Modeling best management practices and nature-based solutions for sediment and nutrient reduction with SWAT: A systematic review of parameterization approaches.

Agricultural non-point source pollution remains a predominant cause of water quality impairment globally, necessitating effective mitigation strategies. Best Management Practices (BMPs) and Nature-Based Solutions (NBSs) have emerged as essential measures for reducing nutrient and sediment loads while maintaining agricultural productivity. The Soil and Water Assessment Tool (SWAT) model has been extensively used to evaluate and compare BMPs' and NBSs' impacts on water quality. However, model parameterization is still a critical issue. This systematic review, following PRISMA guidelines, analyzed 59 peer-reviewed studies published between 2002 and 2024 to synthesize SWAT model parameterization approaches for simulating BMPs and NBSs. At the catchment scale, vegetative filter strips achieved 8-99% sediment reduction and 15-71% nutrient reduction. Conservation tillage and contour farming resulted in 17- 80% and 7.5- 51% sediment reduction, respectively, depending on spatial scale and site conditions. Key hydrological, sediment, and nutrient parameters showed significant variability across studies, reflecting the context-dependency of model parameterization. The review identified inconsistencies in parameter selection and limited standardization of the representation of BMPs and NBSs in SWAT. This synthesis provides evidence-based parameter ranges and implementation guidelines for 12 major BMPs and NBSs, thereby facilitating improved water-quality modeling to support policy decisions on agricultural pollution control.