Multi-annual and Seasonal Variability of Low-flow River Conditions in Southeastern Poland

Raczynski, K., & Dyer, J. (2020). Multi-annual and Seasonal Variability of Low-flow River Conditions in Southeastern Poland. Hydrological Sciences Journal. 65, 2561-2576. DOI:10.1080/02626667.2020.1826491.

The objective of this study is to quantify the seasonal and multi-annual variability and trends of low-flow river conditions in southeastern Poland. The study was performed using daily values of river discharge at 29 gauging stations for hydrological years 1976–2014. The results show regionally specific patterns, such that seasonality is high for the lowland rivers (low flows occur during the warm season), while in the upland rivers a 10- to 15-year cycle is observed. Increasing trends in warm-season temperature and a decrease in humidity were observed; however, no direct correlation with low flows was found. These results suggest that the initiation and maintenance of low-flow events over some regions are more sensitive to local surface water and groundwater circulation conditions than to atmospheric drivers, especially when the recurrence interval of events is low, and that the primary mechanisms driving and maintaining low-flow conditions can change over relatively small spatial scales.