Evaluation of the erosion risk by means of the PAP/CAR model case the region of catchment Seklafa (Laghouat)

Abstract

The Seklafa catchment, with an area of 787 km², which is part of the Jebel Amour region (Algeria), is characterized by a spatio-temporal irregularity of the rains, a gap fairly high thermal, a deteriorated marly lithology and weak and unsuitable vegetation cover, which makes it subject to severe erosion in all its forms. It was therefore the subject of an assessment of erosive states and of the various causal factors of the soil risk erosion by the adaptation of crossed matrices on the basis of the PAP / RAC directives. The three constituent approaches (predictive, descriptive an interactive) are analyzed and mapped by GIS and remote sensing. The predictive approach shows that 28.1% of interest region area has high and very high erodibility. The PCA shows a linear and positive correlation with their causal factors such as; the erodibility (r = 0.799), the slope (r = 0.663), the protection of soil (r = 0.487) and the rocks hardness (r = 0.414). This may mean that these variables better explain erosive states. The descriptive approach showed that, sheet erosion and gully erosion are the most apparent processes in the study area, covering 45.2% and 19.7% respectively. The interactive phase highlighted the overall trends in the surface evolution of the watershed. In view of these results, the use of PAP / RAC in a GIS environment has many advantages,notably.those linked to the large number of results.