## 5 Discussion
### Discussion of Soil Erosion Priorities
It is calculated by dividing the basin relief by the maximum length of the same basin [20]. The ruggedness number (\(Rn\)) can be defined as the result of the relationship between the maximum relief of a basin and drainage density [21]. The Rn results could be evaluated based on the elevation, variability, and slope of the contours. Sub-basin 13 had the lowest \(Rn\) value, indicating that the sub-basin was less prone to soil erosion and provided structural deformation in association with drainage density and relief. The remaining \(Rn\) values can be seen in Figure 9. Additionally, the lower Rn values suggested a low chance of soil erosion. The fifteen sub-basins examined in this study for priority zonation showed different stream orders. Sub-basin 10 presented the maximum stream order (fifth-order stream) (Table 2). All sub-basins provided fourth orders distributed over the entire Wadi Al-Lith Basin (Table 2). The extracted values of the sub-basin's geometric characteristics (basin area, basin perimeter, basin length, and average basin elevations) were as follows: the largest sub-basin in area and perimeter was basin number 5, covering approximately 458.20 km\({}^{2}\) and 118.5 km, respectively, at the eastern part of the study basin. Additionally, the geometric analysis of this basin revealed that the shortest basin length was recorded for sub-basin 8, located in the northeastern corner of the study basin. In terms of elevation, the highest elevation was recorded for sub-basin 13, at the eastern part of the basin, whereas the lowest elevation was observed for sub-basin 1. The elevation results showed that the general slope was toward the southern parts of the study basin. The results for the analyzed sub-basins are shown in Figure 5, and the stream orders and numbers are illustrated in Table 2. The authors in [40] applied the morphometric analysis in their study and suggested that morphometric parameters such as basin overland flow length, bifurcation ratio, relief ratio, ruggedness number, drainage texture, stream frequency, and drainage density provide a direct influence on soil erosion. Meanwhile, other morphometric parameters including the form factor, circularity ratio, compactness coefficient, and elongation ratio have an inverse relationship with the soil erosion process [9]. This suggestion could be translated as follows: in those morphometric parameters, where a direct relationship exists with the soil erosion process, a higher class (lower numerical values) should be expressed by the highest values of the applied morphometric parameters, namely, related morphometric parameters. In other words, the fifteen sub-basins in this study were exposed to analysis through every single parameter of the related parameters; then, the sub-basins were ordered from class 1 to class 15 due to the value of the applied morphometric parameter. Therefore, the lowest parameter value described class 1, while the highest parameter value was given for the sub-basin of class 15 (Table 5). In terms of this new scheme, the bifurcation ratio resulted in its lowest value for sub-basin 5, which, in turn, was translated to class 1. Thus, sub-basin 5(class 1; low related morphometric parameter value) provided the highest conditions of soil erodibility compared with the other 14 sub-basins. As another example, the drainage texture parameter resulted in it highest value for sub-basin 8, which, in turn, was described by class 15. Thus, sub-basin 8 (class 15; high related morphometric parameter value) provided the lowest conditions of soil erodibility compared with the other 14 sub-basins. On the other hand, the second group of morphometric parameters that showed an inverse relationship to the soil erosion process was applied in this study. These inverse parameters provided higher classes for the higher morphometric parameters.