METHODOLOGICAL APPROACHES TO DETERMINING THE CALCULATED CHARACTERISTICS OF RIVER FLOW (ON THE EXAMPLE OF RIVERS IN TERNOPIL REGION)

Abstract

The article presents methodological approaches to determining calculated characteristics of river runoff using the example of rivers in the Ternopil region: Zolota Lypa, Koropets, Strypa, Seret, Nichlava, and Zbruch. A comprehensive analysis of long-term runoff variations and intra-annual water distribution was conducted based on hydrological observations for the period 1981–2020, which provides sufficient representativeness for statistical calculations. To identify long-term phases of water availability, differential integral curves were used, allowing the assessment of runoff cyclicity, identification of high- and low-water periods, as well as determination of the duration and amplitude of water level fluctuations. The study of monthly water discharges enabled the evaluation of seasonal features of the hydrological regime, identification of intra-annual maxima and minima of water flow, and characterization of spring flood peaks, summer–autumn low-flow periods, and stable winter runoff. It was established that for larger rivers (Seret, Zbruch), seasonal water fluctuations are more smoothed, while smaller rivers (Zolota Lypa, Koropets, Nichlava) are characterized by more pronounced and contrasting runoff changes. The integrated approach, combining annual, monthly, and integral methodologies, allows a holistic understanding of river runoff structure, assessment of flood and low-water risk, and consideration of the spatial and hydrographic characteristics of river basins. The results emphasize the importance of adapting methods for determining calculated characteristics of river runoff to contemporary hydroclimatic conditions, which is particularly relevant under climate change and anthropogenic influence. The findings have practical significance for water management planning, hydrological event forecasting, and management of water resources in medium and small rivers under the complex natural and climatic conditions of the Ternopil region.