Print Email Facebook Twitter HESS Opinions Title HESS Opinions: Are soils overrated in hydrology? Author Gao, Hongkai (East China Normal University; Chinese Academy of Sciences) Fenicia, Fabrizio (Swiss Federal Institute of Aquatic Science and Technology) Savenije, Hubert (TU Delft Water Resources) Date 2023 Abstract Traditional hydrological theories are based on the assumption that soil is key in determining water's fate in the hydrological cycle. According to these theories, soil hydraulic properties determine water movement in both saturated and unsaturated zones, described by matrix flow formulas such as the Darcy–Richards equations. They also determine plant-available moisture and thereby control transpiration. Here we argue that these theories are founded on a wrong assumption. Instead, we advocate the reverse: the terrestrial ecosystem manipulates the soil to satisfy specific water management strategies, which are primarily controlled by the ecosystem's reaction to climatic drivers and by prescribed boundary conditions such as topography and lithology. According to this assumption, soil hydraulic properties are an effect rather than a cause of water movement. We further argue that the integrated hydrological behaviour of an ecosystem can be inferred from considerations about ecosystem survival and growth without relying on internal-process descriptions. An important and favourable consequence of this climate- and ecosystem-driven approach is that it provides a physical justification for catchment models that do not rely on soil information and on the complexity associated with the description of soil water dynamics. Another consequence is that modelling water movement in the soil, if required, can benefit from the constraints that are imposed by the embedding ecosystem. Here we illustrate our ecosystem perspective of hydrological processes and the arguments that support it. We suggest that advancing our understanding of ecosystem water management strategies is key to building more realistic hydrological theories and catchment models that are predictive in the context of environmental change. To reference this document use: http://resolver.tudelft.nl/uuid:010d5ea8-4444-4db8-b71d-d345ee2714c2 DOI https://doi.org/10.5194/hess-27-2607-2023 ISSN 1027-5606 Source Hydrology and Earth System Sciences, 27 (14), 2607–2620 Part of collection Institutional Repository Document type journal article Rights © 2023 Hongkai Gao, Fabrizio Fenicia, Hubert Savenije Files PDF hess_27_2607_2023.pdf 6.28 MB Close viewer /islandora/object/uuid:010d5ea8-4444-4db8-b71d-d345ee2714c2/datastream/OBJ/view