3. Soil Loss Estimation

The soil loss estimated using soil erosion models is vital in evaluating the existing soil conservation practices and identifying priority areas and appropriate measures to control erosion. This chapter presents various soil erosion modelling and measurement techniques for soil loss assessment. The Universal Soil Loss Equation (USLE), an empirical modelling approach, is introduced along with its factors: rainfall erosivity, soil erodibility, slope length-gradient, land cover and management, and soil conservation practice factor. Also, the Modified USLE (MUSLE), which has a runoff factor in place of the rainfall factor, and the Revised USLE (RUSLE), which includes several process-based concepts, are discussed. The chapter introduces the Water Erosion Prediction Project (WEPP) and the European Soil Erosion Model (EUROSEM), the distributed, physically-based soil erosion models that can simulate soil loss under diverse land uses and hydrologic conditions. Also, the Soil Conservation Service (SCS) curve number method and the rational method used for estimating the runoff volume and peak runoff rate are included. The chapter discusses the soil loss measurements from runoff plots. The different size plots are discussed along with commonly used devices, namely the multislot divisor and Coshocton wheel.