Zmiany w strukturze odpływu wody ze zlewni karpackich w półroczu hydrologicznym zimowym w latach 1981‑2020 = Changes in water-runoff patterns in Carpathian catchments during the winter hydrological half-years of the 1981-2020 period

Abstract

The main objective of the study was to spatially and temporally determine the structure of channel outflow and the directions of its changes in selected river catchments in the Western Carpathians during the winter hydrological semester, under conditions of climate change and increasing anthropopressure. The study included four drainage basins, representing features of the Beskids Mountain (Soła and Osława catchemnts) and Foothills Mountain (Skawinka and Stobnica catchments). The study cover period 1981-2020. The average outflow of the winter half-year (HWHY) ranged from 150.3 mm (Skawinka) to 348.8 mm (Oslawa), while the share of HWHY in the annual outflow (HA) averaged from 50.9% (Soła) to 60.4% (Stobnica). From 1981 to 2020, HWHY did not show statistically significant directions of change. Negative HWHY trends were found in all the studied catchments since 2000. In the studied catchments, there was a diversity of dominant sources of watercourse supply in HWHY. There was a recession of snowmelt-induced runoff ranging from 0.3 mm yr-1 (Skawinka) to 1.2 mm yr-1 (Soła) and an increase in the role of ground supply of 0.17 mm yr-1 (Skawinka) to 1.04 mm year-1 (Osława). The  runoff coefficient for WHY had lower average values in the foothill catchments: Stobnica (64%) and Skawinka (67%).