 Figure 1: Soil water model. P is precipitation, Eact actual evaporation, and S_rzmax root zone water holding capacity
Daily root zone and deep storage water for West Africa
To calculate regional soil water, a modified Thornthwaite-Mather model has been built. Fed with regional soil data and state-of-the-art satellite rainfall and radiation products, daily soil water has been modeled for 2006.
The regional soil water model applies a well established model structure that has been widely used in different parts of West Africa (Masiyandima et al. 2003; Friesen et al. 2005; Taylor et al. 2006). For the conversion of soil water to tension and hydraulic conductivity, the approach by van Genuchten (1980) was taken.
 Figure 2: Elevation map of the study region in [m]. Marked in red are the locations shown in Fig. 3.
The soil water model is based on a Thornthwaite-Mather approach (Thornthwaite and Mather 1955, Steenhuis and Van Der Molen 1986). A two reservoir, root zone and deep storage, soil water balance is computed in daily time steps.
 Figure 3: Soil water model input data and results for selected pixels. The X axis shows time, and the Y axis is in the units shown in the title of each graph
Based on regional data of water holding capacity, precipitation, and incoming solar radiation, soil moisture at two levels, root zone and deep storage, was calculated daily for 2006 (Fig. 3).
Using soil hydraulic properties in combination with regional soil texture data, the modeled soil water can be converted to soil water tension and hydraulic conductivity.
Click here to download animated (mpg) file:
Daily root zone soil moisture [mm] for 2006
Persons in charge: Jan Friesen, Nick van de Giesen
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