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Towards the regionalization of hydraulic and plant‐soil parameters for modelling soil moisture conditions of a catchment
Author(s) -
Van Berg Jan A. Den
Publication year - 2007
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.3290140616
Subject(s) - water content , pedotransfer function , environmental science , infiltration (hvac) , soil science , soil water , hydrology (agriculture) , macropore , evapotranspiration , soil texture , loam , moisture , hydraulic conductivity , field capacity , soil morphology , geology , soil classification , geotechnical engineering , ecology , mesoporous material , biochemistry , chemistry , biology , catalysis , physics , materials science , composite material , thermodynamics
Computational simulation of the moisture regime of the soil is a useful help in studying land potential, ecology, and land degradation processes such as soil erosion and mass movement. The utility of modelling soil moisture depends on the validity of the model structure and of the model parameters. Moreover, except for differences in relief and for variation in rainfall and net radiation, such a model will show spatial variability only if the variability of the ecological properties of the soil and the vegetation canopy can be input. Eight experimental sites on erodible loamy to silty soils in the Ardèche Basin, France, were investigated, to ascertain how the information required for modelling soil moisture can be obtained. Three terms of the soil moisture budget were measured or determined for compiling the model structure: rainfall, soil moisture content (or capillary pressure head), and actual evapotranspiration. The latter was calculated with the Bowen ratio method from the energy balance measured at three sites. These data were also to calculate the canopy resistance in the evaporation formula based on transport resistances. To study how to regionalize the hydraulic parameters, the characteristic of unsaturated conductivity and soil moisture diffusivity as a function of moisture content or capillary pressure head were determined by the hot air method for intermediate moisture contents and with the crust method on soil columns in situ for high moisture contents. Estimation of the diffusivity from soil texture appeared to be less successful for fine‐textured soils. Macropores apparently crucially influenced the capacity of ponding infiltration and the frequency of overland flow.