Water quality modelling to support the operation of the Kakhovka Reservoir, Dnieper River, Ukraine

The model system that comprised 1D, 2D and 3D water quality models was developed and implemented for the main water bodies of the Kakhovka Reservoir and Lower Dnieper to evaluate the environmental effect of various reservoir operation and water management scenarios and also to analyse consequences of the accidental pollution of the reservoir. These models have been tested using the monitoring data for 1984-1988 and 1998. It was shown that the significant factor for the Kakhovka Reservoir is the rate of the nutrient sources from the cities around the reservoir and nutrients flux into the reservoir from the up- stream reservoirs rather than from Dnieper inflow discharge. The simulation of the water quality of lower Dnieper and Dnieper-Boog Estuary shows that the distance of the intrusion of the salt wedge into lower Dnieper linearly depends from the discharges from Kakhovka HPP for the discharges in range 600-4000 m 3 s -1 .