Working Paper 1:  Carbon Budgets of Terrestrial Ecosystems in the Pantabangan-Carranglan Watershed

Lasco, R.D., Pulhin, F.B., Cruz, R.V.O., Pulhin, J.M. and Roy, S.S.N. 2004. Environmental Forestry Programme. College of Forestry and Natural Resources.  University of the Philippines Los Baņos, Laguna. Philippines.

This paper reports on research supported in part or in whole by grant number AS21 from Assessments of Impacts and Adaptations to Climate Change (AIACC), a joint project of START, the Third World Academy of Sciences, and the UN Environment Programme. Comments are welcome and should be sent to the corresponding author.

ABSTRACT

Climate change is predicted to affect forest ecosystems. One of the uncertainties yet to be resolved is the impacts of climate change on carbon budgets of forest ecosystems. This study provides baseline information on the carbon stocks of the Pantabangan-Carranglan Watershed  (PCW) in preparation for impacts and vulnerability studies.

Current carbon stocks in above-ground biomass, necromass and soil were determined using field measurements and laboratory techniques. Total carbon budgets over time of natural forest ecosystem were simulated using the CO₂-Fix Model.

The study shows that natural forests have a carbon density of 300 and 563 MgC/ha in aboveground biomass and necromass using the Powerfit equation and Brown (1997) equation, respectively. Brushlands and tree plantations have lower carbon densities (generally less than 200 MgC/ha) while grasslands have less than 20 MgC/ha. Total above-ground carbon stocks of the whole watershed is estimated to range from 4,800 to 8,900 MgC depending on the biomass allometric equation used.

The results of simulation showed that while carbon in forest biomass is increasing over time by about 50 MgC per century in the PCW, the soil organic carbon was declining by roughly a similar amount. Thus, overall, the total carbon density remains stable over time after an initial decrease.

The potential of the watershed for carbon sequestration through tree establishment in open areas is highlighted.

Working Paper 2:  An Assessment on Social Vulnerability to Climate Change in a Time of Renovation: A Case Study in Giao Thuy District, Nam Dinh Province, Vietnam.

Luong Quang Huy and Ngo Cam Thanh. January 2004. Working paper for the Environmental Forestry Programme, University of the Philippines Los Baņos, Laguna, Philippines.

Paper submitted to Assessments of Impacts and Adaptations to Climate Change (AIACC), a joint project of START, the Third World Academy of Sciences, and the UN Environment Programme. Comments are welcome and should be sent to the corresponding author.

EXECUTIVE SUMMARY

Understanding the capacity of a society to cope with global environmental change is critical, especially in a developing and vulnerable country like Vietnam. The study aims to assess the changes in social vulnerability and resilience under the effects of economic renovation in Vietnam and the implications for local society coping with the impacts of climate and weather extremes in Giao Thuy district, Nam Dinh province in the north of Vietnam. A set of vulnerability indicators has been selected and tested in the study.

The economic renovation – doi moi - promulgated in Vietnam since the mid 1980s has affected the rural society. Social livelihoods have changed, of which aquaculture shows a fast rate of development since the introduction of doi moi. The newly introduced livelihoods have increased the level of income and of welfare inequality within the local community. Though these newly introduced livelihoods have richened the community, only the better-off, who can afford to invest in the new livelihoods, can gain the major benefits.

Income and welfare inequality has led to some consequences, spontaneous migration and labour reallocation. Increasing demands for manual works in urban areas has attracted men from the local region. This trend has increased the remittance income and limited the loss of resilience associated with greater level of inequality. However, along with spontaneous migration, labour reallocation has also caused a lack of local employment and weakened the social structure. This has not improved the level of social resilience. Under these consequences, the coping capacity of local community to deal with climate and weather extremes has been altered. An analysis of how the different groups cope with climatic change shows the imbalance amongst the groups within the community.

The study has analysed and tested a set of indicators reflecting the level of social vulnerability and resilience of different groups within the community. Results showed a complexity in effects and local response. From these findings, policy implications to promote greater resilience have been proposed. Further research opportunities are also discussed.

