Soil erosion is a major problem in Morocco. However, few studies have addressed this phenomenon in Central Morocco. This paper presents the results of a quantitative study of water erosion in Ben Ahmed watershed (70 km Southeast from Casablanca). Several rainfall simulations using an intensity of 60mm h-1during one hour have been undertaken on the major soil types of the watershed. Results showed that soil detachability varied between 19 and 34g l-1and erosion rates ranged between 4.3 and 12.3t ha-1. Also 38 to 73% of rainfall was transformed into runoff. Laboratory analysis of soil samples has confirmed that the studied soils present low organic matter (1.2 to 3.3%) and bulk density ranges between 1.1 and 1.5 g cm-3.

Keywords: Water erosion, Runoff, Detachability, Rainfall simulation, Central Morocco