INTEGRATED ASSESSMENT IN THE PHILIPPINES*
Rodel D. Lasco**
-------------------------------------------------------------------------------------------------------Objectives of the Session
To present and analyze:
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Previous climate impacts assessment on Philippine watersheds (water, forest)
Gaps and limitations of previous assessments
Planned integrated research efforts under AIACC
Future directions for climate change research
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1. Introduction
1.1 Philippines: national circumstances
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An archipelagic nation with > 7,000 islands (1,000 are inhabitable)
Land area: 30 million ha (300,000 km2)
Population: 73 M in 1997
Climate: humid equatorial marked by high temperatures and heavy annual
rainfall (1000-5000 mm)
1.2 Watersheds and their importance
Watersheds are critical to economic development and environmental protection in the
Philippines. More than 70% of the total land area lies within watersheds. There are
421 principal river basins, 18 of which are major basins with drainage areas of more
than 140,000 ha (Cruz, 1998). It is estimated that no less than 1.5 million hectares of
agricultural lands presently derive irrigation water from watersheds. In addition,
hydro-electric power is a major source of energy for the country. There are also
between 18 to 20 million people inhabiting the uplands of many watersheds. Despite
the tremendous value of the watersheds to Philippine economy and its environment,
many watersheds are now in varying stages of deterioration.
2. Previous Climate Impact Assessments of Watershed Areas
Primarily through the US Country Studies Program and the National Action Plan for
Climate Change project, there were initial attempts to study climate change impacts
and adaptation in watersheds. These assessments did not focus on watersheds per
se but were sectoral in nature. The two sectors that dealt with watersheds are the
water resources and forest resources sectors.
*
Case study material used in the AIACC Project Development Workshop, TWAS, Trieste, Italy.
3 June 2002.
**
Professor, Environmental Forestry Programme, University of the Philippines, College, 4031 Laguna,
Philippines. E-mail: rlasco@laguna.net
2.1 Water resources sector
The impacts of climate change were studied in two watersheds: Angat River and
Lake Lanao (Jose et al., 1996; Cruz, 1998, 2002). Rainfall and temperature changes
brought about by a 2xCO2 scenario were projected using three GCMs (CCCM,
UKMO, GFDL). In addition, an incremental scenario approach was also used. Based
on the change of rainfall and temperature, the amount of runoff was predicted using
the WATBAL model (Yates, 1994).
Angat wateshed is a strategic one in the Philippines supplying water for hydropower
(average of 500 GWh per year), irrigation and domestic consumption in Metro
Manila. Results of the preliminary vulnerability assessment for Angat watershed
showed that changes in precipitation and temperature will result in a –15% to 32%
change in runoff depending on the GCM used (Table 1). Results of incremental
scenario showed that the runoff is more sensitive to changes in rainfall than in
temperature (Table 2).
Table 1. Changes in precipitation, temperature, and runoff for Angat water reservoir from
three GCMs (based on 2xCO2)
GCM
Change in Precipitation Change in Temperature
Change in Runoff
(°C)
CCCM
-6%
+2.0
-12%
UKMO
3%
+3.1
5%
GFDL
15%
+2.4
32%
Source: Jose et al., 1996
Table 2. Percent change in Angat water reservoir runoff based on incremental changes in
precipitation (P) and temperature (T)
∆P 0%
∆P 10%
∆P 20%
∆P-10%
∆P-20%
∆T 0°C
0%
8%
18%
-15%
-25%
∆T 2°C
-1%
8%
17%
-15%
-26%
∆T 4°C
-1%
7%
17%
-16%
-26%
Source: Jose et al., 1996
Lake Lanao watershed is another important watershed in the southern island of
Mindanao. Almost all of the GCMs projected increasing temperature and rainfall
(Table 3). The CCCM and UKMO predict lower runoff while the GFDL predicts a 7%
increase in runoff. Just like the Angat watershed, runoff amount is more susceptible
to changes in rainfall than tempearature (Table 4)
Table 3. Changes in annual precipitation, temperature and runoff for Lake Lanao from 3
GCMs (2xCO2)
GCM
RR Ratio
Temperature Change
Runoff Change
(°C)
(%)
CCCM
0.94
2.0
-2
UKMO
1.15
2.6
-12
GFDL
1.25
2.3
7
Source: Cruz, 2002
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Table 4. Percent change in Lake Lanao runoff based from incremental changes in
precipitation (P) and temperature (T)
P0
P10
P20
P-10
P-20
T0
0
-1
4
-2
-17
T2
-2
-1
3
-2
-18
T4
-1
-2
1
-3
-19
Source: Cruz, 2002
Another aspect of earlier work was the generation of adaptation strategies to address
the impacts on water resources. This was done through several meetings where
stakeholders were able to participate. The adaptation strategies recommended are
shown in Table 5.
