Assessment of soil erosion factors in areas drained by river Kibisi in Bungoma county, Kenya
Chepkania, Levi S
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This study assesses soil erosion factors in parts of Bungoma and Mount Elgon districts forming Bungoma County drained by River Kibisi in Kenya. The overall purpose of the present study is to improve land management and reduce the impact of soil erosion in order to increase agricultural production. The study area has been negatively impacted on by increased soil erosion and land degradation in general. The specific objectives of the study are to assess the influence of land cover and land use on soil erosion and investigate the alternative land use or land cover types or such combinations that best control(s) soil erosion. The most important factors that determine the rate of soil erosion are rainfall, soil type, slope, land cover, land use and soil and water conservation practices. The main driving force is increase of population and human activities on land. Two important models/instruments have been used in this study. The first one is the RUSLE model which provides accurate estimation of soil loss using average annual rainfall (R), soil erodability factor (K), slope length of topographic factor (LS), land cover (C) and conservation practice factor (P). This model has been applied in the present study with fairly good results. The second one is the Geographic Information Systems (GIS) or geospatial information system. In order to determine soil erosion, Geographic Information Systems (GIS) techniques were combined with Revised Universal Soil Loss Equation (RUSLE) model to assess soil erosion factors in the study area. The geographic information required included spatial data which provides information about geometrical orientation, shape and size of features which are either physical i.e. valleys or mountains or political/administrative i.e. divisional boundaries at a place and their relative position with respect to the position of the same physical or political features to another place for comparison purposes and the non-spatial data or attributes data is the information provided in the tabular form in numerals about slope, erodibility, erosivity and different types of vegetation or land cover.