MALTA’S VULNERABILITY TO SEA LEVEL CHANGE
Emanuel Azzopardi,Ministry for Resourses and Rural Affairs, eazz0005@um.edu.mt,
Ritienne Gauci, Geography Department, Junior College, University of Malta, ritienne.gauci@um.edu.mt
John A. Schembri, Geography
john.a.schembri@um.edu.mt
Division,
Mediterranean
Institute,
University
of
Malta
Abstract
Sea-level rise, as a result of global climate change, is a recognised threat for many continental
countries and islands including those bordering the Mediterranean (Jeftic, L et al, 1996). Studies
dealing with scenarios for changes in sea levels have been estimated for the last half-century
giving ranges from 0.12 to 3.10mm/year (IPCC, 2007a). Estimates for the Mediterranean include
also lower-range and higher-range extrapolations for the next 50 to a hundred years (Attard et al
2004; MRAE, 2004; Tsimplis et al, 2008; and Aldeaneva et al, 2008). These cite figures ranging
from 0.14m to 1.00m. As a result of this situation an island state like Malta, located in the central
Mediterranean, needs to assess its degree of vulnerability to sea-level changes.
The aim of this paper is to present the results of a recent detailed study conducted along lowlying coastal areas. A number of techniques were used to develop the appropriate methodology.
Pilot mapping at 1:100,000 showed the main land-uses, topography and the overall geology and
geomorphology, these assisted in identifying the most vulnerable areas. The second mapping
scale used was at 1:900. This larger-scale mapping focussed on detailed land uses and topography up to the 2.5m level. Vulnerability-Risk assessment using the above information was developed through GIS analysis and inundation maps in the creation of a Coastal Vulnerability Index.
The results obtained were a number of maps overlaying the physical features to the land uses
mapped as well as the Digital Elevation Model (DEM). These presented the different impact that
sea-level rise will have on each of the 29 coastal localities. A second set of maps at the larger
scale (1:900) presents details of three critical localities that were surveyed through land use and
levelling surveying. The results of the Assessment Criteria showed that a new approach at tackling future sea-level rise is needed. This should include detailed studies as shown in this paper,
the use of GIS technology in developing a data-base of information for estimating the socioeconomic, environmental and cultural costs.
1) Introduction
Human populations have always tended to favour settlement along the coastal margin and today
they represent some of the most densely populated regions in the world (87 people per km2 in
2000) (United Nations Environment Programme UNEP, 2006:9). The recent Special Report on
Emission Scenario (SERES) published by the IPCC confirm that by the end of this century the
increase in atmospheric concentrations of GHG’s will cause an average increase in the tempera-
ture of the earth by 0.20C per decade. Research suggest that even if emissions stop today
global warming, CO2 concentration and sea-level rise will continue beyond this century at an
even more accelerated rate The recent Special Report on Emission Scenario (SERES) published by the IPCC confirm that by the end of this century the increase in atmospheric concentrations of GHG’s will cause an average increase in the temperature of the earth by 0.20C per decade. Research suggest that even if emissions stop today global warming, CO2 concentration
and sea-level rise will continue beyond this century at an even more accelerated rate as a result
of the so called ‘‘overshoot’’ phenomenon, in which atmospheric CO2 concentrations rise above
their ultimate stabilization level for some time before being reduced (IPCC 2007a). Early estimates given by scientists at the start of the 1990’s (Bobba, 1999) estimated that global sea levels would rise between a range of 0.5 and 1.5 metres between 1990 and 2100. Today with further advances in modelling the IPCC (2007a) has projected a rise of 0.37±0.58m over the same
time span. This overall reduction is due to the fact that improved models indicate a smaller contribution of glaciers and ice sheets to sea level rise.
These variations between scenarios are also common when it comes to regional assessments.
