sea level rise. The high vulnerability of Yemen is attributed largely to its weak
institutional capacity and lack of proper infrastructure, low adaptive capacity, and the
prevailing climate. A number of factors can explain this very low adaptive capacity: a
65
weakening ecological base, poverty, corruption and high dependence on the natural
resource. Improving adaptive capacity is important in order to reduce vulnerability to
climate change. In this regards Yemeni government has to implement effective
strategies to cope with climate change. Effective adaptation strategies come from the
ground up (i.e., from the community affected), rather than from the top down.
Adaptation strategies need to include a wide spectrum of approaches, from policy and
law to engineering and technology. Environmentally sensitive approaches can also be
effective in minimizing change and cost. Raising public awareness and adjusting
cultural values and perspectives can also be cost- and results-effective.
5.3 Adaptation Strategies and Plans
Adapting to climate change will require adjustments and changes at every level from
community to national and international. Communities must build their resilience,
including adopting appropriate technologies while making the most of traditional
knowledge, and diversifying their livelihoods to cope with current and future climate
stress. However, developing countries capacity limitations makes adaptation difficult.
Limitations include both human capacity and financial resources. Outputs from the
UNFCCC workshops and meetings highlighted that the most effective adaptation
approaches for developing countries are those addressing a range of environmental
stresses and factors. Strategies and programs that are more likely to succeed need to
link with coordinated efforts aimed at poverty alleviation, enhancing food security
and water availability, combating land degradation and reducing loss of biological
diversity and ecosystem services, as well as improving adaptive capacity. Sustainable
development and the Millennium Development Goals is a necessary backdrop to
integrating adaptation into development policy.
5.3.1 Current experiences and lessons on adaptation
In spite of the low adaptive capacity of Yemen, the government has developed
adaptation strategy for Aden city to face the great climate internal variability and
extreme events. Aden's coastal zone management strategies and its adaptation plans
was formulated for sustainable management, it suggested 300 m setback for coastal
area, which will help to reduce the vulnerability to climate change. This leads to the
formulation of goals for future coastal zone management concerning sea level rise.
66
The Master Plan Strategy has been undertaken as part of the Port Cities Development
Program to establish a spatial strategy for the long term development of the city and
provide an overall framework for the preparation of infrastructure and sector plans.
An unusually increasing sea level may increase people’s vulnerability in the short
term, but it may encourage adaptation in the medium to long term. This reinforces the
observation that local people have perceived, interacted with, and made use of their
environment with its insufficient natural resources and changing climatic conditions
in what could be seen as practical coping mechanisms. This is particularly true for the
sea level rise prone Aden area, which is susceptible to frequent climatic hazards.
Other strategies are included in table 5.1. According to the IPCC Fourth Assessment
Report, climate change is already happening, and will strengthen even if global
greenhouse gas emissions are curtailed significantly in the short to medium term. This
fact combined with Yemen’s vulnerability to climate change means that planned
adaptation is becoming necessary.
5.3.2 Adaptation requirements
Since climate is changing and climate variability is expected to increase in frequency
and intensity. As mentioned in chapter 3, Aden Governorate is vulnerable to sea level
rise and climate change. Most of the coastal area considered as a lowland region,
which will need immediate protection, especially highly populated regions like
Khormaksar. Other areas, which are less populated, require other type of adaptation
options. Education and awareness formation on climate change among governments,
institutions and individuals should be viewed as a necessary step in promoting
adaptation to climate change in Yemen and especially in Aden. Linking research to
existing local knowledge of climate related hazards and involving local communities
in adaptation decision making. Needing for effective communication between the
supply-side and demand-side communities of climate information in Aden, and the
need to work on means by which climate information can be incorporated into the
livelihood strategies of potential users. Build credibility of rainfall forecasts and
improving their dissemination and use.
67
Table 5.1. Adaptation measures in coastal areas to be highlighted in national
communications of Yemen (modified UNFCCC, 2007)
Reactive adaptation
Anticipatory adaptation
 Enhance the household level and local  Integrated
coastal
zone
communities to participate in the
management plan for Aden is
decisions of environmental changes.
already created and approved in
 Establish early warning systems and
Ministerial Decree.
promoting transfer knowledge and  Better coastal planning and zoning
sharing of experience on adaptation  Development of legislation for
action directly undertaken by those
coastal protection
who are vulnerable, with increase the  Research and monitoring of coasts
cooperation
with
international
and coastal ecosystems
organization.
