using system dynamics approach to simulating eutrophication in artificial lakes

background: nowadays the eutrophication of water bodies is enhanced due to discharge of effluents and runoffs. therefore, there is a demand for the management of natural and artificial lakes to prevent or postpone this problem. lakes eutrophication is a complex process. therefore computerized models are very important tools to describe this process. although there are several models for this, but these are not suitable for managing and overall assessment of water resources. methods: in this study a processing model was constructed. first the euthrophication system, parameters and characteristics were defined on vensim. then mathematical equations of each process was determined and entered to the system. finally, the calibration and validation of the model was conducted by long lake reservoir data. findings: based on the findings of this model major euthrophication variables include phosphorus, nitrogen, phytoplankton and zooplankton could be stimulated. the findings of calibration and validation of the model is pointed that this model can simulate euthrophication with minimum data.  conclusion: it was indicated by the results that phosphorus is a limitation factor in reservoir. the unique properties of this model are its simplicity and minimum needs data.