Investigation of Reservoir Qualitative Behavior Resulting from Sudden Entry of Biological Pollutant

Abstract

In this paper, fluctuation in reservoir water quality is simulated and evaluated upon the sudden entry of a biological load. By using Version 3.2 of the two-dimensional quality simulation software CE-QUAL-W2, Iran’s Karaj Reservoir is simulated, and a biological pollutant with coliform index is considered as the level of the pollutant. By considering factors involved in dispersion, advection, and decay of coliform, nine factors (nine sets of scenarios) are defined, and their influences on the pollution behavior are investigated. To investigate further, pollutant behavior is evaluated in various scenarios: water release, level of water withdrawals, input pollutant load volume, coliform decay rate, stored water volume in the reservoir, entry location of pollutant load, effect of water temperature on coliform decay, inflow to reservoir, and coliform sedimentation rate. Results show that some factors affect the pollutant behavior significantly, such as stored water volume in the reservoir and entry location of the pollutant load, so that the main changes in released pollution concentration appear with a decrease and increase of 25% in reservoir storage volume. Also, the closer the pollutant load entry location to the reservoir outlet, the higher the released pollution concentration. Maximum pollution released from the reservoir in the condition of entry of pollutant load in the lower third of the reservoir relative to the entry of pollutant load in the upper third is 15 times more.