Assessing the effects of agricultural terracing on water erosion rates using the RUSLE model in the Targa-n-Touchka watershed, Morocco

Effects of agricultural terracing on water erosion rates

Abstract

Implementing various soil conservation practices in rural agricultural regions underscores the need to evaluate their effectiveness in mitigating water erosion. Rural agriculture constitutes the main economic activity in the mountainous region of Morocco. In this study, the Targa-n-Touchka watershed (80 km2) located in the Anti-Atlas Mountains was selected as a typical case study to test the effectiveness of the old agricultural terracing on soil conservation using the Revised Universal Soil Loss Equation (RUSLE). The GIS integration incorporated variables to derive the spatial pattern of annual water erosion rates. These variables encompassed the rainfall erosivity factor (R), the soil erodibility factor (K), the slope length and slope steepness factor (LS), the cover management factor (C), and the support practice factor (P). The results mainly consist of a high-resolution thematic map illustrating a spatial distribution of soil loss, with an average annual soil loss of 2.76 t.ha-1. Field observation confirmed that areas most prone to erosion are generally the valleys and steep slopes, while hilly plains and well-managed slopes have a low erosion risk. Forcing abandoned terraces and constructing new ones are thus demanded to ensure this rural agricultural activity's sustainable protection, which is threatened.