Hodgkins, Glenn A. and Renard, Benjamin and Whitfield, Paul H. and Laaha, Gregor and Stahl, Kerstin and Hannaford, Jamie and Burn, Donald H. and Westra, Seth and Fleig, Anne K. and Araújo Lopes, Walszon Terllizzie and Murphy, Conor and Mediero, Luis and Hanel, Martin (2024) Climate Driven Trends in Historical Extreme Low Streamflows on Four Continents. Water Resources Research, 60 (6). ISSN 0043-1397

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Abstract

Understanding temporal trends in low streamflows is important for water management and ecosystems. This work focuses on trends in the occurrence rate of extreme low‐flow events (5‐ to 100‐yearreturn periods) for pooled groups of stations. We use data from 1,184 minimally altered catchments in Europe,North and South America, and Australia to discern historical climate‐driven trends in extreme low flows (1976–2015 and 1946–2015). The understanding of low streamflows is complicated by different hydrological regimes in cold, transitional, and warm regions. We use a novel classification to define low‐flow regimes using air temperature and monthly low‐flow frequency. Trends in the annual occurrence rate of extreme low‐flow events(proportion of pooled stations each year) were assessed for each regime. Most regimes on multiple continents did not have significant (p < 0.05) trends in the occurrence rate of extreme low streamflows from 1976 to 2015;however, occurrence rates for the cold‐season low‐flow regime in North America were found to be significantly decreasing for low return‐period events. In contrast, there were statistically significant increases for this period in warm regions of NA which were associated with the variation in the Pacific Decadal Oscillation. Significant decreases in extreme low‐flow occurrence rates were dominant from 1946 to 2015 in Europe and NA for both cold‐ and warm‐season low‐flow regimes; there were also some non‐significant trends. The difference in the results between the shorter (40‐year) and longer (70‐year) records and between low‐flow regimes highlights the complexities of low‐flow response to changing climatic conditions

Item Type:	Article
Additional Information:	We appreciate the assistance of individuals and agencies with obtaining the daily streamflow and metadata for the stations in this study. Reference hydrological networks (RHN): Bureau of Meteorology(Australia); Agencia National de Aguas(Brazil); Water Survey of Canada; Czech Hydrometeorological Institute (JanDaňhelka); French Banque HYDRO/Hydro Portail Archive (France); Irish Reference Network (Ireland); Norwegian Water Resources and Energy Directorate(Norway); Swiss Federal Office for the Environment (Switzerland); National River Flow Archive (UK); U.S. Geological Survey (United States). Stations with streamflow data with similar quality characteristics (RHN‐like): Agriculture,Forestry, Regions and Water Management(Austria); Finnish Environment Institute SYKE (Finland; Johanna Korhonen);Federal Institute of Hydrology (Germany);Centre of Hydrographic Studies of CEDEX and Anuario de Aforos of the Spanish Ministry of Environment (Spain).We also appreciate the contributions made during the development of this project byMark Thyer (University of Adelaide).Most importantly, we appreciate the efforts of all the hydrometric technicians and technologists who made the observations over many decades and produced the streamflow data used in this study. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S.Government. J. Hannaford was supported by the ROBIN (Reference Observatory of Basins for International hydrological climate change detection) initiative, with funding from the Natural Environment Research Council (grant number NE/W004038/1). B. Renard has received funding from the European Union's Horizon 2020 research and innovation program under the Marie‐Sklodowska‐Curie grant agreement No 835496. G.Laaha received funding from the Austrian Climate Research Program ACRP under the project DIRT (GZ C265154).
Keywords:	hydrological networks; water management; extreme low flows;
Academic Unit:	Faculty of Social Sciences > Geography Faculty of Social Sciences > Research Institutes > Irish Climate Analysis and Research Units, ICARUS
Item ID:	18700
Identification Number:	https://doi.org/10.1029/2022WR034326
Depositing User:	Corinne Voces
Date Deposited:	02 Jul 2024 15:47
Journal or Publication Title:	Water Resources Research
Publisher:	Advancing Earth and Space Sciences, AGU
Refereed:	Yes
URI:	https://agupubs.onlinelibrary.wiley.com/...
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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