How do contaminated reservoir bottom sediments affect water quality? An assessment using SWIM model

Abstract

In this study, an approach for the assessment of long term effects of contaminated sediments on the surface water quality of a future reservoir is presented. A one-dimensional sediment-water interaction model designed to simulate contaminants associated with the sediments, and the transfer of these contaminants to the overlying water column, was developed. The effect of contaminated bottom sediments on water quality was investigated under different stratification conditions. The numerical model was applied to an existing reservoir (Tahtali Reservoir) for validation and projected contaminant concentrations based on the soil and water samples collected before inundation of the land. Results were compared with the concentrations obtained from water samples collected during its operation. Next, transfer to a planned reservoir (Çamli Basin, Izmir) of four heavy metals - copper, zinc, chromium, and lead - existing in bottom sediments of the planned reservoir is modeled. A ten year projection of heavy metal concentrations for the Çamli Reservoir showed concentrations to be higher than those acceptable by the World Health Organization (WHO). Construction of a treatment facility is recommended if the reservoir is to be utilized for providing domestic water.