Using a modified PAP/RAC model and GIS-for mapping water erosion and causal risk factors: Case study of the Asfalou watershed, Morocco

Our work focuses on the assessment of trends, erosion states and causal risk factors for soil erosion of the Asfalou watershed through the use of the Priority Actions Program/Regional Activity Center (PAP/RAC). This qualitative study model for water erosion makes it possible to assess susceptibility and determine potential fragile areas in order to diagnose the state of soil degradation. We adopted the PAP/RAC crossed matrices, the geographic information system (GIS) and remote sensing (RS) to develop the classical modelling. This method is based on three main approaches: predictive, descriptive and integration. Introducing soil types, slope length (LS) and climatic factors into our model, including rainfall erosivity (R), slope exposure, soil moisture index (SMI) and land surface temperature (LST), improved the reliability of our model. The correlation analysis identified these factors that explain erosion states and the risk of soil erosion. The coefficients of determination (R-2) of the various erosive states resulting from the modified PAP/RAC approach explain respectively 98.30%, 77% and 49.3% of the observed variability of the erosive states. These factors provide information on the current state of soil degradation depending on the degree of influence of the different factors that control erosion. The descriptive approach has shown that soil loss manifests itself in different forms, whether for sheet erosion (L) and ravines (C1) successively affecting 79.95% and 17.84% of the land. The integration approach identifies factors and areas requiring intervention to counter the effects of soil erosion in the Asfalou watershed effectively and sustainably. (C) 2021 International Research and Training Center on Erosion and Sedimentation, China Water and Power Press, and China Institute of Water Resources and Hydropower Research. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.