Groundwater shapes North American river floods

<p>The importance of soil moisture in triggering river floods is increasingly recognized. However, soil moisture represents only a fraction of the water stored in the unsaturated zone. In contrast, groundwater from the deeper, saturated zone, may contribute a significant proportion of river fl...

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Main Authors: Berghuijs, WR, Slater, LJ
Format: Journal article
Language:English
Published: IOP Publishing 2023
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author Berghuijs, WR
Slater, LJ
author_facet Berghuijs, WR
Slater, LJ
author_sort Berghuijs, WR
collection OXFORD
description <p>The importance of soil moisture in triggering river floods is increasingly recognized. However, soil moisture represents only a fraction of the water stored in the unsaturated zone. In contrast, groundwater from the deeper, saturated zone, may contribute a significant proportion of river flow, but its effects on flooding are poorly understood. Here we analyze hydroclimatic records of thousands of North American watersheds spanning 1981–2018 to show that baseflow (i.e. groundwater-sustained river flows) affects the magnitude of annual flooding at time scales from days to decades. Annual floods almost always arise through the co-occurrence of high precipitation (rainfall + snowmelt) and baseflow. Flood magnitudes are often more strongly related to variations in antecedent baseflow than antecedent soil moisture and short-term (⩽3-day) extreme precipitation. In addition, multi-decadal trends in flood magnitude and decadal flood variations tend to better align with groundwater storage and baseflow trends than with changing precipitation extremes and soil moisture. This reveals the importance of groundwater in shaping North American river floods and often decouples the spatial patterns of flood trends from those of shifting precipitation extremes and soil moisture.</p>
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spelling oxford-uuid:9bd7894e-de88-44fd-99bd-4af7f87403ec2023-06-19T09:04:00ZGroundwater shapes North American river floodsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:9bd7894e-de88-44fd-99bd-4af7f87403ecEnglishSymplectic ElementsIOP Publishing2023Berghuijs, WRSlater, LJ<p>The importance of soil moisture in triggering river floods is increasingly recognized. However, soil moisture represents only a fraction of the water stored in the unsaturated zone. In contrast, groundwater from the deeper, saturated zone, may contribute a significant proportion of river flow, but its effects on flooding are poorly understood. Here we analyze hydroclimatic records of thousands of North American watersheds spanning 1981–2018 to show that baseflow (i.e. groundwater-sustained river flows) affects the magnitude of annual flooding at time scales from days to decades. Annual floods almost always arise through the co-occurrence of high precipitation (rainfall + snowmelt) and baseflow. Flood magnitudes are often more strongly related to variations in antecedent baseflow than antecedent soil moisture and short-term (⩽3-day) extreme precipitation. In addition, multi-decadal trends in flood magnitude and decadal flood variations tend to better align with groundwater storage and baseflow trends than with changing precipitation extremes and soil moisture. This reveals the importance of groundwater in shaping North American river floods and often decouples the spatial patterns of flood trends from those of shifting precipitation extremes and soil moisture.</p>
spellingShingle Berghuijs, WR
Slater, LJ
Groundwater shapes North American river floods
title Groundwater shapes North American river floods
title_full Groundwater shapes North American river floods
title_fullStr Groundwater shapes North American river floods
title_full_unstemmed Groundwater shapes North American river floods
title_short Groundwater shapes North American river floods
title_sort groundwater shapes north american river floods
work_keys_str_mv AT berghuijswr groundwatershapesnorthamericanriverfloods
AT slaterlj groundwatershapesnorthamericanriverfloods