Long term hydrological and environmental monitoring of the Stryi River using remote sensing data and GIS technologies

Abstract

The proposed research sets the task of conducting monitoring aimed at determining the horizontal displacements of the channel of the Stryi River the largest right-bank tributary of the Dniester River. For this purpose, the river was zoned according to morphometric and hydrological characteristics. Three parts were identified, namely highland, piedmont and lowland ones, which radically vary in the nature of the flow and the amount of the displacement. The main research purpose consists in analyzing the impact of anthropogenic factors on the hydrological regime of the Stryi River, as well as studying the effect of the Ukrainian Carpathian Foredeep (UCF) and the Stryi Deep on the mode of horizontal displacements. The research object is processes occurring within the Stryi River channel. Considering main natural factors affecting the channel’s horizontal displacements, special attention is paid to the geological and sedimentological structures located in the region where the Stryi River and its tributaries flow; among the anthropogenic factors, deforestation and the extraction of building materials from the river channel are highlighted. Topographic, geological, soil maps and satellite images of various periods uploaded into ArcGIS software allowed us to monitor displacements observed for as long as 140 years ago. To monitoring the Stryi River channel displacements, such materials as topographic maps scaled 1: 75000 (Austrian period – 1874), 1: 100000 (Polish period – 1933, Soviet period – 1990); satellite images of Sentinel-2 (2019 and 2020 (after the flood)); a map of Quaternary sediments and a soil map scaled 1: 200000 were used. The Stryi River flows between two structures, i.e. the Skybovi Carpathians and the UCF. The right-bank tributaries (Bystrytsia, Limnitsia, Stryi, etc.), which begin in the Carpathians, cross the outer and inner boundaries of the UCF and are characterized by the stable river channel in its mountainous part, multi-braided in its piedmont part, as well as perennial and significant meandering within the Pre-Carpathian region. Lithological deposits have a significant impact at the mouth of the Stryi River. According to the research study results, displacements of up to 1,350m are measured in this area. The research includes an analysis of the influence of geological and sedimentological structures on the Stryi River displacement and the nature of its flow. It has been established that deforestation in the river basin, as well as unauthorized extraction of gravel materials, creates a significant environmental problem in this region. The results of monitoring of the channel deformation processes should be taken into account when solving problems related to river channel processes, namely the construction of hydraulic structures, the design of power transmission networks crossing rivers, the development of gas pipelines, the identification of hazardous flooding zones, the determination of consequences of destruction after floods, the establishment of boundaries of water protection zones, the management of recreational activities, monitoring of border lands and the establishment of an interstate border along rivers.