The study was based on data collected during projects within the Red River Delta / Global Change Programme of which the authors are members. Part of this study was undertaken during the period of 2000-2001, which is clearly stated hereinafter in this paper. The in-depth analyses, discussions and interpretations have been undertaken by the authors alone, unless otherwise noted

Boer, R. and Faqih, A. January 2004. Climatology Laboratory Faculty of Jl. Raya Pajajaran Bogor.

Paper submitted to Assessments of Impacts and Adaptations to Climate Change (AIACC), a joint project of START, the Third World Academy of Sciences, and the UN Environment Programme. Comments are welcome and should be sent to the corresponding author.

Current and future rainfall variability in Indonesia was described.  From historical data, it was suggested that seasonal rainfall tended to increase in some regions and decrease in other regions.  A spatial analysis of monthly rainfall means of over 210 stations throughout Indonesia, which are divided into two periods, i.e., 1931-1960 and 1961-1990, was performed. Results showed that annual rainfall in most of the area in the southern regions (e.g., Java, Lampung, South Sumatra, South Sulawesi, and Nusa Tenggara) has decreased, while it increased in the northern part (e.g., most of Kalimantan, North Sulawesi).  The difference between wet season (seasonal rainfall during September to November and December to February) and dry season (seasonal rainfall during March to May and June to August) increased.  For the southern region, the wet season rainfall tended to increase, whereas the dry season rainfall tended to decrease.  The opposite pattern was observed in the northern region. 

Many of extreme climate events in Indonesia were often associated with ENSO phenomena, i.e., La Niņa and ElNiņo. El Niņo was normally associated with drought (decrease in rainfall), while La Niņa was associated with flood (increase in rainfall).  However, the effect of La Niņa on rainfall increase was not as strong as the effect of El Niņo on rainfall decrease.  The effect of the ENSO events was strong in regions strongly influenced by monsoon system, weak in regions that have equatorial system, and not clear in regions that have local system. Rainfall pattern strongly influenced by monsoon system is uni-modal (one peak of rainy season), six months receive high rainfall (called rainy season, in general from October to March; some regions have longer dry season, particularly the eastern part of Indonesia such as Kupang), and other six months receive less rainfall (called dry season, in general from April to September).  Rainfall in Indonesia regions is dominated by this monsoon system. Rainfall pattern in regions strongly influenced by the equatorial system is bi-modal (two peaks of rainy season, normally occurs in March and in October).  And rainfall pattern in regions strongly influenced by local system also has uni-modal rainfall but the pattern is the opposite of the monsoonal type.  A number of studies suggested that how global warming would affect ENSO was not clear.

Based on analysis of a number of GCM models outputs using two scenarios, i.e., high (SRESA2) and low scenarios (SRESB2), it was suggested that the under changing climate means of Indonesian temperature will increase at a rate of about 0.0344 ^oC per year for SRESA2 and about 0.0211^oC per year for SRESB2.  The impact on rainfall varied among GCM models and between the scenarios.  The CCSR and CSIRO suggested that the seasonal rainfall would increase consistently in the period between 2020 and 2080 under both scenarios, except for SON (Sept.-Nov.) rainfall.  Whereas, for ECHAM4 and CGCM1, the rainfall would decrease consistently while for HadCM3, the impact was not consistent.  For example the DJF (Dec-Feb) rainfall, it might not change up to 2020, but it would increase up to 2.5% from the baseline in 2050 and then decreased up to 2% from the baseline in 2080.  Regions with decreasing rainfall might be exposed to high drought risk (long dry spell), while those with increasing rainfall might be exposed to high flood risk.  The return period of such extreme events might also increase. This study indicates that the impact of global warming on rainfall in Indonesia could not be generalized.

Key words: rainfall variability, El-Nino, La-Nina, rainfall change and GCM,

Working Paper 4:  Hydrology Balance of Citarum Watersheds under Current and Future Climate

Boer, R., Dasanto, B.D., Perdinan and Marthinus, D. January 2004. Laboratory of Climatology, Department of Geophysics and Meteorology, Bogor Agricultural University.

