Application of a GIS-based simulation tool to illustrate implications of uncertainties for water management in the Amudarya river delta

River basin management decisions have to be made under uncertainty. Relevant uncertainties especially in external driving forces can often not be sufficiently reduced. Rather than expecting to eliminate them, new management strategies should thus aim at taking them into account. Simulation tools can support a process of reasoning about the implications of uncertainties for the outcome of management policies in a specific river basin management context. Model supported scenario analysis of alternative strategies with authorities, managers and other stakeholders can assist in the development of new strategies. The tools provide factual knowledge on the outcome of policy options proposed as scenarios by the participants to the debate. The GIS-based simulation tool TUGAI has been developed to support assessment of the ecological effects of alternative water management strategies in the degraded Amudarya river delta. It combines a multi-objective water allocation model with simple models of landscape dynamics and a fuzzy based evaluation of habitat suitability for riverine Tugai forests. In this paper an example application of the tool for scenario analysis to illustrate the implications of uncertainty in future water supply to the delta area is demonstrated. Scenario analysis provides an assessment of the range and magnitude of the impact of those uncertainties on the ecological situation in the delta. The potential and limitations of applying simple simulation tools in participative settings for analysis and discussion of the potential impacts of uncertainties and development of cooping strategies are discussed.