ASSESSMENT SCHEME OF WATER-RESERVOIRS IMPACT ON GROUNDWATER

Water reservoirs play a unique role in determining the mechanism of their impact on groundwater. The goal of our study was to develop a modern option of an impact mechanism and indicator scheme to assess reservoirs' impact on groundwaters. For this purpose, the methods of mathematical statistics and stochastic hydrology were used. Different types of reservoirs with different durations of exploitation were selected as study objects. As per the updated impact mechanism, the filtration regime and yield are the function of properties of water-reservoir level and the bed constituent rocks and respond to the level fluctuation with a certain delay. One of the main determinants of the delay time is the distance from the reservoir to the filtrate monitoring station. It was found that filtration decreases in proportion to the bed silting, while the time of delay increases in proportion to silting. As silting reaches its maximum, the filtration regime is determined only by the filtrate of the derivation tunnel and other structures and by the level of the reservoir. The indicator scheme selected to evaluate the reservoir impact on the groundwater is as follows: debit of streams, range of underground waters' horizon fluctuation, infrastructure affected by the landslide, and bogged plots of field. The criteria to assess the efficiency of the water reservoir are: if the filtrate is used for any purpose, its value augments the efficiency of the reservoir; if the filtrate is harmful to the infrastructure and environment, it undermines the importance of the reservoir.