1. MEKONG RIVER COMMISSION RIVER BASIN PLANNING - MODULE 1 INTRODUCTION Can Tho, Vietnam 20 - 23 January 2003 The Art of Scenario Evaluation

2. What Can A Basin Model Do for BDP? BASIN PLANNING - SCENARIO EVALUATION What Can A Basin Model Do for BDP? The MRC models simulate changes in river hydrology and floodplain inundation that are the result of: –changes in demand (ie water extractions); and –building & operating dams or other river structures. Traps for the unwary: The models only replicate the period of hydrological record. Is this truly representative? Models often produce results that some interest group does not believe. How to resolve this? The models do not help much with many decisions. MRC will need to become skilled at making decisions with limited information.

3. What do Planners Need to Tell Modellers? BASIN PLANNING - SCENARIO EVALUATION What do Planners Need to Tell Modellers? Location of each proposed development. Hydrological parameters of the development: –reservoir capacity; –discharge capacity; –water demands (daily / monthly); –minimum flow rules; etc. Places on the river where outputs are needed: –junctions of critical tributaries; –national boundaries; etc. Preferred form of outputs: –raw data; –monthly maxima, minima, and/or averages; –flow-duration curves; etc.

4. How Can Scenario Outcomes be Assessed? BASIN PLANNING - SCENARIO EVALUATION How Can Scenario Outcomes be Assessed? Not easily! BENEFITS (the primary reason for the project) The simulation models available only generate water outputs (flow, depth etc). Therefore a simple set of socio-economic outcomes needs to be separately calculated. EFECTS ON THE MEKONG RIVER Simulated by the models. (quantified changes to the river hydrology and to flood patterns ) BUT - the models do not directly compute: environmental effects, water-sharing trade-offs, etc

5. Indirectly Computed Scenario Outcomes BASIN PLANNING - SCENARIO EVALUATION Indirectly Computed Scenario Outcomes Environment, geomorphology, health, navigation and other interests need to talk to the modellers to find some useful, substitute hydrological indicators that could be generated - eg for fish breeding, the models could produce: –changes in flow patterns; –changes in frequency of floodplain inundation; etc For those scenario outcomes that are of interest but not easily quantified, such as recreation and tourism, qualitative descriptions will need to be produced. (Mostly, these can be broadly predicted by knowledgeable experts)

6. The Need for Assessment Criteria BASIN PLANNING - SCENARIO EVALUATION The Need for Assessment Criteria The two key BDP questions: –Which development proposals are acceptable and which are unacceptable? –Which acceptable proposals are “better” than other acceptable proposals? can only be answered when outcomes are tested against basin objectives. A set of assessment criteria will be used to evaluate the extent to which each scenario is successful in achieving the objectives of the Mekong Agreement

7. Development of Assessment Criteria BASIN PLANNING - SCENARIO EVALUATION Development of Assessment Criteria

8. Assessment Criteria BASIN PLANNING - SCENARIO EVALUATION Assessment Criteria Some criteria are already in the Agreement (for example Art 6 and Art 26) Quantifiable criteria are to be preferred. Environmental criteria will need hydrological substitutes wherever possible. Criteria must be “owned” by stakeholders. Therefore it is expected that developing a suite of acceptable assessment criteria will be a lengthy process with significant consultation within the “internal stakeholders” or “MRC family”.

9. Assessment Criteria BASIN PLANNING - SCENARIO EVALUATION Assessment Criteria A key reason for this being a lengthy process and for it needing “ownership” by stakeholders is that the criteria can be thought of not as: –a means of testing which development is possible, but as –a means of protecting the values or “assets” that the people of the Mekong wish to preserve. In other words the assessment criteria, in effect, define the limits to development.

10. Assessment Criteria Key Principle BASIN PLANNING - SCENARIO EVALUATION Assessment Criteria Key Principle Criteria should be limited to those that are both necessary and sufficient to: Ensure the objectives of the Mekong Agreement and the Mission of the MRC are progressed; and to Enable the relative merits of scenarios (and thus specific development options) to be adequately differentiated.

11. Basin Planning is not Project Planning BASIN PLANNING - SCENARIO EVALUATION Basin Planning is not Project Planning Scenario assessment criteria are not those that may later be used (either by riparians or MRC acting together) to select specific development that will actually be commissioned. Before any development can actually start (even though it ranks highly against the assessment criteria) it will be necessary to build a detailed business case for the development. Preparation of such a business case is external to the Basin Development Plan.

12. Comparing Scenarios BASIN PLANNING - SCENARIO EVALUATION Comparing Scenarios Quantified model outputs applicable to each assessment criterion can simply be compared (and ranked) numerically. Non-quantified results of each scenario can be ranked subjectively against each assessment criterion by knowledgable people. However, because scenarios will have a mix of rankings against various criteria, a variety of multi-criteria analysis tools will be required.

13. The Need for Multi-Criteria Analysis Which Scenario is Best? BASIN PLANNING - SCENARIO EVALUATION The Need for Multi-Criteria Analysis Which Scenario is Best? * Subjective, non-numerical ratings

14. Multi-Criteria Analysis (MCA) BASIN PLANNING - SCENARIO EVALUATION Multi-Criteria Analysis (MCA) MCA is not always as useful as some enthusiasts might claim. Nonetheless, the nature of the criteria will mean that selection of a methodology that works in the Mekong context will be necessary. Experience shows that this can be a time- consuming exercise. Advice: Keep it simple.

15. Trade-offs BASIN PLANNING - SCENARIO EVALUATION Trade-offs Water resource planning always involves “trade- offs” - giving up something to gain something else. In multi-country basins, the win and the loss may occur in different countries The challenge for basin planners is to find complementary off-setting deals that may appeal to the decision-makers (governments). The objective is to find basin-wide development strategies that are superior to the sum of independent national strategies.

16. Trade-offs BASIN PLANNING - SCENARIO EVALUATION Trade-offs Water is finite! (Dublin Principle No 1) This means that : Every extraction of water changes the downstream flow (which in turn alters the conditions downstream); and There is an opportunity cost. (This water cannot be used anywhere else). Modelling and scenario evaluation is needed to determine whether these trade-offs are acceptable.

17. Decision Making under Uncertainty BASIN PLANNING - SCENARIO EVALUATION Decision Making under Uncertainty Basin Planning Rule #1 - There is NEVER enough information for a guaranteed, perfect decision. Basin Planning Rule #2 - Development pressures are sufficiently strong that decisions will be made with or without a Plan. Conclusion: An interim Plan, with its decisions made under a state of uncertainty is better than no Plan. Although game theory and so on are worth knowing about, the MDBC experience is that participatory decisions involving all stakeholders, who are given whatever information is available are surprisingly good decisions.