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The estimation of water erosion with RUSLE and deposition model : A case study of the Bin El-Ouidane dam catchment area (High Atlas, Morocco)

Nouaim Wafae, Rambourg Dimitri, El Harti Abderrazak, Ettaqy Abderrahim, Merzouki Mohamed, Karaoui Ismail

Journal of Water and Land Development

2023

no. 58

136--147

Water erosion is a critical issue for Morocco, especially in its semi-arid regions, where climatic and edaphic conditions only allow erratic soil formation and vegetation growth. Therefore, water erosion endangers human activity both directly (loss of arable land, landslides, mudflows) and indirectly (siltation of dams, river pollution). This study is part of the Kingdom’s effort to assess the risk of water erosion in its territory. It is dedicated to the Bin El-Ouidane dam water catchment, one of the biggest water storage facilities in the country, located in the High Atlas Mountains. The poorly developed soils are very sensitive to erosion in this mountainous area that combines steep slopes and sparse vegetation cover. The calculation of soil losses is carried out with the RUSLE model and corrected by estimating areas of deposition based on the unit stream power theory. This method produces a mean erosion rate of around 6.3 t·ha-1·y-1, or an overall annual loss of 4.1 mln t, consistently with the siltation rate of the dam. Primary risk areas (erosion rates > 40 t·ha-1·y-1) account for 54% of the total losses, while they cover only 7% of the catchment. This distribution of the soil losses also shows that the erosion risk is mainly correlated to slope, directing the means of control toward mechanical interventions.

Assessing the intra-annual variability of agricultural soil losses: a RUSLE application in Nord-Pas-de-Calais, France

Nouaim Wafae, Rambourg Dimitri, Merzouki Mohamed, El Harti Abderrazak, Karaoui Ismail

Journal of Water and Land Development

2022

no. 52

210--220

The control of water erosion is an important economic and societal challenge. Reduction of the agronomic potential of the parcels, muddy flows, siltation of dams are harmful consequences that mobilize farmers, water managers, local authorities and scientific researchers. This study focuses on mapping and quantifying seasonal soil losses in the territory of the former Nord-Pas-de-Calais administrative region, using the Revised Universal Soil Loss Equation (RUSLE) which incorporates five factors: rainfall erosivity, soil erodibility, topography, land use and erosion control practices. The seasonal (3-months) time scale is chosen to better account for the parameters governing the soil water erosion, especially rainfall and vegetation cover, that show great asynchronous intra-annual variability. Also, high resolution data concerning agricultural plots allows to evaluate which type of culture are the more subject to soil losses. In Nord-Pas-de-Calais, water erosion occurs almost ubiquitously, but the areas characterized by steep slopes are the most at risk (Artois Hills and Flanders), with loss rates up to 54 t∙ha-1∙y-1. The majority of erosion occurs during fall (46% of the computed annual losses of 1.69∙Mt), on plots left bare after harvest (especially corn and beets crops). The study also demonstrates that extending the intercrop technique over the region, and therefore maintaining a fall and winter cover, could reduce the soil losses by 37%.

Evaluating the potential of Sentinel-2 satellite images for water quality characterization of artificial reservoirs: The Bin El Ouidane Reservoir case study (Morocco)

Karaoui Ismail, Arioua Abdelkrim, Boudhar Abdelghani, Hssaisoune Mohammed, Mouatassime Sabri El, Ouhamchich Kamal Ait, Elhamdouni Driss, Idrissi Abdelkhalek El Amrani, Nouaim Wafae

Meteorology Hydrology and Water Management. Research and Operational Applications

2019

Vol. 7, Iss. 1

31--39

Monitoring water quality in large dams is becoming a necessity for protecting stored water from various forms of pollution. This process requires analysis of several samples on a weekly or monthly basis. Our study aims to determine the relationship between water quality parameters (WQP) and digital data from the Sentinel-2 satellite to estimate and map the WQP in the Bin El Ouidane Reservoir. The in situ sampling was carried out in the Bin El Ouidane Reservoir (Azilal Province), followed by analysis of physicochemical parameters in the laboratory. These measurement results were compared with the reflectance in each sampling location to investigate the correlations between bands and laboratory chemical analysis results. The correlation results showed that all studied parameters have an R2 greater than 0.52, and they can be transformed to predictive models by stepwise regression. The accuracy of our proposed models was tested using the Oum Er-Rbia Hydraulic Basin Agency data, and the results showed that only three parameters yield admissible verification results (Chlorophyll A, dissolved Oxygen and Nitrate). Those models were then used in geographic information system software to produce a thematic map of each parameter over the entire surface of the reservoir. As a conclusion, the Sentinel-2 images could help indicate the eutrophication stage in the Bin El Ouidane Reservoir, which is a major risk in major Moroccan reservoirs.