3.1.1. Soil Erodibility

Soil erodibility parameters are presented in Figure 3. The dominant textural class in the basin was found to be loam (68.4%) followed by loamy sand (28.75%), while the remainder percentages are clay (2.48%) and sand (0.34%). In terms of texture, since most of the study area is covered by loam with respect to [62], the study area predominantly falls into the highly erodible class. In terms of soil depth, 94.6% of the Claise fits to the slightly erodible class (1000 mm > 750 mm), while the remainder 5.4% rests within the moderately erodible class (300 mm, corresponding to the 250–750 mm class). As far as stoniness is concerned, only 6% of the Claise is under the fully protected cover.

**Figure 3.** Spatial distribution of soil erodibility parameters: (**a**) texture, (**b**) depth, (**c**) stoniness, and class descriptions of the Claise with their respective indices.

Table 4 provides the numerical description of the soil's erodibility components.


**Table 4.** Numerical distribution of soil erodibility parameters and corresponding covered areas.

By inputting the texture, depth and stoniness parameters into the "raster calculator" tool of ArcGIS, the soil erodibility raster was generated and then reclassified using the "reclassify" tool (Figure 4).

**Figure 4.** Soil erodibility map of the Claise classified according to the CORINE indices.

As seen in Figure 4, the generated soil erodibility map revealed that about 96.83% (684.37 km2) of the study area is covered by highly erodible soils, while the remainder 3.17% (22.63 km2) correspond to moderate-risk areas. This fact is mainly due to the textural distribution of soil and the little stone cover of the Claise basin.
