Skok S. Characteristics of sewage-surface drains of Kherson and evaluation of their impact on the state of hydroecosystems of the Lower Dnieper

The thesis provides the hydrological and hydrochemical research of sources of water supply, distribution of sewage-surface drains in the urbosystem, evaluation of their influence on the state of hydroecosystems of the Lower Dnieper using cartographic methods and mathematical statistics. About 70 % of the drain network of Kherson is in a state of soil-mud pollution, 60 % of the sewage system has an unsatisfactory technical condition, which leads to its systematic breakthroughs, leakage and redistribution of sewage effluents in the groundwater. The hydrochemical properties of uncleaned and weakly purified sewage-surface discharges in the Dnieper river basin, according to some indicators, exceed the value of the BPC for the needs of the fishery: sewage drains in 1,2-4,2 times, surface drains in 1,12–163,8 times. Influence of surface drains of the Kherson urbosystem on the hydroecosystem of the Dnieper river on the 100- and 300-meter zone of the river water area determines the relation of the river water to the class for fishery purposes: in 100-meter zone “very dirty” – “extremely dirty”; in the 300-meter zone “dirty” – “very dirty”. This causes the unsatisfactory ecological state of the hydroecosystem of the Lower Dnieper in zone of the influence of the urbosystem and beyond its boundaries in the direction of the water flow.