Table 5 Supply and demand adaptation strategies for the water resources
sector of the Philippines
Supply Adaptation
Demand Adaptation
 Comprehensive watershed
 Enhanced irrigation efficiency
management
 Low water use crops and
 Water allocation system and
efficient farming practices
procedures
 Recycling (reuse) of water
 Improvement of monitoring and
forecasting systems for floods
and droughts
 Water pricing policies and
structures
 Enhanced awareness of
climatic change and variability
Source: Cruz, 2002
2.2 Forest resources
Parellel to the assessment of climate change impacts on waters resources, a similar
effort was conducted for the forest sector. It should be noted that most of the forest
resources of the country are in watershed areas. Thus, while there was no focus on
watershed areas in previous assessments, they were partly covered by the
assessments of water and forest resources.
Under various GCM scenarios, tropical forest areas in the Philippines will likely
expand as temperature and precipitation increase in many parts of the country (Cruz,
1997). The increase in the frequency of droughts and floods due to changes in El
Niño episodes will likely render many areas unfit for agricultural crop production.
Together with the growth in population and the shrinkage of arable lands, the
pressure to open forestlands for cultivation could heighten. Grasslands and other
areas dominated by shrub species could become more vulnerable to fire with
increase in mean air temperature. This could be aggravated if these areas are
subjected to prolong dry periods which is likely under an altered El Niño pattern.
Frequent fires will make these already marginal lands more difficult to rehabilitate.
Temperature change may lead to a loss of a few species of plants and animals that
may significantly erode the biodiversity of these forests. The coastal areas especially
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mangrove forests will be at risk of being damaged by the projected increase in
siltation due to the increase in soil erosion in the uplands. This is on top of the risk of
being completely wiped out by sea level rise. Finally, changes in temperature and
precipitation may result to the outbreak of pests and diseases.
2.3 Gaps and limitations
Considering, the limited resources available then, previous assessments were
understandably general in nature and scope. From a watershed perspective, one of
the main limitations of previous assessments was that they were sectoral in nature.
Totally lacking was a more holistic and integrated assessment of watersheds.
Specifically, there was hardly any attention given to local communities residing in
watersheds. There was also heavy reliance on expert’s judgment in the face of
limited information availability.
3. AIACC Integrated Assessment
Partly to address the limitations of previous efforts, the AIACC-supported study will
attempt to understand the impact of climate change on the whole watershed, i.e.
biophysical systems and local communities. The main approach of the study is
through the use of models backed up by limited field studies and surveys.
3.1 Project objectives
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Assess the impacts of climate change to water resources, forest ecosystems,
and social systems of the watersheds;
Conduct integrated vulnerability assessment of natural and social systems in
the watershed areas;
Develop adaptation strategies for natural water resources, forests
ecosystems and social systems;
Promote stakeholder participation in the research process;
Contribute to peer reviewed literature; and
Help build capacity of local scientists to conduct integrated assessment
studies.
3.2 Project design
The AIACC project originated from an earlier project supported by the Asia-Pacific
Network (APN) headed by Dr. Josep Canadell of GCTE. It was designed by the
principal investigator in partnership with the study team and institutions below.
Philippines: University of the Philippines at Los Baños (UPLB)
Department of Environment and Natural Resources (DENR)
Prof. Dr. Rodel D. Lasco
Prof. Dr. Rex Victor O. Cruz
Dr. Juan M. Pulhin
Atty. Marius Bartolabac
Indonesia: Institute Pertanian Bogor (IPB)
Dr. Rizaldi Boer
Dr. Ekawati S. Wahyuni Ir.
Key Partners
Dr. Meine van Noordwijk
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International Center for Research in Agroforestry (ICRAF), Bogor,
Indonesia
Dr. Josep Canadell
GCTE, Australia
Scientists from Vietnam, Laos and Cambodia
National government agencies, NGOs and people’s organizations
The main clients of the project are those with interest in climate change impacts and
adaptation, including: scientists, policy-makers (DENR, DFA, DA), NGOs and
students in the SE Asian region.
