Abstract:
Soil loss by runoff is a severe and continuous environmental and infrastructural problem
in Kulfo watershed. Deforestation and improper cultivation have resulted in accelerated
viii
soil erosion. Information on soil loss is essential to support agricultural productivity and
watershed management. Thus, study was aimed to estimate and map the soil loss by using
GIS and RUSLE techniques raster format in GIS environment. Topographic map of
1:250,000 scale. Aster Digital Elevation Model (DEM) of 30 m spatial resolution. digital
soil map of 1:250.000 scales, fifteen years rainfall records of six stations nearby
watershed. and land sat imagery (ETM+) with spatial resolution of 30m were used to
derive RUSLE's soil loss parameter. The RUSLE parameters were analyzed and
superimposed using raster calculator in the geo-processing tools in ArcGIS10.2
environment to estimate and map the annual soil loss of the study area. The result showed
that the mean annual soil loss of the watershed range from none significant (0 tons ha
-1
y
-1
)
to highly sever (253.38 ton ha
-1
y
-1
). The mean annual soil loss of the whole watershed was
88.57 tons ha
-1
y
-1
. The total annual soil loss in the watershed was 3,862,077 ton per year
from 39900 ha of land. Most of these soil erosion affected are spatially situated in the
upper steepest slope part and middle part of the watershed. This area where acrisols with
high soil erodibility character are dominant Hence, Slope gradient and length followed by
soil erodibility factors were found to be the main factors of soil erosion .The
morphological character also the determinant factor for soil and water conservation
practice. Thus, sustainable soil and water conservation practices should be adopted in the
most sever area of the watershed.
