ASSESSMENT OF WATER EROSION DYNAMICS IN THE MOROCCAN’S CENTRAL PLATEAU FOR CURRENT AND FUTURE SITUATIONS USING RUSLE MODEL AND GEE PLATFORM: CASE STUDY OF KHAROUBA WATERSHED

Abstract

The Kharouba watershed, located upstream of the Ouljet Soltane dam, has a crucial importance by preserving water and soil resources in the area.Belonging to the Beht watershed, this part of the Morocco's Central Plateau is subject to a relatively high level of soil degradation.In this context, the present study was conducted to assess the spatio-temporal dynamics of Soil Loss (SL) in the Kharouba watershed during the period 2001-2023, and to predict SL rate for the future period 2041-2060 (2050s).The methodological approach integrates the RUSLE model through the dynamic nature of the erosivity (R) and the vegetation cover (C) factors, and the Google Earth Engine (GEE) platform as a tool for the computational tasks.The results indicate that 52 to 82% of the Kharouba watershed surface is subject to intense to severe erosion.Annual Soil Loss varied from 54.29 t/ha in 2011 to 27.38 t/ha in 2023.The spatial distribution of SL values is mainly controlled by the variability of the topographical factor (LS) showing a good correlation with SL (R 2 =0.58).While the temporal variability of SL annual average is jointly explained by fluctuations in R and C factors, demonstrating R 2 of 0.35 and 0.23 respectively with SL.Future projections in 2050s show that the average annual Soil Loss is expected to increase by 14 and 13% in the SSP2-4.5 and SSP5-5.8scenarios respectively compared to the current situation.In addition, this study makes it possible to calculate the quantities of lost soil that will cause silting of the Ouljet Soultane dam located at the downstream end of our watershed, and consequently to determine the lifespan of the dam.