 Protection of economic infrastructure
 Public awareness to enhance protection
of coastal and marine ecosystems and
promotion of sustainable tourism
 Building dikes and beach reinforcement
 Protection and conservation of supra
littoral vegetation
5.3.3 Adaptation strategy
For the purposes of identifying and reducing vulnerability to climate change, those
areas and activities exposed to rapid environmental changes (e.g., beach erosion,
flooding) and longer term climate changes, should serve as the focus for future work
on developing adaptation strategies. Anticipated impacts and areas of concern for
erosion and flooding hazards, as assessed by the research team, are identified in
chapter 3. Adaptive strategy development, however, was community-driven and
defined, based on the questionnaire in addition to the involvement of the stakeholders
in discussion with research experts. It is also suggested that climate change and sea
level rise impacts to these areas and activities be exclusively considered in future land
use and resource planning and policy development (Walker et al., 2007).
Yemen have ratified the international environmental conventions, namely
biodiversity, climate change and desertification, yet support is still needed from their
development partners to ensure effective implementation of their emerging strategies
68
and plans, as well as to fully exploit the opportunities that could be achieved. One of
the problems facing Yemen in the implementation of these conventions is their
integration into national development programs and establishing synergies and
linkages among them according to UNFCCC requirements. There is also a need for
employing an integrated and synergetic approach among national level development
partners for addressing the requirement of sustainable development (ICZM).
Currently, various national institutions have enacted environmental action plans to
address environmental degradation. Several strategies and plans have been formulated
in Yemen including national environmental action plans, biodiversity plans, coastal
management plans and wetland conservation strategies.
5.3.3.1 Adaptation options for sea level rise
Identification of adaptation options was carried out by designing and administering a
questionnaire based on direct communication with stakeholders in vulnerable areas.
The objective was to collect information and to upgrade the awareness of
stakeholders. Scientific, engineering, and economic evaluations of the obtained
adaptation options were carried out based on pre-specified criteria. An adaptation
decision matrix approach based on cost effectiveness of adaptation measures was also
evaluated. Identifying evaluation attributes is an important topic. The following
attributes were found to be the most important: expenses, net benefits, environmental
impacts, robustness and flexibility, chance of success, feasibility, and fairness. Each
adaptation option will be evaluated based on the above-mentioned attributes
Yemen is considered under the low human development category, characterized by
being highly vulnerable and lacking basic elements for development. In addition to
this, Yemen suffers a lot of poverty-related problems that could directly impact the
human capital (the major pillar in development), including malnutrition and the
increased incidence of epidemic and other diseases. Climate models suggest that
Yemen will be particularly adversely affected by climate change especially seal level
rise between 33 to 60 cm and is expected to lose substantial land, infrastructure, and
tourist revenue along its entire coastal zone area (> 2300 km). This would be an added
burden to Yemen, which is already struggling with lots of vital issues of development
that require urgent attention.
69
The socioeconomic study illustrates the impacts of climate change at Aden
Governorate, caused by sea level rise, concluding that Aden is highly vulnerable to
sea level rise in the absence of protection. However, the total losses caused by 33 cm
above normal sea level, would reach YR 410.2 billion. Part of Al Mansoorah and
Khormaksar will be highly affected during flood and could be lost. It suggests that the
optimum cost–benefit response to land loss due to sea-level rise would be widespread
protection rather than abandoning populated and exposed coastal land.
Adaptive strategies can be classified as “managed retreat”, “accommodation” and
“protection”, which are comprised of a variety of options, as shown in Table 5.2. The
protection option consists of hard and soft technologies: dikes, seawalls, revetment as
a hard one and beach nourishment, wetland restoration as a soft one. The concept
requires an understanding of the entire processes influencing shoreline dynamics to
enable appropriate intervention when necessary. It includes:
I- Set Back
It means allowing space between the shoreline and associated coastal hazard and
property to act as buffer. This measure is most suited for coastal areas that are not yet
developed. Natural buffer should be established between 300-500 m inland, starting
from the high tide. The advantage for such measure is that it enables nature to take its
own course and avoids the need to put up expensive protection with resources, which
are often not available. Even in the event that resources are available, they could be
used for other developmental purposes.
II- Full Protection
The structures include revetments, dikes, sea walls, groins and jetties structures.
