عنوان مقاله [English]
Eutrophication is one of the main environmental problems in dam reservoirs which affect the availability of water with suitable quality. Effective management and control of such phenomenon in a reservoir may support by implementation of low-complexity simulation models employing the most effective water quality parameters and processes. System dynamics (SD) is one of object oriented simulation tools that is able to simulate the eutrophication process in a reservoir according to the systemic approach and with emphasis on the causal relationships and feedbacks. In this paper, a system dynamic simulation model for phosphorous concentration of the Satarkhan reservoir in Eastern Azerbayejan Province, North-western Iran, has been developed. In this model, the phosphorous has been considered as the main factor of eutrophication. Also the interaction between the phosphorous in the reservoir and the bed sediment has been considered with monthly variable coefficients of phosphorous burial in sediments. Sensitivity analysis were made on the coefficients and calibration and validation of the model have then been achieved based on a 47 month period of data. Results showed an acceptable reliability in simulation of phosphorus concentration despite the simple assumptions used. Fractions of the phosphorous in the input, output, sediments, and the reservoir showed the significance of sediments in phosphorus concentration equilibrium. Analysis of scenarios regarding the reduction and increase of input load to the reservoir also showed that the impact of phosphorous input load reduction is at a smaller extent effective which should be considered in nutrient load management in the watershed.