Flood Wave Dynamics in the Transboundary Dniester River Floodplain under Reservoirs Impact

Abstract

The present research aims to evaluate the impact of stream reservoirs on the Dniester river floods wave dynamics. The main approach consisted in the evaluation of the changes that occur in the flood parameters for three periods: natural flow, flow regulated by Dubasary reservoir, flow regulated by the Dniester hydropower complex and Dubasary reservoir. Using the hydrological time series from the stations situated upstream and downstream of the reservoirs, the following were calculated and compared: flood characteristics, peaks of 10, 5, 1, 0.5, and 0.1% probability, and environment flow components such as high-flow pulses, small floods, large floods. The results show that high flood protection is specific to the Dniester hydropower complex, while through the Dubasary reservoir the flood wave passes mainly in transit. Due to the flow regulating impact, small floods as well as their average peaks and duration were reduced toward the reservoirs’ downstream part. High-flow pulses increased in number after the Dniester hydropower complex construction due to hydropeaking effect; however, their reduction is observed downstream of the Dubasary reservoir. Large floods increase in number in the upper part but are transformed into small floods toward the downstream, thus increasing the flood protection capacity.

Keywords

• the Dniester river
• floods
• reservoirs impact
• environment flow components