TITLE:
Potential Erosion Risk Calculation Using Remote Sensing and GIS in Oued El Maleh Watershed, Morocco
AUTHORS:
Hicham Lahlaoi, Hassan Rhinane, Atika Hilali, Said Lahssini, Loubna Khalile
KEYWORDS:
Watershed Oued El Maleh, Erosion, USLE, Geographic Information System
JOURNAL NAME:
Journal of Geographic Information System,
Vol.7 No.2,
April
10,
2015
ABSTRACT: Oued El Maleh watershed is
considered the largest ocean basin of the Chaouia-Ouardigha region in Morocco.
Severe flooding occurred in 1996, 2001 and 2002 in the watershed. Thus,
significant economic and human damage has been caused. The floods of Mohammedia
city, located in the outlet of the watershed, were due to the silting of the
Oued El Maleh dam which has lost its ability to retain water. This work,
therefore, aims to assess soil losses by water erosion in the Oued El Maleh
watershed through modeling main factors involved in water erosion. The
methodology used is based on the use of the universal soil loss equation
(USLE). The model includes the following factors: soil erodibility, the
inclination of slopes, the rainfall erosivity, vegetation cover and erosion
control practices. The aggressiveness of rainfall was calculated for a number
of stations bordering the study area and interpolated across the watershed
using geostatistical model. Soil erodibility was extracted from soil map and
soil survey. The effect of topography was approached by combining the degree of
slope and slope length using a digital elevation model (ASTER) and ArcHydrology
extension (ArcGIS). The vegetation cover was derived from Landsat image ETM
through the supervised classification method. The index of erosion control
practices was approached by field visits. All factors have been measured and
integrated into a geographic information system which enabled us to spatialize
the degree of sediment production at the watershed scale in a synthetic map.
The annual soil loss is 8.21 t/ha/yr and the soil loss classification shows
that surfaces affected by high erosion are equivalent to 10% of the watershed.
Furthermore, this map is available to support land managers policy makers in
the process of decision making related to soil conservation, infrastructure and
citizens’ property protection.