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Detecting Changes in River Flow Caused by Wildfires, Storms, Urbanization, Regulation, and Climate Across Sweden
Author(s) -
Arheimer Berit,
Lindström Göran
Publication year - 2019
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2019wr024759
Subject(s) - streamflow , environmental science , hydropower , land cover , climate change , storm , hydrology (agriculture) , urbanization , flow (mathematics) , climatology , land use , drainage basin , geography , meteorology , geology , ecology , oceanography , geometry , cartography , geotechnical engineering , mathematics , biology
Changes in river flow may appear from shifts in land cover, constructions in the river channel, and climatic change, but currently there is a lack of understanding of the relative importance of these drivers. Therefore, we collected gauged river flow time series from 1961 to 2018 from across Sweden for 34 disturbed catchments to quantify how the various types of disturbances have affected river flow. We used trend analysis and the differences in observations versus hydrological modeling to explore the effects on river flow from (1) land cover changes from wildfires, storms, and urbanization; (2) dam constructions with regulations for hydropower production; and (3) climate‐change impact in otherwise undisturbed catchments. A mini model ensemble, consisting of three versions of the S‐HYPE model, was used, and the three models gave similar results. We searched for changes in annual and daily stream flow, seasonal flow regime, and flow duration curves. The results show that regulation of river flow has the largest impact, reducing spring floods with up to 100% and increasing winter flow by several orders of magnitude, with substantial effects transmitted far downstream. Climate changed the total river flow up to 20%. Tree removal by wildfires and storms has minor impacts at medium and large scales. Urbanization, on the contrary, showed a 20% increase in high flows also at medium scales. This study emphasizes the benefits of combining observed time series with numerical modeling to exclude the effect of varying weather conditions, when quantifying the effects of various drivers on long‐term streamflow shifts.