Using the DSF to assess scenarios Some things it will do for you - and some things it won’t

Example Scenario: Stung Treng Hydropower Dam Scenario: hydropower dam at Stung Treng –assume that the size and operating rules of the dam are given What can the DSF tell us about the outcomes in terms of –hydrology –environment –social impacts –economic impacts Option 1

Hydrology DSF tells us LOTS about hydrology –changes in flow patterns at different places due to dam –flow impacts for different operating rules –changes in flood extent and frequency

Hydrology - existing flow conditions at Stung Treng

New flow conditions after dam construction - Stung Treng Fake Data

New flow conditions after dam construction - Kratie Fake Data

Current major flood extent

Major flood extent with dam Fake Data

Flooding DSF gives changes in extent and duration of flooding, and information about the type of land flooded (land use, wetland type) NO information on impact on ecosystems impact on fish production value of reduced damage from floods ….etc Consult an expert! Flooded area (ha) Trey riel catch Before dam After dam

Environment - wetlands GIS in DSF gives location of wetlands, and some information on type NO information on response of wetland plants or animals to changes in flow how changes would affect subsistence use value of wetland produce and how this would change Consult an expert! (or wait for EP flow management program)

Social Impacts GIS in DSF gives location of villages population some information on social conditions (from Census, provincial level) NO information on subsistence livelihoods resettlement options and preferences cultural values ethnic minorities …..etc Consult an expert!

Economic impacts GIS in DSF gives some information on land use, irrigation NO information on value of ag production non-agricultural industries value of power generated costs of relocation Consult an expert!

Using the DSF BDP will need to consider MANY scenarios Large number of exploratory runs to establish major hydrological patterns / constraints –Analysis mainly of hydrological outcomes Smaller number of “full” runs –Include social and economic analysis –much of social and economic analysis will take place outside the DSF

Scenarios Scenarios are descriptions of possible futures –help us to test and compare possible outcomes of different decisions For BDP, scenarios describe possible changes to the water resources system over the next 5 to 20 years

DEVELOPMENT SCENARIOS PLANNING SCENARIOS BASELINE SCENARIO Scenarios Available water resources –supply, demand / use, condition Trends affecting water resources – predictable (population growth) – uncertain (economic conditions, climate change) Possible interventions and developments – structures, management practices

Impact analysis Impacts of different scenarios are described using expert opinion and models (DSF) –hydrological –environmental –social –economic Impacts may be poorly understood / little data available / difficult to quantify –particularly for social and economic impacts –work with existing knowledge –qualitative / descriptive vs quantitative DSF DSF and other sources

Assessing Scenarios Outcomes of different scenarios are assessed and compared against regional planning goals using assessment criteria and indicators / targets –does the scenario meet development goals? –does it obey WUP Rules? –are key Basin assets protected (fisheries, water quality)? –How does it compare with other scenarios?

Strategies and short lists Preferred scenarios are used to define development strategies –identify priority projects consistent with strategies Trade-offs may be required between different goals –eg economic development and environmental protection –scenario analysis helps define what is gained and what is lost Final decisions made by national governments

Formulating scenarios Use scenarios to test bounds of system, answer questions like –What will be the impact of dams in Yunnan on ecosystems of the LMB? Will they have a significant impact on Tonle Sap fisheries? availability of water for irrigation? flood frequency? –If population keeps growing at the current rate, will there be sufficient water to meet irrigation demands in 20 years? Use scenarios to examine impacts of specific development options –possible to analyse individual interventions, but DSF is built for regional scale assessments (not local)

Some example scenarios 1Nominal baseline 2Climate change 3Catchment cover change 4High irrigation growth 5Impact of China dams 6Impact of LMB dams 7Impact of flood embankments ………… 67Expansion of irrigation in eastern Cambodia 68 Kok-Ing-Nam diversion 69Impact on saline intrusion of changing farming systems in Delta 70Hydropower development in Central Laos