Groins that designed to trap sand as it is moved down the beach by the long-shore
drift. Groins are made of rock, wood, or steel. They are useful to retain the sediments
already on the beach or new sand deposited from the nourishment. Dikes and seawalls
are already been practiced in Al Mukalla and Al Hodeidah, however their effect and
designs have to be tested and evaluated.
70
III- Beach Nourishment
Beach nourishment, artificially placing sand on the beaches, is a viable engineering
alternative for shore protection and the principal technique for beach restoration.
Beach nourishment creates a “soft” (i.e., non-rigid) structure by adding sand to make
a larger sand reservoir and a wider beach to effectively dissipate wave energy, thus
not only controlling beach erosion but also providing protection from storm and
flooding damages.
IV- Managed Retreat and Accommodation
There are several options for managed retreat and accommodation strategies. For
example, land-use planning in coastal zones, such as using building setbacks or
allocating low lying vulnerable lands to lower value uses (i.e., parks rather than
housing), will help reduce the overall vulnerability to sea-level rise as well as current
coastal hazards.
Table 5.2 lists the main biophysical effect of relative sea level rise and the possible
adaptation responses. The selection between those responses was done based on the
attribute mentioned above.
Table 5.2. The main biophysical effects of relative sea level rise, including examples
of possible adaptation responses (modified Nicholls and Tol, 2006)
Biophysical effect
1. Inundation, flood and storm damage e.g.
surge (sea)
Possible adaptation responses
Dikes/surge barriers, building codes/flood
wise buildings, land use planning/hazard
delineation
2. Wetland loss (and change)
Land use planning, managed realignment
hard defenses, nourishment/sediment
management.
Coast defenses, nourishment, building
setbacks
3. Erosion (direct and indirect
morphological change)
71
5.3.3.2 Recommended measures
Based on the vulnerability analysis (Chapter 3) and socioeconomic analysis (chapter
4) several regions were identified as vulnerable to sea level rise biophysical impact.
The possible adaptation options for each region are discussed below.
I- Khormaksar - Al-Alam
This coastal area is characterised by lowland sandy beaches extends from Khormaksar
to the boundary between Aden Governorate and Abyan Governorate at Al-Alam. Its
western part is highly populated area and considered highly vulnerable to sea level
rise. The possible adaptation option is building hard protection, Dike, since it is the
only option to protect the highly populated area of Khormaksar. The proposed
structure to build the dike has a typical dimension of 4 m height, 10 m base width, and
2.5 m crown width. The estimated cost of the dike per m cubic is 42 US$ and for one
km is 1.7 million US $. Building a dike along the shoreline of 10 km long will cost 17
million US$. The other constructing option is to rise the existing coastal road of 33 m
width with 4 m high for the dike along the seaside of the road, this will rise the cost to
about 40 million US$.
II-Salt Pans
This region extends from the Marine drive between Khormaksar and Caltex
roundabout till the west, to the region east of the Airport. It is considered as a
backyard of Khormaksar and the coastal region to its east along Abyan beach. The
protection of the region from sea level rise will destroy its value as a respiration
system for the coastal area as local communities name it. It is protected region from
the wave action since the water supply for this region comes from the inner harbour
side. The real risk from the sea level rise and storm surge is for flooding Khormaksar
populated area from this side. The adaptation option for this region can be done by
raising the inner boundaries of these basins by about 2 m, this option will allow them
to continue functioning and protect the populated areas behind it. This protection will
cost about 250000 US$ assuming the length of this region is about 12 km.
72
III- Al Tawahi Bay
Al Tawahi Bay extends between the headlands of Little Aden and Aden, from Caltex
Roundabout to the Farcy Bay. It is characterized by wetland of fine substrates
(mud/fine sands) of low energy. This region is flat coastal area with slope of ~ 2º. It is
vulnerable to sea level rise inundation and flooding from the highland, since it is the
extension for the Tuban valley (Al Wadi Al kabir). The best adaptation option is
setback of ~500 m to allow the rising sea to extend inland. The hard protection will
not be the right option for this region since it will make the region more vulnerable to
the highland flood of Al Wadi Al kabir and will block its connection with the sea. The
difficulty with this option is the inundation of wetland due to sea level rise, especially
for the areas where the constructions and road are close to the coast. These
constructions will not allow the wetlands to migrate inland, which will result to the
loss of the wetland in that region.
