Integrated Evaluation of Soil Erosion Hazard and Risk Management in the Oued Beht Watershed Using Remote Sensing and GIS Techniques: Impacts on El Kansra Dam Siltation (Morocco)
The initial state of the
Oued Beht watershed (430,728 ha) is characterized by a socio-ecological
vulnerability associated to the water erosion risk. Especially, the
consequences are chained and the soil loss alters its hydrological behavior and
its ability to protect functional and structural challenges (good land, El
Kansra dam, agricultural activities). In this perspective, this study suggests
a methodology, reproducible and generalizable, to assess the natural water
erosion risk (R). The approach used is based on spatial processing technology of
information to develop a spatial database and geographic information system
(GIS) concerning biophysical andtopoclimatic
parameters in the Oued Beht watershed. Thus, the risk analysis is obtained by
combining thematic maps of Susceptibility (S) and potential Consequences (C).
Although, the spatial analysis of maps obtained reveals the extent of
susceptibility involving land degradation, with the potential risks, which
generated a decrease in the storage capacity of El Kansra dam (?3.03 Mm3/year).
The results show that erosion is active on more than three quarters (3/4) of
the watershed, and a considerable loss of land with 8.36 Million tonnes per
year. In this way, flood analysis and study ofhydrometeorological events identified
the vulnerability of flood sites (hot-spot) contributing at 77%of El Kansra siltation dam. Therefore,
the consequence assessment is obtained by identifying risk elements and
estimating potential damage coefficient, which represents the financial gap
flow affecting the socio-economic context due to the erosion impacts.
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