Qualitative Behavior Identification of Surface Reservoir in Case of Sudden Injection of Contaminant Load

Sudden contaminant load in water resources either man made or in circumstantial process causes crisis. Appearance of MTBE contaminant load in Geshlagh Dam in Sanandaj city, entering the sudden contaminant load of oil determinatives into Zayandehrood River and Karkhe River are examples of such crisis that have occurred in Iran. The purpose of this study is evaluating and simulation of reservoir quality behavior in case of sudden contaminant load. This can help the managers and planners in selecting the applicable policies in the situation of quality crisis. In this paper, Karaj Dam reservoir simulation model has been created by the third version of two-dimensional mean transverse (CE-QUAL-W2) and a biological contaminant with coliform index has been considered as a sudden contaminant load. By considering the factors affecting the behavior of advection, dispersion, diffusion, and deterioration of coliform, five different scenarios have been created for 12 months of the studied year. These included coliform deterioration rate, the effect of reservoir water storage volume, contaminant load input location, the effect of water temperature, discharge into the reservoir, and the coliform sediment rate. Based on the defined scenarios, the rate of influences of each abovementioned factor on the behavior of pollutant has been investigated. The result shows that the input location of the contaminant load has a severe effect on the maximum output contaminant and crisis period. Therefore entering the contaminant load at the lower third of reservoir comparing to those of at the upper third of the reservoir has 15 times more output contaminant and the crisis period due to entering the contaminant load at the lower one third of the reservoir is two times of the crisis period due to entering the contaminant load at the upper one third of the reservoir.