IV- The Sheltered Sandy Bay to the West of Ras Foqm
This region is similar to Al Tawahi Bay with fine sand/silt. The adaptation option is
set back between 300-500 m from the high tide. The advantage in this region is that it
still unpopulated area and new constructions should follow these recommendations.
V- The Region from Ras Umran to Qa'awa
This coastal stretch is still unpopulated area, there are no constructions along the
coastline, and it is characterized by sandy beaches with high dunes compare with the
flat coastal plane of the other regions in the Governorate. The appropriate adaptation
option is a set back of 300 m.
VI- The Headlands of Aden and Little Aden
These are rocky beaches and will not be affected by the sea level rise as the sandy
beaches. However, there are several important sandy beaches they enclose, which
would be vulnerable to erosion due to sea level rise. These beaches are valuables as
recreational and tourism sites and the loss of these beaches would affect the tourism
73
sector. The appropriate adaptation option is a retreat for the eroded sand to reduce the
loss for tourism sector.
VII- Managed the extraction of groundwater
As mentioned in chapter 3, the saltwater intrusion into the groundwater of the well
fields of Bir Ahmed and Bir Nasser, would be a threat to the major water supply of
the governorate. It was stated previously (Sogreah, 1981) that by maintaining the
extraction levels at 5 Mm3/yr from Bir Ahmed, 12 Mm3/yr from Bir Nasser and 10
Mm3/yr from Tuban, it would be possible to protect these well fields from
deterioration, high salt content and fast water level drop due to extraction. By
reducing the extraction rate, the balance between the saltwater and freshwater would
reduce the risk of the saltwater intrusion due to sea level rise. This is can be done by
exploring other sources of water supply for the governorate, either from desalination
plants or getting more water supply from other governorates.
Nonetheless, adaptation by protection still leaves large populations at risk from
flooding, when caused by tropical storms and similar events (Nicholls and
Leatherman, 1995b).
5.4 Integration of the Adaptation into National Policy and Planning
After evaluating the vulnerability of the human coastal resources in Aden, there is a
need to define targets for coastal zone management practices. These practices are
concerning sea level rise effects and to provide policy advisers and decision-makers
with some information to support coastal management using the best available
adaptation options.
The evaluation of the coastal zone management strategies, in combination with
intensive literature review, and the results of the sensitivity and vulnerability
assessments described above, form the base for formulation the policy options and
targets for the entire coastal zone of Aden.
Incorporating or integrating climate change adaptation into planning processes is a
necessary strategy for sustainable development over the long term. Climate change
impacts do not happen in isolation. Impacts in one sector can adversely or negatively
74
affect another. Sectors can be affected directly and/or indirectly by climate change
and indeed sometimes a change in one sector can offset the effects of climate change
in another sector. In Yemen, there are difficulties in integrating adaptation concerns
into national policy due to low staff capacity for planning, monitoring and evaluation;
poor data on adaptation options and lack of mechanisms for information sharing and
management across sectors; and limited awareness of adaptation among stakeholders
and the population.
Lack of cooperation among ministries seems to be a major barrier to progress on
adaptation. In order that real progress can be made, key governmental departments
(such as Ministry of Planning and International Cooperation) need to be involved in
the development of adaptation strategies. In the same way, national and local
development planning authorities have to be informed by the relevant outputs of
impact and vulnerability assessments. One positive advance in this regard is the
establishment of the Climate Change High Committee, which involve several
ministries in addition to Environment Protection Authority (EPA). The committee
will help to implement the adaptation options into the development plan.
Environmental and sectoral institutions need to be strengthened in order to be able to
address the complexities of addressing and coordinating the implementation of
adaptation actions. There are a number of actions that can help facilitate adaptation
and integration of adaptation into policy, including actions at the local level (e.g.
strengthening coping strategies and feedback to national policies). At the national
level (e.g. inter-agency coordination in the environmental sector and legal provisions
for mainstreaming) and the regional level (e.g. incorporating climate change risks in
projects of regional development agencies and the creation of intersectoral
committees to be engaged in the formulation of adaptation plans). At the international
level, it was noted that the UNFCCC, other Conventions and other international
organizations could play a catalytic role in exchange of experiences, and in
facilitating the development of region-wide and sector-wide approaches.
