Climate-driven changes to streamflow patterns in a groundwater-dominated catchment

Abstract

This study aims to investigate trends and regime changes in streamflow and basic factors driving these changes. The investigated area is located in central Poland and is influenced by temperate transitional climate. New insight is provided into the phenomenon of past climatedriven changes to streamflow patterns over a 65-year period (1951-2015). The Mann-Kendall test for monotonic trends and the CUSUM test are used to determine the presence or absence of changes in climatic variables, shallow groundwater level, and streamflow. Time series are explored to detect the direction of trends and the period when the significant change occurred. Differences in climatic conditions and streamflow patterns are discussed for two sub-periods, before and after the change. Overall, the results suggest stability in precipitation, with limited evidence for change in the annual amount, but reveal a significant change in streamflow regime in the 1980s, attributed to higher temperature driving evapotranspiration and reducing shallow groundwater recharge. It is concluded that the catchment is prone to increased evapotranspiration and in effect to greatly reduced runoff. Keywords Streamflow regime Á Climatic changes Á Groundwater-dominated catchment Á Central Poland

Trend detection in river flow indices in Poland

“…Dominating downward trends in river flow indices detected in this study for rivers situated on the Polish plain are supported by publications of other authors (Banasik et al 2013;Somorowska 2017). Upward trends in mean winter and spring season flows found in this study for numerous stations located in the southern part of Poland were also found by Kędra (2017) for the River Soła located in the Carpathians.…”

“…More recent studies usually focused on single catchments (e.g. Banasik et al 2013;Ilnicki et al 2014;Kędra 2017;Miler 2015;Somorowska 2017) or small regions (Niedźwiedź et al 2015;Ruiz-Villanueva et al 2016;Sen and Niedzielski 2010), with one notable exception of Wrzesiński and Sobkowiak (2018) who analysed long-term changes (but not trends) in flow regime of 159 flow gauges with a good geographical coverage in Poland. Polish rivers were not included in several pan-European (Hannaford et al 2013;Stahl et al 2010) or global (Hodgkins et al 2017) studies on trend detection, perhaps due to restrictive data sharing policy .…”

G2DC-PL+ A gridded 2 km daily climate dataset for the union of the Polish territory and the Vistula and Odra basins

“…(3) a streamflow trend detection study (Somorowska, 2017), (4) a hydro-ecological classification (Piniewski, 2017), and 5ecological modelling (O'Keeffe et al, 2018). Furthermore, the same methodological workflow as in (Berezowski et al, 2016) was used to prepare hydrological model forcing in (Berezowski et al, 2019).…”

The impacts of changes in climate and land use on hydrological processes

“…The papers published under this Topical Issue can be classified into those describing observed changes in flow patterns in catchments (Kundzewicz et al 2017b;Somorowska 2017), papers presenting changes in the trends of future flow projections Piniewski et al 2017). The paper by Doroszkiewicz and Romanowicz (2017) presents issues related to adaptation to floods under future climatic conditions.…”

“…There are two papers in this issue that directly deal with the observed flow patterns (those by Somorowska 2017; Kundzewicz et al 2017b). Somorowska (2017) describes the trends in flow regime in a low-land catchment, Lasica. The 65-year long flow and groundwater level records were analysed.…”