Soil erosion estimation and mapping using detailed soil survey and GIS: Need for soil conservation in hilly areas, tropical humid region, India

Heavy rainfall in humid tropical regions (annual average 3911 mm) causes soil erosion and damage through landslides. Using the universal soil loss equation (USLE), we estimated soil loss, sediment yield (SY) and sediment load (SL) in Elamdesam (total area 18750.51 ha) in Idukki district, Kerala, via a soil survey. The slope varied from 0 to over 33%. The USLE's rainfall erosivity R-factor was 1498.69 mm ha-1hr-1yr-1; the soil erodibility factor (K) ranged from 0.41 to 0.69, and the LS factor from 0.092 to 18.37. The cropping management factor (C) was 0.006 for rubber and 0.28 for paddy. The conservation practice factor (P) ranged from 0.40 to 0.65. Estimated soil erosion was low (0-5 t ha-1yr-1) in 22 mapping units (12909.48 ha), very severe (> 40 t ha-1yr-1) in five (4694.43 ha), low (5-10 t ha-1yr-1) in two (743.32 ha), and moderate (10-20 t ha-1yr-1) in two (403.26 ha). SY varied from 0.841 to 23.196 t ha-1yr-1, and SL ranged from 372.58 to 47089.98 t ha-1yr-1. The increase in soil erosion rate can be traced to rainfall severity, land cover (LC) changes, vegetation loss, and Ap horizon erosion. S2hG2, S6iH2, S1hH2, S1fH2g1, and S9hB2 experienced soil erosion rates over 40 t ha-1yr-1, marking them as high-risk zones for erosion. Implementing soil conservation measures to achieve land degradation neutrality (LDN) and prevent further soil loss, energy depletion and economic losses is crucial.