Soil Crack Dynamics as Driver for Preferential Flow in Clay-Rich Soils
Abstract
Soil cracking is widely recognized as a driver of preferential flow in clay-rich soil. Nevertheless, soil crack dynamics are still not completely understood and their implementation into preferential flow models and its parametrization is challenging. Therefore, the aim of this study is to identify soil crack dynamics in time and its feedback on soil moisture, to develop relationships for modeling the effects of soil structure on water flow in clay-rich soils.
For this, the surface extent of soil cracks was measured during the summer of 2016 for three plots in a corn field in Luxembourg. Time-lapse pictures of the soil surface were taken at 1h resolution. Furthermore, soil moisture was recorded in three depths (5, 10 and 20 cm) and vertical anisotropy of apparent electrical resistivity measurements was used to estimate the crack depth dynamic. We digitized soil cracks from the soil surface images and calculated crack area. The time-series of crack area and geometrical characteristics of crack patterns were analyzed as well as the dynamics of opening and closing with meteorological forcing (precipitation, short-wave radiation). We found that surface soil cracks opened and closed quickly, but that the soil moisture response was still fast after crack closing. This suggests that cracks only close at the surface during initial rainfall events, but that preferential flow and high infiltration rates persist below the surface soil layer. Electrical resistivity anisotropy measurements indicated that soil cracks at depth only closed after multiple precipitation events and with high rainfall amounts. We used these observations to parameterize the infiltration module of the model RoGeR (Runoff Generation Research Model) to improve infiltration and surface runoff prediction during heavy precipitation. The model results were also validated against sprinkling experiments at two clay-rich sites with observable soil cracks in Germany.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H41O2321D
- Keywords:
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- 1838 Infiltration;
- HYDROLOGYDE: 1847 Modeling;
- HYDROLOGYDE: 1865 Soils;
- HYDROLOGYDE: 1875 Vadose zone;
- HYDROLOGY