THE IMPACT OF STORM WATER AND SEWAGE WATER ON THE QUALITY OF THE DNIPRO-RIVER WITHIN THE AREA OF KHERSON URBOSYSTEM

Abstract

Intensive development of urbanization contributes to deterioration in the quality of water resources. Discharge of urban polluted storm water and sewage water causing disruption of ecological balance and self-cleansing potential of hydro- ecosystems is especially dangerous.We established a regular sequence of dependent processes of the impact of the factors on the water environment as inputand output parameters of the urban system. We found out that the chemical composition of precipitation forming the surface outflow towards the water flows of Kherson due to the sloping relief is a major threat for the Dnipro-river. Partial functioningof the system of sewage outflow along the Dnipro slope because of its sediment pollution and its removal from the system of the municipal economy of the town results in discharging untreated sewage water into the Dnipro river.We determined spatially and seasonally dependent characteristics of the outflows from different landscapes of Kherson territory depending on the character and the total amount of the area with hard impervious surface, the surface slope, one- time amount of precipitation, the specificity of the town buildings and the level of transport loadings of the territory.The main components of the sewage are dry remains, their content being 30 g/l (the threshold limit value (TLV) is 1 g/l), formed by mineral compounds, salts, soil and sand components and biogenic-detritus particles. The degree of treatment by the dry remains, the content of sulphates and chlorides was 95%, caused by small volumes of sewage water, the lack ofpowerful industrial and transport environmentally hazardous objects. The analysis of the average annual levels of the hydro- chemical composition of the river water by the main indexes allowed determining an excess of the TLV by mineralization (1.50 TLV), chlorides (1.,24 TLV) and phosphates (4.26 TLV).The ecological condition and the functioning of the Dnipro river are caused by natural hydrological processes of partial self- cleansing and self-regulation of the water in the lake and overflow land ecosystems. In order to improve the quality of the Dnieper surface water we recommend nature conservation methods with respect to the organization of managing the system of the removal of storm water and urban sewage water and their reuse for irrigating agricultural crops provided that they are previously treated.