Abstract:
Sedimentation of the reservoir is a function of soil erosion rate of the river catchment area which
reduces the water storage capacity of reservoir and availability of water for its designated use. Erosion of
topsoil from the catchment also reduces fertility and the vegetation growth as well. Negative effects of
sedimentation tend to become more and more relevant on a global scale due to population growth,
reduction of dense forests, severe climatic conditions etc. which facilitate more and more soil erosion. The
RUSLE model is the most commonly used model for estimation of spatial distribution of soil losses, soil
erosion risk and planning development and conservation plan under different land cover conditions
including croplands, rangelands, open and dense forests etc.
In the present study, an attempt has been made to estimate soil loss from the catchment of
Benisagar dam catchment using RUSLE model. The Benisagar dam is a medium project in drought prone
Rajnagar block Chhatarpur district of Bundelkhand region of M.P The dam has been constructed for
irrigation and supply water to historical Khajurah city. The ILWIS 3.6, a GIS software has been used for
preperation of thematic maps for the model. The detailed soil testing including soil texture, nutrient
analysis, infiltration rate and hydraulic conductivity have been carried out to determine the K-factor map.
The flow lengths for computation of SL-factor has been determined using DEM hydro processing module
of ILWIS. The Normal Deviation Vegetation Index (NDVI) has been used to estimate C-factor map and
land use map obtained from digital image analysis of LISS III data of IRS P6 has been used for extraction
of P-factor map. The results of analysis indicated that the average annual soil loss from the Benisagar
dam catchmewnt under present condition may be 8.23 t/ha/yr. The spatial distribution of soil loss obtained
from RUSLE model has been divided in to different classes of soil loss and it has been observed that
more than 50% of the study area falls in the range of 0.0 t/ha/yr to 5.0 t/ha/yr. The spatial distribution
obtained from the analysis may be useful for prioritization of sub watersheds and planning of soil
conservation measures and it may be concluded that 5.01 sq. km area having soil loss more than 10
t/ha/yr should be treated on priority basis.
