A numerical model for duricrust formation by water table fluctuations
<p>Duricrusts are hard mineral layers forming in climatically contrasted environments. They form in tropical to arid environments and can be currently observed all around the world in areas such as Europe, Africa, South America, India, and Australia. In most cases, they cap hills and appear to...
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Copernicus Publications
2025-02-01
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| Series: | Earth Surface Dynamics |
| Online Access: | https://esurf.copernicus.org/articles/13/119/2025/esurf-13-119-2025.pdf |
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| author | C. Fenske C. Fenske J. Braun J. Braun F. Guillocheau C. Robin |
| author_facet | C. Fenske C. Fenske J. Braun J. Braun F. Guillocheau C. Robin |
| author_sort | C. Fenske |
| collection | DOAJ |
| description | <p>Duricrusts are hard mineral layers forming in climatically contrasted environments. They form in tropical to arid environments and can be currently observed all around the world in areas such as Europe, Africa, South America, India, and Australia. In most cases, they cap hills and appear to protect softer layers beneath. Two main hypotheses have been proposed for the formation of duricrusts; i.e. the hydrological or transported model, where the enrichment in the hardening element (iron for ferricretes, silica for silcretes, or calcium carbonates for calcretes) is the product of leaching and precipitation through fluctuations in the water table during contrasted seasonal cycles, and the laterization or in situ model, where the formation of duricrusts is the final compacting stage of laterization.</p>
<p>In this article, we present the first numerical geomorphological model for the formation of duricrusts based on the hydrological hypothesis. The model is an extension to an existing regolith formation model, where the position of the water table is used to predict the formation of a hardened layer at a rate set by a characteristic timescale, <span class="inline-formula"><i>τ</i></span>, and over a depth set by the range of fluctuations in the water table, <span class="inline-formula"><i>λ</i></span>. Hardening causes a decrease in surface erodibility, which we introduce in the model as a dimensionless factor, <span class="inline-formula"><i>κ</i></span>, that multiplies the surface transport coefficient of the model.</p>
<p>Using the model, we show under which circumstances duricrusts form by introducing two dimensionless numbers that combine the model parameters (<span class="inline-formula"><i>λ</i></span> and <span class="inline-formula"><i>τ</i></span>), as well as parameters representing external forcing like precipitation rate and uplift rate. We demonstrate that when using model parameter values obtained by independent constraints from field observations, hydrology, and geochronology, the model predictions reproduce the observed conditions for duricrust formation. We also show that a strong feedback exists due to duricrust formation on the shape of the regolith and the position of the water table. Finally, we demonstrate that although duricrusts protect elements of the landscape, their efficiency in doing so is significantly lower than their inherent strength.</p> |
| format | Article |
| id | doaj-art-8c59589ae5574d5f8595d25ab7b61905 |
| institution | Kabale University |
| issn | 2196-6311 2196-632X |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Earth Surface Dynamics |
| spelling | doaj-art-8c59589ae5574d5f8595d25ab7b619052025-02-03T11:43:08ZengCopernicus PublicationsEarth Surface Dynamics2196-63112196-632X2025-02-011311914610.5194/esurf-13-119-2025A numerical model for duricrust formation by water table fluctuationsC. Fenske0C. Fenske1J. Braun2J. Braun3F. Guillocheau4C. Robin5GFZ Helmholtz Centre for Geosciences, Telegrafenberg, 14473 Potsdam, GermanyInstitute of Geosciences, University of Potsdam, 14476 Potsdam, GermanyGFZ Helmholtz Centre for Geosciences, Telegrafenberg, 14473 Potsdam, GermanyInstitute of Geosciences, University of Potsdam, 14476 Potsdam, GermanyUniv Rennes, CNRS, Géosciences Rennes – UMR 6118, 35000 Rennes, FranceUniv Rennes, CNRS, Géosciences Rennes – UMR 6118, 35000 Rennes, France<p>Duricrusts are hard mineral layers forming in climatically contrasted environments. They form in tropical to arid environments and can be currently observed all around the world in areas such as Europe, Africa, South America, India, and Australia. In most cases, they cap hills and appear to protect softer layers beneath. Two main hypotheses have been proposed for the formation of duricrusts; i.e. the hydrological or transported model, where the enrichment in the hardening element (iron for ferricretes, silica for silcretes, or calcium carbonates for calcretes) is the product of leaching and precipitation through fluctuations in the water table during contrasted seasonal cycles, and the laterization or in situ model, where the formation of duricrusts is the final compacting stage of laterization.</p> <p>In this article, we present the first numerical geomorphological model for the formation of duricrusts based on the hydrological hypothesis. The model is an extension to an existing regolith formation model, where the position of the water table is used to predict the formation of a hardened layer at a rate set by a characteristic timescale, <span class="inline-formula"><i>τ</i></span>, and over a depth set by the range of fluctuations in the water table, <span class="inline-formula"><i>λ</i></span>. Hardening causes a decrease in surface erodibility, which we introduce in the model as a dimensionless factor, <span class="inline-formula"><i>κ</i></span>, that multiplies the surface transport coefficient of the model.</p> <p>Using the model, we show under which circumstances duricrusts form by introducing two dimensionless numbers that combine the model parameters (<span class="inline-formula"><i>λ</i></span> and <span class="inline-formula"><i>τ</i></span>), as well as parameters representing external forcing like precipitation rate and uplift rate. We demonstrate that when using model parameter values obtained by independent constraints from field observations, hydrology, and geochronology, the model predictions reproduce the observed conditions for duricrust formation. We also show that a strong feedback exists due to duricrust formation on the shape of the regolith and the position of the water table. Finally, we demonstrate that although duricrusts protect elements of the landscape, their efficiency in doing so is significantly lower than their inherent strength.</p>https://esurf.copernicus.org/articles/13/119/2025/esurf-13-119-2025.pdf |
| spellingShingle | C. Fenske C. Fenske J. Braun J. Braun F. Guillocheau C. Robin A numerical model for duricrust formation by water table fluctuations Earth Surface Dynamics |
| title | A numerical model for duricrust formation by water table fluctuations |
| title_full | A numerical model for duricrust formation by water table fluctuations |
| title_fullStr | A numerical model for duricrust formation by water table fluctuations |
| title_full_unstemmed | A numerical model for duricrust formation by water table fluctuations |
| title_short | A numerical model for duricrust formation by water table fluctuations |
| title_sort | numerical model for duricrust formation by water table fluctuations |
| url | https://esurf.copernicus.org/articles/13/119/2025/esurf-13-119-2025.pdf |
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