Soil loss estimation of a watershed of central India with integration of geospatial techniques and universal soil loss equation

Soil erosion is a crucial problem and a critical environmental hazard in agricultural land, river catchments and reservoirs. Its assessment by various methods such as universal soil loss equation (USLE) is widely carried out by estimating the factors of the equation in a GIS environment. The Non-River catchment in Madhya Pradesh, India comprising of 836 sq. km area was studied for soil erosion and sediment losses in entirety as well as for its 33 sub catchments. The study revealed that a vertical fall of 230 meter with a sudden drop within 10 km generates a high erosion potential by runoff water in micro catchments numbered 1, 2, 3, 7, 21 and 29. The erosivity (R) parameter of catchment suggested of medium precipitation but high kinetic energy in western and southern part of the catchment. The topographic factor (LS) in western part of the catchments is higher which covers the sub catchments referred above. The forest land, fallow land and ravine lands comprising of 43.79% of the total catchment area are having sparse-vegetation and steep slopes, and are more prone to the soil erosion. In the Non River catchment no conservation practices are followed. The total annual rate of soil erosion in the catchment, as obtained by multiplying USLE factors, ranged variably under different land uses. The erosion from the steep and sparsely vegetated sub catchments under forest and fallows is highest in the range of 5.90–10.25 t/ha/yr. However, the agricultural land comprising of 50% of the catchment area is under the ‘slight’ class of the erosion ranging from 0.05 to 2.57t/ha/yr.

Soil erosion of fallow and sparse forests, where density of vegetation is very less, is varying from moderate to high. The annual rate of soil erosion in these sub catchments varies from 5.90 to10.25 t/ha/year, and as per revised tolerance limits such areas are not safer with respect to soil erosion hazard.

The upper reaches of the watershed are contributing the maximum soil loss, as these areas are degraded forests with high degree of slope. The middle reaches and lower reaches of the watershed are contributing average (<1 t/ha/yr) and moderate (1–5 t/ha/yr) soil loss.