Estimating Annual Amount of Soil Loss Over University of Benin Using RUSLE, GIS and Remote Sensing Methods

Abstract

The present study is aimed to estimate the annual soil loss of
University of Benin gully. This was achieved by utilizing the Revised
Universal Soil Loss Equation, RUSLE coupled with GIS Technique. A
total of 15 samples were collected from the gully site, three at each
chainage point. The soil analysis showed that the study area is highly
sandy with low clay and silt content. This study area has very high
infiltration rate, ranging from 93.64-2509.06 mm/hr. Result obtained
for soil organic content revealed that organic matter content in the
soil samples is small, ranging from 0.17 to a highest value of 2.30.
Soil Erodibility ranges from 0.002 to 0.01ton ha hr (ha MJ mm).
This result is due to the soil texture being mainly sandy, as sand can
be easily detached. On annual basis, the Rainfall-runoff erosivity
value for the study area is very high. The study also found that Cover
Management factor, is low and uniform throughout the gully site.
On the whole, the study found high annual soil loss, ranging from
1.509-7.545 ton/ha/yr. The maximum amount of estimated soil loss is
determined as 7.545 ton per hectare per year which equals 75.45
kilogram per square kilometre per year (kg/sq. km/yr). Conservation
planning and land use policies should be developed to focus on the
more prone slopes, which are likely to suffer immensely from the
directional influence of rainfall. The implementation of such an
approach should be aimed at arresting directional rainfall erosion by
the integration of various erosion control measures. Finally, dumping
of refuse on the river channels and floodplains should be prohibited.
Government and the University Management should enact and
enforce laws to deter such activities.