MODERN STATE OF THE WESTERN BUG RIVER BASIN WITHIN THE VOLYN REGION

Abstract

Problem Statement and Purpose. Anthropogenic loading on natural objects increases today, so that, studying changes in nature is especially important task of modern sci­ence. It should be noted, that hydrographic grids and separate water bodies are vulner­able to change in the environment. Consequently, it is quite necessary to investigate water bodies, considering account the natural and artificial factors of their formation. Such research allows us to determine the impact of human activity on the functioning and dynamics of aquatic natural landscapes. So that, the main purpose of the article is to study the peculiarities of functioning of the Western Bug river system within the Volyn region in the modern conditions.Data & Methods. The information base of the research includes the scientific works about hydrological and hydrochemical features of the Western Bug River and its tributaries, published by M. R. Zabokrytska V. K. Khilchevkyi A. P. Manchen­ko O. R. Perkhach F. Ya. Kiptach M. I. Syrotiuk. Furthermore, it was used works about nature in the Volyn region of K. I. Herenchuk Ya. O. Molchak T. S. Pavlov­ska F. V. Zuzuk etc. The actual statistical information for writing was taken from the Volyn Regional Center for Hydrometeorology. During our research it was used a number of general scientific and general geographical methods. The authors apply generalization, abstraction, analysis, synthesis, comparative-geographical and carto­graphic methods in the process of research. Furthermore, to investigate the level of rivers contamination, the method of determining the water pollution index was used. This index was calculated as the difference between the actual concentration of six main pollutants and their maximum allowable concentrations in the water. Modern ecological state of two largest rivers in the network (the Western Bug River and the Luga River) was determined according to the "Methods for ecological assessment of surface water quality by relevant categories".Results. The Western Bug River is one of the biggest rivers in the region. The river springs in the Lviv region, further falls into the Volyn region where moves along the border with The Republic of Poland, then enters the Republic of Belarus and again occurs in the Republic of Poland. In the Volyn region main river forms hydrographic grid in the western part of the exploring territory. The grid consists a lot of small rivers, streams and canals. The largest branch of the river system is the Luga River, which has four own tributaries. The Western Bug River and its branches carry out their water to the Polish main waterway – Vistula River.Furthermore, it is mentioned, that river valleys transform as a result of two main reasons: natural changes in the environment and anthropogenic activities. The article gives information about natural conditions of territory where the Western Bug River and its tributaries flow. The hydrographic grid of the Western Bug River elongates me­ridionally in the Volyn region and crosses two natural zones: zone of deciduous forests and zone of mixed coniferous forests, which change each other from south to north. The authors investigated that natural conditions in these two zones are quite different.For example, geological and geomorphological structures of two zones formed dif­ferences between river valleys of the Western Bug River and its tributaries, which change from south to north. The zone of deciduous forests formed on the Volyn High­land, while zone of mixed coniferous forests appeared on the Polesian Lowland. As a result, river valleys in the Volyn Highland are well expressed in the relief and have sleep slopes. As opposed to condition in south region, on the Polesian Lowland flood­plains widen, valleys lie at lower levels and rivers form many bends.Besides, climate has a particular important place in determination conditions of river formation and its dynamics. Each water body depends on the climatic features of the atmosphere. So that, it is noted, that basin of the Western Bug River is located in the mild climate with long spring and autumn and uneven distribution of precipitation during the year.The article provides that all these components of climate determine hydrological and hydro chemical properties of the river waters. Water level and water mineralization depend on amount of precipitation, source of feeding etc. Despite the fact that natural conditions are the basis for the development of the hydrographic grid and its features, the authors point to the major human activities, which transform these conditions. It is mentioned, that the most destructive measure, which was carried out by people was melioration works in the Polissya. This works led to irreversible changes in the ecosystems of the small rivers.The article considers the problem of the influence of different sources of pollution on the drainage basin of the Western Bug River. Furthermore, the authors give informa­tion about the sewage discharges to the hydrographic grid. The main sources of con­taminated wastewater are housing and communal services and enterprises. Besides, pollutants get into the Western Bug river system from enterprises of the Lviv region. Also the qualities of water in the main waterways of the hydrographic grid – the Western Bug River and the Luga River were investigated. It was defined that water pollution index of the Western Bug River and the Luga River is equal to second class (clean water). However, the content of some chemical substances in the water exceeds the maximum permissible concentrations. So that, according to the calculation of the generalized ecological index river waters belong to weakly polluted.The authors concluded that anthropogenic loading on the water bodies in the Volyn re­gion has been causing changes in their functioning and dynamics. The most negative consequences of human activity had melioration works, which transformed natural landscapes of the river valleys. The main modern pollutants of river waters are sew­age, which get into the water bodies from enterprises, utilities and agricultural fields. The ecological state of the Western Bug River and Luga River is classified as weakly polluted watercourses.