Manca et al. (2002) claim that paradoxical variations in scenarios, similar to those illustrated in
Table 1 are nothing else but a reflection of the sporadic patterns in the thermohaline properties
of the Mediterranean Sea, yet the different terms taken to analyse sea level changes may possibly neglect the Manca’s et al. presumption. Then again both Aldeanueva’s et al. sea level data
provide some insights for Manca’s et al. presumption, since the same terms were used for both
different areas (Levantine Basin and Balearic Basin). Compared to the MRAE (2004) estimates,
Attard et al. (1996) scenarios are perhaps the most plausible estimate for the Maltese Islands to
date, because of the existing parallelism with regards to the IPCC B1 and A1FI ranges (Table 1).
Mediterranean Sea Level Rise Scenarios
Attard et al. (1996)1
MRAE (2004)2
Tsimplis et al. (2008)3
Aldeanueva et al. (2008)4
Aldeanueva et al. (2008)5
Sea level
change
mm/yr
10mm/yr
-5mm/yr
2050
Low
0.14m
0.5m
High
0.38m
0.5m
0.50m
-0.25m
0.50m
-0.25m
2100
Low
0.35m
1.00m
0.25 m
1.00m
-0.5m
High
0.65m
1.00m
0.51m
1.00m
-0.5m
Table 1: Mediterranean Sea Level Rise Scenarios
1
Principal component analysis utilizing global meteorological variables, 2Eustatic Changes, Sea level rise,
Steric changes, mass addition (continental glacier and Greenland), atmospheric pressure, circulation effect, 4 Levantine Basin - steric and mass induced (continental glaciers and Greenland), 5 Balearic Basin steric and mass induced (Continental glaciers and Greenland).
(Source: Compiled by Author)
3
The concept of vulnerability started to be internationally implemented in the context of sea level
change and Coastal Zone Management in 1991, the time at which the IPCC Coastal Zone Management Subgroup (IPCC CZMS) presented ‘vulnerability’ as the central theme in its
Second Workshop in Perth with the intention of presenting twenty five case studies, each of
which was to asses vulnerability to sea level rise. Despite the advances and the recognition of
the impacts caused by sea-level rise the IPCC CZMS failed to define coastal vulnerability to sea
level changes, going only as far as to say that the factor determining vulnerability is:
Susceptibility of coastal area to physical changes imposed by sea level rise
In 2006 the United Nations Environment Programme (UNEP)
goes further than the IPCC CZMS’ definition and expresses
coastal vulnerability CV as:
CV = f (Exposure to hazard, Population density, Coping capacity)
Though the impacts of sea level change are varied and admittedly uncertain, there is little doubt that adaptive response will
be necessary (Abela, 1999). Up till two decades ago, sea level
rise was not perceived as a potential threat for the coastal zone
and prior to 19911 the term ‘vulnerability’ was limited to studies
about hazard management of hurricanes, volcanoes and earthquakes (Turner, 1996).
The IPCC’s methodology, better known as ‘The Common Methodology’ was specifically designed in 1992 and subsequently
modified up to 2007, to address the effects of sea level rise and
is carried out in seven analytical steps as illustrated in Figure 1.
The strengths of this methodology lie in its wide operational approach, which deals with the complexities in the field and dynamism of the coastal margin (Abela, 1999).
Abela (1999) argues that, flexibility makes impact assessment
studies a decisive tool when it comes to quantifying and qualifying the risk factors to which coastal lowlands are exposed, particularly due to the uncertainties in the predictions of time, magnitude and regional patterns of sea level change impact, as well
as the numerous secondary impacts of this phenomenon (UNFCCC, 2008c)
on Method2, 2007)
The setting up of the Environmental Protection Directorate in MEPA (formerly known as Planning
Authority) in the late 2000, addressed the need for a single Environmental Protection Authority
under the Ministry for Resources and Rural Affairs. This directorate, particularly the Integrated
Coastal Zone Management (ICZM) sector, was assigned specific responsibilities for the estab1
In 1991 the IPCC CZMS workshop
lishment of environmental standards and the management of activities which have an impact on
the natural resource. The policy network created shows the present day organisational structures for MEPA and other departments that influence the coastal zone. Many a times these organisations work independently from each other, however an effective ICZM implies that all of
these organisations should continuously share data to coordinate policies towards sustainable
along the coast (MEPA, 2006a).
