Prediction of Recently Occurred Soil Erosion by Integrating Revised Universal Soil Loss Equation (RUSLE) with Geo-Spatial Techniques- A Case Study on Pettimudi Hills, Kerala-India

Abstract Soil erosion is the major cause for loss of soil fertility in many parts of the world. The conversion of forested areas into settlements and tea plantations has made Pettimudi hills in Iddukki district of Kerala prone to soil erosion. To compute the extent of soil erosion in the selected study area, the Revised Universal Soil Loss Equation (RUSLE) method is adopted. The present study analyses the soil erosion for the years (2017 to 2021) by varying the Land Use Land Cover (LULC) classes with constant R-factor (rainfall and runoff factor) and LS-factor (length-slope factor). The LULC for Pettimudi hills are classified into three categories, namely settlement, dense vegetation, and water bodies. An extreme rainfall event that took place on 6th of August 2020 resulted in drastic extensive soil erosion in the study area. The Supervised Classification method along with Maximum Likelihood Estimation techniques are used for LULC classification. The C-factor (Cover and management factor) ranges from 0 to 0.1 for the years 2017 to 2021 and is based upon the LULC classes identified in the study area. The conversion of vast areas of forest land into settlements and tea plantations decreases the soil organic matter and hydraulic conductivity of the soil which in turn increases the K-factor (soil erodibility factor), as found in the study area. The gathered results shows that the maximum erosion is seen in southern and north-western parts of the study area. The extent of soil erosion is seen to have increased from 0.25 tonnes/ha to 2.06 tonnes/ha in the time period of 2017 to 2021. It is observed that the 56 % of increase in the soil erosion during the study period is mainly due to LULC changes as well as with the extreme rainfall conditions in the area.