Determining soil loss in Burdur lake watershed using the GIS and wepp model

Erosion is a natural situation that has been experienced since the existence of the world. Today, soil erosion is accepted as one of the most serious environmental problems. In a region; it is important to be known the distribution of soil erosion in soil and water conservation studies carried out by taking into account the degree of deterioration of the lands. The fact that erosion measurements are both costly and time consuming has led to the development of many erosion prediction models. WEPP model, which is one of these erosion prediction models and forms the basis of our study, is one of the most important erosion prediction methods. In this research, the WEPP model was applied in the experimental plots established with geotextiles under different land use forms (agriculture, forest, pasture) in the Burdur Lake Watershed. It is aimed that estimation of soil losses, determination of sediment and comparison of obtained results with observed sediment values. In this study, 4 model watersheds were selected from 52 sub-watersheds by considering the bedrock, land use, slope and aspect factors and and including 120 from 0-20 cm and 120 from 20-40 cm depth level, in total, 240 soil samples whose natural structure was degraded and 240 undegraded (cylindrical) were taken. The total erosion in number 1 model watershed from the model watersheds where geotextile parcels are established was calculated as 3.17 ton/ha/year in the first year; the second year 2.56 ton/ha/year; in the number 5 watershed model, the first year 8.81 ton/ha/year; second year 8.67 ton/ha/year; in the number 20 model watershed, the first year 13.55 ton/ha/year; the second year 13.18 ton/ha/year and erosion in the number 30 model watershed, 7.27 ton/ha/year in the first year; the second year 10.45 ton/ha/year. The amount of soil transported in the Burdur Lake Watershed was calculated as 186 221.0 ton/ha/year in 2019-2020 and 197 994.0 ton/ha/year in 2020-2021. With the GeoWEPP model, the annual average soil loss in the experimental plots established in the model watersheds (1-5-20-30) is estimated respectively; 2189.7 ton/year, 2758.8 ton/year; 11865.0 ton/year; 2991.0 ton/ha/year. It has been determined that the total sediment yield in Burdur Lake Watersheds is 135 780.6 ton/ha/year, and the annual average sediment yield is 0.426 ton/ha/year in total.