Combination of empirical models and observational-based techniques in the quantification of soil loss: a case of Rherhaya watershed, High Atlas, Morocco

Abstract

Abstract The soils are naturally subjected to erosion, this natural and periodic phenomenon shapes the reliefs, under the combined effect of several drivers, and by the intermediary of certain agents such as the water, wind, etc. The eventual result of the rocks' deterioration and wear is a displacement and deposit where the sediments build up. The Rherhaya basin, Western High Atlas, Morocco, is among the areas most affected by erosion, the structure of its reliefs combined with the hierarchy of its rivers, as well as the lithology of the formations that constitute it play in the presence of other aggravating factors, a preponderant role in determining the rate of erosion in the region. Using GIS, the Revised Universal Soil Loss Equation (RUSLE) model, and the Erosion Potential Method (EPM) model, are applied in this study in order to quantify the annual soil losses in the Rherhaya basin. The results obtained by the RUSLE model are very consistent with the results measured, both in terms of volume, between 2.5 and 6.9 t/ha/yr as soil loss average volume observed versus 4.07 t/ha/yr calculated and 340 t/ha/year as the maximum volume observed versus 317.86 t/ha/year calculated. The maximum soil loss of 542 t/ha/yr and the average soil loss of 103 t/ha/yr are both overestimated by the EPM model, compared to the observed data.