Policy and development planners require effective tools and frameworks for
developing, disseminating and building capacity for adaptation and integrating it into
policy at all levels (UNDP, 2004). The legislative changes and recognition by all
government ministries would help facilitate incorporation of climate change
75
adaptation into future policy. The new high committee can help in integrating
adaptation into policy.
5.4.1 Capacity-building
Capacity building at local, national and regional levels is vital to enable Yemen to
adapt to climate change. It is important for stakeholders and sponsors to recognize the
role of universities and research centers. Enhanced support is needed for institutional
capacity building, including establishing and strengthening research centers and
building up hydro-meteorological stations. Training for stakeholders in all sectors
would help the development of specialized tools for planning and implementing
adaptation activities, and thus, promote action by local and national governments
according to UNFCCC (2007).
5.4.2 Education and Training
Education and training of stakeholders, including policy and decision makers, are
important catalysts for the success of assessing vulnerabilities and planning adaptation
activities, as well as implementing adaptation plans. It is important to communicate
both successful and unsuccessful efforts at planning and implementation to avoid
future mistakes. Short policy cycles are a major challenge in keeping decision makers
up to date according to UNFCCC (2007).
Effective training and capacity building needs supports and funding from external
agencies and donors. Training is also needed for models to be effectively applied and
used for assessments at the national or regional level. Promoting better access to
funding and synergy with sources of funding, universities researches have to be
directed and supported to deal with all national concerns in general, and
environmental conservation concern such as climate change in particular.
Collaboration between educational, training and Yemeni research institutions would
help to enable the formal exchange of experience and lessons learned among different
institutions of the respective regions. Universities and research centers have a special
role to play in educating and building the capacity of stakeholders in key sectors.
According to UNFCCC (2007), climate change and adaptation issues should be
integrated into education curricula.
76
Effective international collaboration also helps to enable training on, and structured
dissemination of, international and national activities on adaptation with a view to
retaining experts working in their region, and promoting the exchange of information
between experts from key sensitive sectors. It is also important to assess, systematize
and disseminate knowledge about adaptation measures taken, including indigenous
ones (UNFCCC, 2007). Knowledge and information in Yemen is widely considered
as a personal and agencies properties that cannot be provided to any one outside their
initial owner.
5.4.3 Public awareness
It is essential to involve the Yemeni media in raising awareness of climate change
risks and the need for adaptation should be raised among key sectors and mass media,
using current events, such as economic, weather and health crises, as a basis to
promote adaptation measures with co-benefits. Improving public awareness and
developing overall communications strategies makes targets climate change science
accessible to the average citizen, which can reduce their vulnerability. Besides raising
awareness at local levels, it is also important to involve high-level policymakers to
ensure integration of climate change risks into national development policies
(UNFCCC, 2007).
A communication strategy is an effective way of elaborating and communicating
between knowledge providers and stakeholders on climate change risks and
adaptation needs, targeting actors ranging from those at the grassroots level to the
national and regional policymakers, using appropriate language (UNFCCC, 2007).
77
Chapter 6
Conclusion and Recommendations
78
6.1 Conclusion
Coastal area of the Governorate of Aden was selected as a pilot area for the
vulnerability and adaptation assessment as a part of the Second national
Communication. Range of assessment methods were adopted including stakeholders
involvement, GIS, Bruun Rule and DIVA model. Two plausible future sea level rise
scenarios for Governorate of Aden coastal region gave SLR of 3.3 mm/yr and 5.9
mm/yr. The biophysical effect of SLR includes erosion of sandy shores, inundation of
the low land, destruction of coastal critical habitats, saltwater intrusion into the
surface and ground water, and increases of the flood frequency probability. About 48
ha and 86 ha of sandy shores would be eroded due to the SLR of 33 and 60 cm
respectively. This loss of sandy beaches will affect the tourism and recreation
activities in the coastal communities, especially along Khormaksar, Gold Moor, Foqm
Bay beach and the rest of sandy beaches.
The total land area that would be inundated with the proposed sea level rise of 33 cm
is 43 km2, which represents 5.7 % of the total area of Aden Governorate (about 750
km2). This would increases to about 45 km2 (6%) for SLR of 60 cm. Khormaksar, Al
Tawahy Bay, the coastal beach between Khormaksar and Al Alam (Abyan Coastal
Beach), Aden lagoons and wetlands are the most affected regions. About 3.90 km2
will be inundated in the dens populated area of Khormaksar, Al Mansoora, and Al
Mua’alla Districts for SLR of 33 cm, while 4.35 km2 would be inundated for SLR of
60 cm.