3.3 Methods
The study will focus on a watershed each in the Philippines (Pantabangan
watershed) and Indonesia (Tulang Bawang Watershed). The research framework is
shown in Fig. 1.
Stakeholders will be involved at various steps of the research process through
workshops, meetings and consultations. Local communities will also be able to
participate in impact assessment and adaptation planning.
1. Prediction of landuse and cover change resulting from climate change scenarios
MAGIC-SCENGEN will be used to develop climate change scenarios. MAGICC
(Model for the Assessment of GHG Induced Climate Change) uses a series of
reduced-form models to emulate the behavior of fully three dimensional, dynamic
GCMs. SCENGEN (Scenario Generator) is a simple database that contains the
results of a large number of GCMs experiments. It manipulates data sets based on
the information about the rate and magnitude of global warming supplied by
MAGICC.
Change of land use pattern in the future will be evaluated using the CLUE
(Conversion of Land Use and its Effects) model developed by Peter Veralg at
Wagenignen University.
2. Climate change impact assessment
The impacts of climate change on the bio-physical and local communities will be
assessed through the use of various models such as CO2-Fix for forest carbon and
VIC for water resources. It is envisioned that all of the models will spatially integrated
through GIS.
3. Assessment of adaptation strategies
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Defining objectives: For the selected watersheds these will likely include:
reduction of watershed vulnerability and promotion of sustainable development.
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Identification of climate impacts of importance: This will be the taken from the
results of the previous activity (impact assessment).
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Identifying the adaptation options: This will involve compiling the list of possible
adaptive responses to the impacts of climate change to the selected watersheds.
Aside from literature review, consultations with other experts and stakeholders
will be conducted.
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Examination of constraints: The constraints for each identified option will be
analyzed using literature review and consultations with stakeholders.
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Quantifying the effect of adaptation measure: It will be determined whether the
adaptation measure is able to help meet the stated objectives. Simulation models
could be used to quantify effects on water resources.
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Weighing objectives and evaluating tradeoffs: The relative preference for each
objective will be determined. Then the effectiveness of the various strategies to
meet these objectives will be analyzed. Finally, the preferred strategies will be
selected through the evaluation of tradeoffs analysis.
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Recommending adaptation measures: The set of recommendations will be
packaged in a form that is easily understood by policy makers.
4. Vulnerability assessment
The study will assess the ability of natural and social systems in the watershed areas
to cope with climate change. The analysis will be carried out using analog and
modeling approaches.
Consistent with the APF, this will involve a two-stage process: (a) assessment of
present vulnerability and (b) assessment of future vulnerability.
5. Integrated assessment
The study will seek to integrate vertically (science-policy) and horizontally (across
disciplines) through the use of modeling exercises and non-modeling approaches
(UNEP/IES, 1996). Multi-stakeholder workshops will also be used as a tool in
capturing the views of the various sectors of society including watershed
communities.
3.4 Outcomes
The results of the study will be extremely useful to national policy makers as well as
watershed planners in Southeast Asian countries. The data generated will provide a
firmer foundation in the formulation of policies that will minimize the disruptive
impacts of climate change to water and forest resources. In addition, adaptation
strategies will be put in place that will enable local communities in watershed areas to
adapt to climate change.
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CONCEPTUAL FRAMEWORK OF THE AIACC STUDY (AS 21)
Climate change
scenario
Forest/carbon
budget
Local
communities
Water
Budget
Land use and land
cover change
THE WATERSHED SYSTEM
Socio-economic
political factors
Biophysical
factors
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Table 1 Schedule of activities
Year 1
Year 2
Year 3
Person (s) Responsible
ACTIVITY
1. Kick-off meeting
2. Research implementation
(a) Development of climate scenarios
(b) Prediction of land use/cover change
(c) Impact assessment
(d) Formulation of adaptation strategies
(e) Vulnerability assessment
3. Training for Indo-China scientists
4. Science-policy workshop
5. Report writing/journal paper writing
6. Research team meeting (mid-term and final)
TriestePresentation\rdl
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Lead: R.D. Lasco
Research team
Lead: R. Boer
Research team
Research team
Research team
Research team
Research team
Research team
Scientists from Indo-China
Research team
Policy makers
Lead: R.D. Lasco/R. Boer
Research team
Research team