GEOECOLOGICAL STATE OF THE FLOODPLAIN AND CHANNEL COMPLEX OF THE POLTVA RIVER BASIN (VISTULA RIVER BASIN REGION)

In accordance with the water management zoning of the territory of Ukraine, the Poltva river basin belongs to the Vistula river basin region. The evaluation methodology of the channel and floodplain river complex state was proposed by Himko R. V. (2005). According to this methodology, the parameters (23 indicators), characterizing river state by points scale (5 quality classes), were defined. The research included three steps. During the preparatory stage cartographic materials were investigated and the coastal protection zones were highlighted. The fieldwork stage included: visual assessment of water quality and of the state of channels; identification of sources of pollution and clogging of waters and coastal areas; study of features of anthropogenic load within floodplains. In the third stage, generalization and evaluation works were carried out. Wastewater discharges from enterprises and coastal settlements affect the water quality of the study area. Lviv has the greatest economic impact on the Poltva river due to its channelling within the city and due to large volumes of wastewater discharges (121.4 million m3 in 2017). The water quality of the Poltva River tributaries depends on sewage discharges from small industrial and public utilities, as well as on unauthorized sewage discharges in villages. Significant parts of the river channels are regulated. Drainage systems, that occupy much of the study area, as well as ponds and small reservoirs, directly affect on the hydrological regime of the rivers. The level of land-use of coastal territories is characterized by their urbanization level and their level of plowing. The urbanization of the upper reaches of the Poltva river valley is a determining factor that has influenced the sanitary status of its channel. Outside the Lviv city, many coastal areas (within the coastal protection zones) are plowed. Overgrowing of waters and obstruction of channels by water and coastal plant remains lead to a significant deterioration of sanitary conditions of the rivers, hence to secondary contamination of its waters. Geoecological state of the Poltva river channel and floodplain complex was designated as «unsatisfactory» (4th grade from 5 classes), of Yarychivka and Gologirka river complexes – as «satisfactory» (3rd grade), of other rivers – as «rather good» (2nd grade). The rivers of the Poltva watershed are under significant economic influence. To improve the geoecological state of river channels and floodplains, a complex of water protection measures is required: reduction of insufficiently treated wastewater discharges of Lviv city; cleaning of watercourses; monitoring of compliance with water protection rules etc.