The saltwater intrusion into Delta Abyan, extends to a distance of 4 km of the
southeastern portion of the delta. The extent of the saltwater intrusion will extend
further inland by rising sea level, for the proposed scenarios of 0.33 and 0.6 m. The
interface between the saltwater and freshwater will extend 160 m and 240 m inland
and 16m and 24 m upward, respectively, effecting the well field in that region. In
Tuban Delta, the contours of saltwater intrusion are approximately parallel to the
coastline, about 10 km inland on the eastern side of Tuban area. Bir Nasser and Bir
Ahmed well fields would be affected by salinity intrusion due to sea level rise.
The future storm surge will be 2.81 m above the MSL for the first scenario, resulting
in the height of the maximum flood level of 4.24 m for the first scenario and 4.50 m
for the second scenario above CD. This would effects about 50% of the populated
79
area of Aden Governorate, where the present average population density considering
that the population is equally distributed, is 800/km2. The population density is
expected to increase to 2100/km2 in 2030, considering growth rate of 3.53%.
The output from DIVA was compared with the vulnerability assessment approach
used in this project. It shows underestimated result compare with the output of the
vulnerability analysis. In despite of the underestimation of the impact by DIVA
model, it also shows the risk of the sea level rise on the coastal area of Aden
Governorate.
The total socio-economic loose include loss in the infrastructures, livelihoods. Total
of the houses at risk of inundation under the first scenario are about 11462 houses
(11.88%) in Aden governorate. The grand total economic losses due to sea level rise
by 33cm and 60cm is equal to 410,233 and 459,461 million YR respectively.
Identification of adaptation options was carried out by designing and administering a
questionnaire based on direct communication with stakeholders in vulnerable areas.
The protection option consists of hard and soft technologies: dikes, revetment as a
hard option and beach nourishment, wetland restoration as a soft one. This includes:
set back, full protection, beach nourishment, managed retreat and accommodation.
Accordingly, the coastline of the governorate was divided into six regions depending
on the adaptation options and the topographic nature of that region.
6.2 Recommendations
Adapting to climate change will involve adjustments and changes at every level from
community to national and international. Communities must build their resilience,
including adopting appropriate technologies while making the most of traditional
knowledge, and diversifying their livelihoods to cope with current and future climate
stress.
Most of the coastal area in Aden considered as a lowland region, which will need
immediate protection e.g. dike especially highly populated regions like Khormaksar.
Natural buffer should be established between 300-500 m inland starting from the
highest high tide (HHT) of the country low lands (sandy and muddy coastal areas).
80
Details survey of the important habitats in the coastal area of Aden governorate and
the rest of the country coastal area should be implemented in order to gain better
knowledge about the sensitive areas to the climate change and sea level rise.
To improve the topographic maps of coastal area, Arial survey for entire Yemen
coastal line should be conducted.
Planning and development should not be based simply on historical rates of erosion,
but should add an appropriate additional setback to account for more rapid erosion
over the life of a structure or other development.
To enable workable and effective adaptation measures, ministries and governments,
as well as institutions and non-government organizations, must consider integrating
climate change in their planning and budgeting in all levels of decision making.
It is advisable to define targets for coastal zone management practices concerning sea
level rise effects and to provide policy advisers and decision-makers with some
information to support coastal management using the best available adaptation
options.
Environmental and sectoral institutions need to be strengthened in order to be able to
address the complexities of identifying and implementing the adaptation actions.
Enhanced support is needed for institutional capacity building, including establishing
and strengthening research centers and building up hydro-meteorological stations.
Yemen still need support from their development partners to ensure effective
implementation of their emerging strategies and plans. Effective training and capacity
building, including applicable modeling, needs support and funding, often from
external authorities and donors.
Collaboration between educational, training and Yemeni research institutions would
help to enable the formal exchange of experience and lessons learned among different
institutions of the respective regions. Climate change and adaptation issues should be
integrated into education curricula.
81
It is essential to involve the Yemeni media in raising awareness of climate change
risks and the need for adaptation should be raised among key sectors and mass media,
using current events.
The massive development of the expected socioeconomic activities should be steered
towards avoiding the adverse effects on environment produced from those activities.
Relevant data and information should be made available for all. Monitoring
equipments and stations as a vital toll to follow up the development of climate change
and SLR should be established.
82
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