2) Coastal Vulnerability Index
The Coastal Vulnerability Index has been set up to: quantify risk, identify the factors that increase vulnerability along the coastline and to determine the extent to which certain coastal areas might be more vulnerable than others. The indicators to assess vulnerability were adapted
from preceding studies carried out by UNEP (2006) and Abela (1999). The reasons for adopting
these indicators are two: first is that these indicators allow the incorporation of qualitative indicators for which no numerical data is available and second is that the range of indicators (socioeconomic and physical) is varied, thus the exact factors which increase vulnerability along the
coastline can be effectively determined.
The adapted sets of indicators are displayed in Table 2. The Coastal Vulnerability Index developed here will be based on a combination of physical and socio-economic indicators in order to
create a composite index, incorporating a comprehensive assessment of the risks of relative sea
level change in single-figure format.
Type of Indicator
Indicator
Description of Indicators
Physical
SocioEconomic
·
·
A
Land Use Diversity (Units: Frequency)
B
Area of land composed of Land uses which require a coastal location for its
operational needs and below the one-metre contour line (Units m2)
C
The proportion of the protected ecological and cultural areas under the onemetre contour line (Units: per cent)
D
Geographic Exposure – Socio-economic assets (Units: m2)
E
Geographic Exposure Units – Physical assets (Units: per cent)
·
F
Physical and socio-economic assets at risk of inundation (Units: Index Number)
·
·
·
·
·
Table 2: List of Indicators to show whether the criteria used were physical, socio-economic or both.
·
Source: Adapted from UNEP (2006) and Abela (1999)
3) Spatial Distribution of Socio-Economic and Physical Assets
Since it is suggested that height above sea level is not the sole factor that determines vulnerability (UNEP, 2006), further analyses were made such as the vulnerability scores of each locality
that were obtained for all indicators (Table 2). Initially these scores were summarised in a dendogram (Fig. 3), the aim of which was to identify other factors that assess vulnerability. Based
on the Euclidean distance amongst the six indicators, two main clusters can be observed: Indicator B with D and Indicator E with F.
The common denominator responsible for the similarity between indicators B and D was noted
to be the same scoring obtained in most localities: in fact twenty-one out of twenty nine localities
scored the same values – five localities with a score of zero (0), eleven with a score of one (1),
three with a score of three (3), one with a score of (4) and the remaining locality of Birzebbuga
with a high score of five (5) in both indicators.
This existing similarity (75% similar) between indicator B and D emphasise the fact that the
presence of coast-dependant land uses are other factors which determine vulnerability besides
height above sea level. Thus if a locality has a considerable number of socio-economic activities
which are coast-dependant, it is likely to be more vulnerable to sea level rise. This relationship
is typified by the locality of Birzebbuga where a vulnerability score of five (5) was obtained in
both indicators, and it was mainly influenced by the large area (389087m2) of the Freeport. The
total area of coast-dependant land uses below the one-meter contour line in the Maltese Islands
was noted to be of about 69 percent.
The second cluster (Indicator E and F) share a common denominator which is quite different
from the previous cluster. In the above-mentioned sections it has been noted that Indicator E is
responsible in identifying the length of coastline which is made up of unconsolidated material
and low-lying coast below the one-metre contour line, while Indicator F determined the impact of
sea level rise (0.58m) on the relevant land uses in each locality. Thus given that Indicator F is
only linked with Indicator E and no indicators that are responsible for socio-economic activities
below the one-metre contour line (e.g. Indicator B and D), it can be concluded that low-lying
physical factors (e.g. shore platforms and sandy beaches) are more influential in relation to vulnerability levels than socio-economic land uses. An example of this is typified by the locality of
Mellieha where a score of five (5) was obtained in both indicators (E and F), which has been
highly influenced by the large unconsolidated material at Ghadira Bay.
