Soil erosion is a major cause of land degradation. It can be estimated with several models, such as empirical, conceptual and physical based. One of the empirical models used worldwide nowadays for soil erosion assessment is the Universal Soil Loss Equation (USLE) and its updated form, the Revised Universal Soil Loss Equation (RUSLE). In Morocco, this model is being used to assess and quantify soil loss by water erosion. In spite of this, it was noted that limited studies employed correctly this important tool. The goal of this review paper was to identify potential usage of R/USLE models in Morocco. This was done by evaluating the conducted studies concerning these models and main gaps and challenges were determined accordingly. Improvement options and future requirements for using R/USLE models were recommended. In order to assess the statues of the R/USLE models applications, the 56 published documents related to R/USLE models conducted in Morocco during the first use till 2020 were collected and reviewed. These publications covered five main areas. The main benefits as well as gaps of the conducted studies were discussed for each area. Current concerns, need of future studies as well as related recommendations and suggestions were also presented.

Rainwater harvesting (RWH) is an alternative technique to potentially overcome the increasing need for water. However, identifying suitable sites for RWH remains a complex task. The present study offers an approach that can enable water managers to use the Water and Tillage Erosion Model and Sediment Delivery Model (WaTEM/SEDEM) as a spatially soil erosion and sediment delivery model, Geographic Information System (GIS) and Fuzzy Analytical Hierarchy Process (FAHP) method to identify potential RWH sites. For this purpose, several data sources were employed to generate needful thematic layers. Five criteria: land use/land cover (LULC), slope, soil texture, drainage density and runoff were used. The Soil Conservation Service-Curve Number (SCS-CN) method was utilized for preparing a yearly runoff potential map. Then, the thematic layers were weighted for generating RWH suitability map. The results show that the average annual runoff is 248 mm. Moreover, approximatly 76.1% of the study area falls within slight soil erosion class. The classified RWH suitability map showed that 6.9% of the watershed falls within an extremely suitable category. Prediction accuracy of the developed map of RWH suitability showed an area under the curve value (AUC) of 59.6% for FAHP method in this study. It is concluded that involving a spatial soil erosion and sediment delivery model with GIS-based FAHP represents a valuable approach for locating suitable RWH sites. So, this method can be used in other parts of the world.