Original scientific paper
Changes in Discharge Regimes of the Largest Sava and Drava Tributaries in Hrvatsko Zagorje and Gornja Podravina Regions (Northwestern Croatia) in 1961-2020 Period
Danijel Orešić
orcid.org/0000-0002-5809-085X
; Faculty of Science, University of Zagreb, Zagreb, Croatia
Anita Filipčić
orcid.org/0000-0003-1346-9898
; Faculty of Science, University of Zagreb, Zagreb, Croatia
Abstract
The largest tributaries of the Sava and the Drava rivers in the area of Hrvatsko zagorje region and Upper Podravina are the Krapina, the Sutla, the Bednja, and the Plitvica rivers. Given the availability of flow data from 1961-2020, the analysis of changes in flow regimes was conducted at three representative hydrological stations: Ludbreg on the Bednja River, Kupljenovo on the Krapina River, and Zelenjak on the Sutla River. The values of monthly averages and modular coefficients from two consecutive climatological standard thirty-year periods, 1961-1990 and 1991-2020, were compared. Changes in flow regimes were compared with changes in the annual pattern of monthly precipitation amounts, average monthly air temperatures, and the average number of days with snow cover at selected meteorological stations Varaždin, Stubičke Toplice, and Puntijarka. In the more recent period, there has been a decline in average monthly flows in almost all months, most significantly in the warm part of the year. The decrease in spring flows is influenced by rising air temperatures and a significant reduction in spring precipitation, especially snow. The summer flow decline is mainly influenced by the statistically significant increase in average monthly air temperatures. The reduced role of snow and the increased role of rain in the transition from autumn to winter causes more direct runoff, making the December maximum more pronounced in the flow regimes of all analyzed stations.
Keywords
flow; flow regime; climate change; Krapina; Bednja; Sutla; hydrogeography; hydrology; climatology
Hrčak ID:
320079
URI
Publication date:
16.7.2024.
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