**1. Introduction**

Water resources management relies on the application of a systems approach to deal with complex problems [1]. This approach uses a systems analysis in finding solutions for complex water problems trying to balance between conflicting social, ecological and economic concerns that affect the decision-making process [2]. This study uses one of the two main techniques of systems analysis -simulation. In particular, the system dynamics simulation based on the causal, stock and flow diagraming is implemented. System dynamics simulation is an appropriate approach for the analyses of interconnecting processes and functional relationships of the water resource system components [3]. Using systems analysis, the water resources professionals are able to define plans, design and define reservoir operations for complex water systems under present and future climates.
