Introduction
Soil erosion is highly significant as a spatiotemporal phenomenon in
many countries (Fistikoglu and Harmancioglu, 2002; Hoyos, 2005; Pandey
et al.,2009). Soil erosion is a natural process, where the extent and
magnitude of soil loss are controlled by various environmental
determinants, such as topography, climate, soil and vegetation
(Wischmeier and Smith, 1978; Renard et al., 1997; Mutua et al., 2006;
Butt et al., 2010). There are several factors that increase water
erosion which are: rainfall, soil type, slope, vegetation type and
presence or absence of conservation measures (Khalid chadli, 2016).
In Morocco, soil erosion has been increasing annually. Indeed, in recent
decades, the agricultural areas has undergone considerable changes, with
specific degradation and soil loss rates, varying from region to another
and mainly ranging from 5 to 20 t/ha/year (Ghanam, 2003).
To date, most studies on soil erosion at large scale have used numerous
soil erosion and sediment transport models. In fact, modeling provides
quantitative estimation of soil loss in a reasonable time-frame under a
wide range of conditions, compared to the field-based methods. In
Morocco, research works dealing with soil erodibility and erosion risk
were undertaken at different scales. El Garouani et al. (2005) used the
USLE in the Oued Jemaa basin (Pre-Rif zone in the North of Morocco). For
large scale mapping, El bouqdaoui et al. (2005) used the expert-based
model LEAM (Land Erodibility Assessment Model), based on the USLE and
satellite imagery to evaluate soil loss rates in the Oued Srou Basin.
Universal Soil Loss Equation (USLE) (Wischmeier & Smith, 1978) and
Revised Universal Soil Loss Equation (RUSLE) (Renard et al., 1997) are
the most widely used models because of their simplicity, robustness and
transparent model structure, minimal data requirement, easy input data
availability as well as the compatibility with geospatial platforms
(Millward & Mersey, 1999; Merritt et al., 2003). Despite the inherent
limitations of USLE and RUSLE, the versatility of these models
integrated with GIS was demonstrated in a wide range of environmental
settings and at various spatial scales (Prasanna-kumar, Vijith et al.,
2011; Prasannakumar, Shiny et al., 2011; Ranzi, Le, & Rulli, 2012;
Mhangara, Kakembo, & Lim, 2012; Panagos et al., 2015; Pradeep et al.,
2015; Magesh & Chandrasekar, 2016; Abdo & Salloum, 2017; da Cunha,
Bacani, & Panachuki, 2017 ; Haregeweyn et al., 2017).
The objective of the present study is to assess the amount of soil loss
at Ben Ahmed watershed based on USLE method and GIS (Geographical
Information System) techniques, and to prepare potential soil erosion
maps of the Ben Ahmed watershed.