Optimizing Watershed Sediment Management: A Multi-objective Approach Balancing Erosion Control, Ecosystem Services, and Economic Costs

Soil and water conservation practices (SWCPs) are fundamental strategies for interrupting sediment connectivity and mitigating soil erosion at the watershed scale. However, traditional design approaches often overlook the spatial heterogeneity of sub-basins and the complex trade-offs between environmental benefits and economic costs. This study proposes a novel multi-objective optimization framework to identify optimal SWCP configurations that balance ecosystem service value (ESV), life-cycle investment costs (IC), and sediment yield reduction. Using the Soil and Water Assessment Tool (SWAT) coupled with a non-dominated sorting genetic algorithm (NSGA-III), we evaluated fifteen SWCP scenarios (combining terracing, contour farming, and check dams) . The results demonstrate that combined SWCPs significantly outperform individual measures in disrupting sediment transport, with the combination of terracing, contour farming, and boulder check dams achieving the highest reductions in sediment yield (SY). While higher investment costs generally correlate with greater sediment reduction, our optimization reveals that low-cost practices like contour farming provide efficient connectivity management despite lower ESV. The optimized solution identified in this study reduced SY by 4.496 × 10⁵ t and streamflow by 36.84 × 10⁵ m³ with a minimal IC of 4.61 × 10⁶ CNY, effectively maximizing the cost-benefit ratio. These findings provide a scientific basis for sustainable watershed management, offering policymakers a tool to navigate the challenges of balancing erosion control, ecological restoration, and economic constraints.