Publication Details |
| Category | Text Publication |
| Reference Category | Journals |
| DOI | 10.5194/hess-25-983-2021 |
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| Title (Primary) | Sigmoidal water retention function with improved behaviour in dry and wet soils |
| Author | de Rooij, G.H.; Mai, J.; Madi, R. |
| Source Titel | Hydrology and Earth System Sciences |
| Year | 2021 |
| Department | BOSYS |
| Volume | 25 |
| Issue | 2 |
| Page From | 983 |
| Page To | 1007 |
| Language | englisch |
| Topic | T5 Future Landscapes |
| Supplements | https://doi.org/10.5194/hess-25-983-2021-supplement |
| Abstract | A popular parameterized soil water retention curve (SWRC) has a hydraulic conductivity curve associated with it that can have a physically unacceptable infinite slope at saturation. The problem was eliminated before by giving the SWRC a non-zero air entry value. This improved version still has an asymptote at the dry end, which limits its usefulness for dry conditions and causes its integral to diverge for commonly occurring parameter values. We therefore joined the parameterizations' sigmoid midsection to a logarithmic dry section ending at zero water content for a finite matric potential, as was done previously for a power-law-type SWRC. We selected five SWRC parameterizations that had been proven to produce unproblematic near-saturation conductivities and fitted these and our new curve to data from 21 soils. The logarithmic dry branch gave more realistic extrapolations into the dry end of both the retention and the conductivity curves than an asymptotic dry branch. We tested the original curve, its first improvement, and our second improvement by feeding them into a numerical model that calculated evapotranspiration and deep drainage for nine combinations of soils and climates. The new curve was more robust than the other two. The new curve was better able to produce a conductivity curve with a substantial drop during the early stages of drying than the earlier improvement. It therefore generated smaller amounts of more evenly distributed deep drainage compared to the spiked response to rainfall produced by the earlier improvement. |
| Persistent UFZ Identifier | https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=24311 |
| de Rooij, G.H., Mai, J., Madi, R. (2021): Sigmoidal water retention function with improved behaviour in dry and wet soils Hydrol. Earth Syst. Sci. 25 (2), 983 - 1007 10.5194/hess-25-983-2021 |
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