Fig 3 Dendogram of the Six Vulnerability
Indicators (A-F
Source: Developed by Author from the resultant
Coastal Vulnerability Indices (Table 2)
Fig 4 Dendogram of the twenty-nine Coastal
Localities
Source: Developed by Author from vulnerability
scores of each locality for all indicators
Figure 5 High-risk localities in red; medium risk in
yellow; low risk in beige.
However the dendogram suggest that the second cluster is less similar (50% similarity), in fact
only seventeen localities scored similar values for both indicators. These localities are subdivided as follows: thirteen localities score a similar value of zero (0), one with a score of one (1), two
with a score of three (3) and the remaining locality of Mellieha with the highest vulnerability
score of five (5). Moreover the similarity of this cluster has to be attributed to the fact that most
indicators were not applicable in thirteen sites and this is mostly related to the limited presence
of unconsolidated material (2%) and relatively low-lying shore platforms around the Maltese
coast.
Ultimately, given that the presence of sandy beaches and the relatively low-lying shore platform
are limited, it can be stated that coastal vulnerability around the Maltese coastline is predominantly influenced by the presence of socio-economic assets (mainly coast-dependant assets).
In fact the latter is confirmed through the Spearman Rank Correlation Test which shows that
there is a strong positive correlation of 0.98 between the Coastal Vulnerability Indices (Table X)
and the amount of coast-dependant land uses (Indicator B), whereas a lower positive correlation
(0.65) was noted between the Coastal Vulnerability Indices and the presence of sand and relatively low-lying shore platforms in the coastal zone (Indicator D).
4) Causes of Vulnerability
As seen in Figure 4 an of the localities within a range of vulnerability. In turn these groups suggest that high vulnerability is determined by abundant and diverse scores amongst all indicators.
Based on the Euclidean distance, six clusters can be observed amongst the twenty-nine coastal
localities (Fig. 4): Marsaxlokk with St. Paul’s Bay - Kalkara with Pieta’ – Pembroke with St. Julian’s - Floriana with Cospicua – Qrendi with Sengela - Zabbar with Zurrieq, Siggiewi, Dingli and
Rabat.
Fig 6 Three critical localities that were surveyed through land use and levelling surveying
Source: Developed by Author from the resultant Coastal Vulnerability Indices (Table 2)
The first cluster illustrates two localities (Marsaxlokk and St. Paul) which have obtained a high
vulnerability index (CVI: 4.33 and 4.17 respectively). The common denominator which delineated a similar type of vulnerability in this cluster was the same and high vulnerability scoring obtained in three indicators (C, E and F). Initially indicator C illustrates that both localities have the
same level of vulnerability (5) in light of important ecological areas (Simar at St. Paul’s Bay and
Il-Ballut Salt Marsh at Marsaxlokk). Further similarity is brought out in indicator F which illustrate
that the effect of inundation is equally shared to both areas (5), while indicator E suggest that a
certain degree of similarity has been demarcated by the same length of physical assets (e.g.
low-lying shore platform) below the one-metre contour line. Despite their similarity (Fig 4), the
final value for their coastal vulnerability was marginally different: 4.33 for Marsaxlokk and 4.17
for St. Paul’s Bay. The higher value for Marsaxlokk is to be attributed to the presence of coastdependant land uses (Indicator B) and the greater land use diversity in its coastal low-lands (Indicator A).
