Abstract
Soil erosion is one of the major factors that contributes to land degradation in the up and mid country of Sri Lanka. It is important to assess the rate of soil erosion under different environmental and socio-economic contexts to identify and apply suitable management interventions. A number of parametric models have been developed to predict soil erosion at drainage basins. Yet Universal Soil Loss Equation (USLE) is the most widely used empirical equation for estimating annual soil loss from small agricultural lands. This study was carried out with the objective of developing a land degradation assessment model using a geospatial approach. The study area was Kandaketiya DS division in Badulla district. USLE together with some socio - economic factors were used to develop the model for predicting land degradation. Slope length (L) and slope gradient (S) factors were derived from Digital Elevation Model. Rainfall erosivity (R) factor was determined using a correlation developed for Sri Lanka in a past research. Soil erodibility (K) factor was derived from the soil map. Crop management (C) factor and Erosion control practices (P) factor related to land cover derived from remotely sensed data taken from the literature. Annual soil erosion was computed using the above factors. The computed soil erosion map was coupled with the socioeconomic factors on population density, agricultural land to man ratio, land to man ratio and number of Samurdhi beneficiaries to assess the land degradation severity. The results showed that marginal tea lands are the highest contributor to soil loss in the study area. According to the study, soil erosion and population density contributed more to the land degradation. A strong negative relationship was found between land degradation and land to man ratio. DOI: http://dx.doi.org/10.4038/tar.v21i4.3312 TAR 2010; 21(3): 361-367
Highlights
Land degradation in terms of soil erosion is a complex process and its multiple hidden social and environmental impacts are an increasing threat for the human existence (Hesadi et al, 2003)
The Universal Soil Loss Equation (USLE) has been designed as a method to predict average annual soil loss caused by sheet and rill erosion
Since rainfall induced soil erosion is the most influential factor in land degradation, more weight was assigned to this data layer during the analysis
Summary
Land degradation in terms of soil erosion is a complex process and its multiple hidden social and environmental impacts are an increasing threat for the human existence (Hesadi et al, 2003). Soil erosion is one of the main causes of land degradation and can be quantified by field experiments or predicted by using models. Land degradation models concern about runoff and soil erosion. They are used to identify complex interactions between physical and socio-economic processes. Land degradation assessment studies are very important for the sustainable development of the area. Considering the above background, this study was conducted with the objectives of developing a land degradation assessment model using a geospatial approach
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