Uwarunkowania i zmienność niżówek rzecznych w wybranych regionach geograficznych Polski w latach 1989–2018
Determinants and variability of river low-flows in selected geographical regions of Poland in the period 1989–2018

Summary/Abstract: The aim of the study was an identification and variability assessment of river low-flows in five big catchmentsin Poland that, due to their size and location, reflect the predominant features of the physico-geographical regions in whichthey lie. There were 92 gauging cross-sections with daily discharge series selected in the period 1989–2018. The data weretaken from the database of Polish Institute of Meteorology and Water Management – National Research Institute. Low-flowswere identified on the base of the Threshold Level Method where truncation discharge corresponded to the 70th percentileon the Flow Duration Curve. During analysis, multiannual and seasonal variability of low-flow duration, streamflow deficitand their derived characteristics were assessed. The research showed the relationship of precipitation distribution and waterbalance structure with average low-flow duration and the number of identified episodes. Specific features of catchments deter-mining low flows development were indicated. They resulted primarily from features of the catchment hydrogeologicaland hydrographic structure, land cover and evapotranspiration intensity. Attention was paid to shaping seasonal featuresof low-flows both in terms of their origin and the dynamics of development. The main anthropogenic factors have been iden-tified which affect the course of low-flows.

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