Determining the accuracy of the dynamic system in simulating and optimizing the rule curves of the dam reservoir (Case Study: Choghakhor dam)

Increasing water demands and limited water resources in arid and semiarid regions have required management and planning to optimal use of the water resources. On the other hand, the surface water resources providing a major portion of water supply for drinking, agriculture and industrial sectors. For this porpuse, managers need to adopt optimal policies for planning water resources use, especially reservoirs of dams. Therefore, many attempts have been made to develop computer models to perform such simulations. One of the most effective methods to evaluate complex systems is system dynamics. This approach is a feedback-based and object-oriented approach. Any dynamic system is characterized by interdependence, mutual interaction, information feedback, and circular causality. However, Vensim is a visual modeling tool that allows you to conceptualize, simulate, analyze, and optimize models of dynamic systems. Vensim model provides a simple and flexible way of building simulation models from causal loop or stock and flow diagrams. So, in this research, system dynamics and particle swarm optimization algorithm were used to optimize the rule curve of Choghakhor Dam. Finally, the accuracy of the methods was evaluated. The study area is located near Borujen city. the Choghakhor dam is a earth fill dam and its water is mainly supplied through precipitation and springs. In this study, the results are compared with monthly data collected over ten years period (2004-2014) in the Choghakhor Dam. The relations between the inflow, the volume of reservoir storage and the rate of release of each period were determined and they were defined by using system dynamics approach in VENSIM model and using pso algorithm in MATLAB model. the objective function and all of the limitations are the same for both of the models. The results showed that The coefficient of determination (r2) which is a measure of the degree of correlation between the system dynamics simulation and the observation data was 0.995 for the reservoir volume and 0.991 for the release rate. After optimization the difference between the requirements and the release rates decreased and reduced the waste of water. The difference was 11.78 MCM for system dynamics approach and 18.82 MCM for PSO algorithm. While in observation, The difference was 25.68 MCM. In general, the results showed that the system dynamics model is more accurate than the pso algorithm in optimisation of the reservoir operation by rule curve adjust in Choghakhor dam.