Mapping of soil erosion for soil and water conservation measures in Kolleru lake catchment area

摘要

Mapping of soil erosion assumes significance for land use planning and watershed management. Erosion can be predicted by integrating meteorological, topographical, field survey and satellite data in GIS environment. The spatial and temporal variationof soil erosion map has been generated for the Kolleru lake catchment. The areas under different classes of soil erosion risk have been worked out. The Kolleru lake catchment area is 6252 km2. The elevation of the catchment varies from 0 to 532 m. The catchment has been divided into subbasins based on the outlet points of drains and rivers (Budameru, Ramileru Tammileru and Gunderu) flowing into the Kolleru Lake. Majority of soils are sandy clay loam (45%) in texture. There are 12 types of land uses in the catchment with major area under agriculture. Soil erosion has been estimated for a period of 23 years (1990 to 2012). The quantitative potential soil loss through erosion in the catchment was estimated by universal soil loss equation with the relevantinformation on factors like erosivity (R), soil erodibility (K), topographic factor (LS), cover and land management factor (C) and conservation practice factor (P). The values of R, K, LS, C and P factors were used for generating maps of each factor. About 16% area is under the slight erosion (51 ha^yr1). Moderate erosion (5-101 ha^yr"1) occurs in about 37% area. High and very high erosion occurs in 13% and 14% area, respectively. Severe erosion (>20 tha1 yfl) occurs in 20% area of the catchment. Basedon severity of soil erosion, suitable sites for check dams and percolation tanks on 2nd/3rd order streams were identified using thematic maps of the catchment area.