Richards Equation at the Hillslope Scale: Can We Resolve the Heterogeneity of Soil Hydraulic Material Properties?
AffiliationBiosphere 2, University of Arizona
Department of Hydrology and Atmospheric Sciences, University of Arizona
MetadataShow full item record
PublisherJohn Wiley and Sons Inc
CitationBauser, H. H., Kim, M., Ng, W. R., Bugaj, A., & Troch, P. A. (2022). Richards equation at the hillslope scale: Can we resolve the heterogeneity of soil hydraulic material properties?. Water Resources Research, 58(12), e2022WR032294.
JournalWater Resources Research
Rights© 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution License.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractProcess-based modeling of soil water movement with the Richards equation requires the description of soil hydraulic material properties, which are highly uncertain and heterogeneous at all scales. This limits the applicability of the Richards equation at larger scales beyond the patch scale. The experimental capabilities of the three hillslopes of the Landscape Evolution Observatory (LEO) at Biosphere 2 provide a unique opportunity to observe the heterogeneity of hydraulic material properties at the hillslope scale. We performed a gravity flow experiment where through constant irrigation the water content increases until the hydraulic conductivity matches the irrigation flux above. The dense water content sensor network at LEO then allows mapping of the heterogeneity of hydraulic conductivity at a meter scale resolution. The experiment revealed spatial structures within the hillslopes, mainly a vertical trend with the lowest hydraulic conductivity close to the surface. However, the variation between neighboring sensors is high, showing that the heterogeneity cannot be fully resolved even at LEO. By representing the heterogeneity in models through Miller scaling we showed the impact on hillslope discharge. For the hillslope with the smallest heterogeneity, representing the dominant structures was sufficient. However, for the two hillslopes with the larger overall heterogeneity, adding further details of the local heterogeneity did impact the discharge further. This highlights the limitations of the Richards equation, which requires the heterogeneous field of material properties, at the hillslope scale and shows the relevance to improving our understanding of effective parameters to be able to apply the process-based model to larger scales. © 2022. The Authors.
NoteOpen access article
VersionFinal published version
Except where otherwise noted, this item's license is described as © 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution License.