Paper submitted to Assessments of Impacts and Adaptations to Climate Change (AIACC), a joint project of START, the Third World Academy of Sciences, and the UN Environment Programme. Comments are welcome and should be sent to the corresponding author.

ABSTRACT

Citarum is the biggest watershed in West Java. It plays an important role in supplying water for many districts in West Java. It can supply about 7,650 MCM (million cubic meters per year) where about 5,750 MCM come from Citarum dams (Saguling, Cirata and Jatiluhur) and about 1,950 MCM come from other rivers (Perum Jasa Tirta II 2003). At present about 78% of the water is used for irrigation, 14% for industrial activities and electricity generation, and 8% for domestic consumption. This watershed was found to be very vulnerable to climate change. At present, under the condition of no changing climate and if level of water extraction from the stream flow were limited to 10% of the mean annual flow, it was found that all of sub-districts already have water deficit problem, particularly in the lower areas in a number of sub-districts of Kerawang, Bekasi and Purwakarta. Level of water deficit in these sub-districts would be more than 60 MCM per year. When rainfall increased by 10% or 20% from present condition, the water status of the Citarum would still be not enough if the level of water extraction were kept at 10%. More areas in these districts would have severe water deficit problems as the year moves forward. In 2080, level of water deficit for most of sub-districts in this lower area would be more than 60 MCM. Increasing water extraction to 20% would not change the water status of these sub-districts even though the water demand scenario was changed to follow SRESB2 from IPCC (lower population growth rate). However, when rainfall was increased by 20% and level of water extraction was also increased to 20%, water balance status for most of sub-districts in the watershed would be more than sufficient until year of 2020, but again sub-districts in the lower areas will remain deficit with lower intensity, i.e. between 0-30 MCM. It is expected that the level of water conflict in the future may increase.

Key words: Hydrology balance, Citarum Watershed, climate change.

Working Paper 5:  Assessing the Impact of Land Use Change and Climate Change on River Flow at Citarum Upper Catchments

Boer, R., Perdinan, Delon and Faqih, A. January 2004. Laboratory of Climatology, Department of Geophysics and Meteorology, Bogor Agricultural University.

Paper submitted to Assessments of Impacts and Adaptations to Climate Change (AIACC), a joint project of START, the Third World Academy of Sciences, and the UN Environment Programme. Comments are welcome and should be sent to the corresponding author.

Managing upper catchments area of a watershed in sustainable way is very important to support living of many ecosystems in the watershed. In the context of water management, converting forest to other uses in the upper catchments area without careful supervision will result in increasing runoff to an alarming level. This will increase the flood risk during rainy season and drought risk during dry season. These risks may increase under changing climate. From dialog between stakeholders and scientist at Bandung, it was suggested that at least 40% of watershed area should be maintained as conservation zone (forest cover). Under this condition, it is expected that impact of climate extreme events and possible climate change can be minimized. Ecological function of the watershed can also be revitalized and in turn it will improve quality of life of the people (Bapeda Jawa Barat 2001).

Protecting watershed without good participation of local community and other related stakeholders might not be successful. Therefore, the policy of local government for managing the watershed will focus on how to involve stakeholders in the process of setting up land use planning (participatory planning). This approach could accommodate various interests, minimize conflict between sectors and districts, and importantly it will create social control to any effort for using the land (Bapeda Jawa Barat 2001).

Studies to assess impact of forest cover change on river flow will be required in the process of setting up land use planning. Many attempts have been done, however, the works are largely independently of climate change (Arnell et al. in IPCC 2001). Considering climate change in assessing impact of land use and forest cover changes on river flow is very important for developing long-term water management planning. This will assist policy makers in assessing impact of changing land use policy on water sector under different plausible climate changes. This technical paper describes (i) land use changes in upper catchments area of Citarum watershed, (ii) simple approach to downscale GCM output, (iii) generation of daily climatic data from monthly GCM outputs, (iv) evaluation of hydrology model, VIC Basin, and (v) assessment of impact of changing land use in the upper catchments area of Citarum watershed on river flow under different climate change scenarios.