Evaluation of the erosion risk of Tokat province

Soil erosion is recognized as a significant environmental problem caused by the combination of intensive tillage, land degradation, and severe rainfall events. Furthermore, due to dramatic changes in the hydrological cycle brought on by climate change, it is anticipated that soil erosion will increase even further in the future. Therefore, various management techniques, equations, and models have been developed to estimate soil loss in a given area. In recent years, models based on logical, mathematical, and physical processes have come to the forefront in assessing soil detachment, transport, and deposition. Among these, the Universal Soil Loss Equation (USLE) and the Water Erosion Prediction Project (WEPP) are among the most widely used approaches. This study was conducted in the districts of Almus, Artova, Başçiftlik, Erbaa, Merkez, Niksar, Pazar, Reşadiye, Sulusaray, Turhal, Yeşilyurt, and Zile, located within Tokat Province. Annual soil losses were estimated using the USLE and WEPP models for areas with different slope classes and land use types (cropland, pasture, and forest), and the results were compared to evaluate the overall erosion risk for the province. According to the WEPP model, the annual average soil loss was estimated to range from 0.02 to 89.71 ton/ha/year in croplands, 0.00 to 10.52 ton/ha/year in pastures, and 0.00 to 5.56 ton/ha/year in forest lands. The USLE model estimated soil losses between 1.62–69.55 ton/ha/year for croplands, 0.29–2028 ton/ha/year for pastures, and 0.023–1.202 ton/ha/year for forests. The comparison of the two models revealed that the WEPP model predicted, on average, 9.28 ton/ha/year more soil loss in croplands and 4.95 ton/ha/year more in forest areas compared to the USLE model. On the other hand, in pasture areas, the USLE model predicted 9.76 ton/ha/year higher soil loss than the WEPP model. According to the results of both models, a systematic increase in soil loss was observed with increasing slope, and erosion risk was found to rise significantly in steeper areas.