EFFECTS OF LAND USE AND LAND COVER CHANGES ON SOIL EROSION IN SEMI-ARID REGIONS OF TURKEY; A CASE STUDY IN ALMUS LAKE WATERSHED

Abstract

Land use and land cover (LULC) changes, which are the major causes of soil erosion in watersheds are important processes of land degradation in the world. Erosion models are useful to investigate temporal changes in the past and estimate the future soil losses that might threat the sustainability of crop production. In this study, temporal changes (between 1990 and 2018) of soil loss under different LULC were investigated in a small watershed located in Almus, Turkey. Universal soil loss equation (USLE) was used to model soil loss in the watershed at a fine spatial resolution using geographic information techniques. Rainfall (R), soil erodibility (K), slope length and steepness (LS) and supporting and conservation practices (P) factors of USLE model were kept constant, while cover and management factor (C) was determined by based on LULC types in 1990 and 2018. Spatial and temporal changes in erosion risk were mapped. The maps obtained indicated that LULC change has have both reducing and increasing effects on erosion risk. The average soil loss in 1990 decreased from 0.312 to 0.308 t ha-1 year-1 in 2018. Coverage of low-risk class areas in the basin increased by 20.19 km2 between 1990 and 2018. The increase in mixed forest cover caused a significant decrease in erosion risk. The results demonstrated that LULC is the driving factor for increasing or decreasing in soil erosion at the watershed. Conversion of forests to agricultural lands disturbed the surface cover and increased the erosion risk. The results revealed the significant impacts of LULC changes on soil erosion potential in the Almus Lake Watershed.