The common indicators which delineated the second cluster (Kalkara and Pieta) suggested that
vulnerability to sea level rise in Kalkara and Pieta’ has been determined by socio-economic land
uses in their coastal low-lands. In fact Indicators A, B and D and the related raw data confirms
this and suggest that maritime activities and road infrastructure are the main features which
augment vulnerability in both localities. Further similarity is highlighted by the large presence of
cultural areas below the one-metre contour line such as Military Architecture: Bighi, Military Lift
in Kalkara and Maritime Architecture – Customs House in Pieta’.
The dendogram (Fig 4) shows that Floriana and Cospicua share a high degree of similarity,
which is based on the same scoring obtained in all indicators. Yet, the main factors which increased vulnerability in both Floriana and Cospicua is mainly dominated by the presence of
coast-dependant land uses: concrete platforms, which are relatively more important towards
Malta’s economic development, amongst which one can locate the Cruse-liner Berths at Floriana and the Dockyard concrete platforms at Cospicua.
The common denominator for the Qrendi and Senglea cluster is the similar to the previous (Floriana-Cospicua). However since the concrete platforms are smaller in form and of lesser importance, a lower vulnerability index (0.51) was obtained. Another cluster was noted in the dendogram (Fig. 4). This is made up of 5 localities (Zabbar, Zurrieq, Siggiewi, Dingli and Rabat)
where the CVI of each was noted to be zero (0.00). This high similarity (100%) has to be mainly
attributed to the fact that all indicators were not applicable for these sites and this is mainly related to the limited number of developed low-lying areas and the relatively higher topography as
in indicated by the bar graph (Figure 5 and 7 respectively).
Plates 1-2: Examples of marine waters invasion in St Julian’s bay and Birzebbuga
Figure 7 Impact of sea level rise Indicator F
Source: Developed by Author from GIS database, Coastal Topic Paper (P.A., 2002) and National Report on ICZM (MEPA, 2006)
5) Conclusion: Proposed Strategy for Coastal Vulnerability Assessment
Some of the suggestions put forward by Abela (1999) expounded on the fact that Malta should
adopt vulnerability studies consistent with coastal zone management practices, irrespective of
whether sea level change occurs or not. On the other hand, despite the fact that the threat
posed by climate change has up till now not been recognised in coastal zone management
practices, the results suggest that even if sea level rise would not reach the predicted levels
(0.58m) as endorsed by the IPCC, a slight increase in sea level would still leave significant impacts in the coastal zone. This increase in sea level will reduce the capacity of water grills to
transport storm water and would shift the base level of the hydrological and culvert system further upstream (cf. Plates 1-3)
These problems would be very significant in low-lying coastal areas that are located at the
floodplain part of the major valley systems. Thus considering these implications, current situations at many localities such as Msida catchment will continue to aggravate and temporal flooding level will increase significantly.
Therefore any framework for coastal adaptation must be coordinated with the instructions and
criteria as stipulated in the Floods Directive 2007/60/EC. The purpose of this Directive is to
manage and reduce the risk of floods, particularly along rivers and in coastal areas. Being a
member state, Malta is obliged to prepare preliminary flood risk assessment for each river basin
and coastal areas to show an appraisal of the potential risks. In fact this Directive enforces
Member States to:
“draw up maps to identify all areas posing a risk of flooding and indicate the probability (high,
medium or low) of flooding for each areas and the potential damage for local populations, property and the environment ....... and .............these maps must be drawn up and published by the
22 December 2013 at the latest and reviewed every six years”
This allows a systematic examination of a country’s coastal vulnerability to both sea level
change and storm flooding events. The proposed model is designed in a comprehensive way
as possible by encompassing all the steps which are necessary not only to give a complete picture of the country’s coastal vulnerability capacity, but also to establish the range of actions required to reduce the coastal vulnerability vulnerability to both sea level change and storm flooding events. The proposed model is designed in a comprehensive way as possible by encompassing all the steps which are necessary not only to give a complete picture of the country’s
coastal vulnerability capacity, but also to establish the range of actions required to reduce the
coastal vulnerability (Azzopardi, 2009).
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