A new optimized model to control eutrophication in multi-purpose reservoirs

Abstract

The entry of excess nutrients into the reservoir causes problems such as eutrophication, and as a result, we see a decline in the quality of water in the reservoirs and changes in the downstream ecosystem. In this study, a simulation–optimization model has been developed in the framework of selective withdrawal methods to achieve optimal operation policies that can meet the different objectives of the reservoir. A two-dimensional model called CE-QUAL-W2 was used to simulate the reservoir water quality processes. Also, the non-dominated sorting genetic algorithm (NSGA-II) was used as an optimization algorithm in the developed simulation–optimization model. The results show that the dissolved oxygen concentration of the outlet from the lower gate Seimare reservoir for the optimal operation policy is about 30% better than the current operating conditions. In addition, hydropower energy has increased by about 50%. The eutrophication status in the reservoir improved in relation to the existing condition, in most months of the year; the reservoir is in low eutrophication state for optimal operation policy. The results showed the high efficiency of this method and the considerable improvement of the various objectives of the reservoir.