Quantification of soil loss in various lithological areas of the western Middle Atlas Central: application to the Ras-Elma, Tamelalet and Sebab watershed (Tigrigra watershed, Morocco)

¹ Laboratory for Geo-Environmental Analysis, Planning - DD, Sidi Mohammed Ben Abdellah University - Fez.
² Laboratory of Soil Microbiology and Environment, Moulay Ismail University, Meknes
³ Laboratory of Molecular Chemistry and Natural Substance, Moulay Ismail University, Meknes

^* Corresponding address: hassan.achiban@usmba.ac.ma

Abstract

The present study proposes to evaluate the extent of erosion according to the lithology in three sub-watersheds (Ras Elma, Sebab and Tamelalet) belonging to the Tigrigra basin and evolving in humid climatic context. The methodology adopts the revised universal soil loss equation (RUSLE). The results obtained make it possible to establish erosion class maps via GIS. A clear spatial difference in soil loss is observed, between the three sub-basins and in proportion to the lithology: on average 42.15 t/ha/year on Paleozoic schistose soils, against 17.06 t/ha/year on carbonate substrates Mesozoic and 8.46 t/ha/year on quaternary basalts. Correlations between soil loss and RUSLE factors are established. Soil infiltration regimes on different substrates are studied.