چكيده لاتين
The Komeh watershed, located in the southern part of Isfahan Province, due to its geomorphological and climatic characteristics—including steep slopes, weak marl–shale lithology, shallow soils, and intense convective rainfall events—is considered one of the areas with very high erosion and sediment yield potential in the Central Zagros region. The absence of an active sediment gauging station within the watershed makes the application of integrated and indirect approaches essential for the quantitative estimation of sediment yield. In this study, sediment production and erosion status in the Komeh watershed were assessed by integrating data from the Marbar reference basin, transferring specific discharge and runoff coefficients, hydrological analyses, empirical and semi-empirical models (USLE, PSIAC, and EPM), remote sensing techniques, and spatial processing within a GIS environment. Initially, the annual runoff of 17 sub-watersheds was estimated using the Justin method, which was identified as the most accurate approach based on statistical performance criteria. Subsequently, by employing the sediment rating curve of the Sarbaz hydrometric station, the suspended sediment load and total sediment yield of the reference basin were calculated and then transferred to the Komeh watershed. The results indicated that the annual sediment production of the watershed ranges between 1.8 and 2.5 million tons per year, while the specific sediment yield was estimated to be 1,200–1,500 tons per square kilometer per year. According to global sediment yield classifications, these values indicate a condition of very severe sediment production. Spatial analysis of the PSIAC and EPM models revealed that approximately 50% of the watershed area falls within the “high” and “very high” erosion risk classes. The southern and southwestern sectors of the watershed exhibit the highest erosion susceptibility, primarily due to slopes exceeding 20%, weak marl–clay soils, high drainage density, and poor vegetation cover. The results of multiple regression analysis demonstrated that slope (β = 0.58), soil type (β = 0.37), and land use (β = 0.31) are the most influential factors contributing to increased erosion, whereas vegetation cover (β = −0.44) plays a fundamental role in reducing erosion intensity. The spatial overlap among the applied models and their consistency with statistical results confirm the reliability and robustness of the integrated methodological framework adopted in this study. Based on the erosion zoning maps, the southern parts of the watershed were identified as critical areas, requiring urgent management interventions, including gully and channel stabilization, terracing, grazing control, and vegetation restoration. The findings of this research provide a scientific basis for integrated watershed management planning, sediment control, and soil conservation strategies in the southern region of Isfahan Province.
