From research to practitioners: catchment-scale operationalization of nature-based solutions in runoff and erosion modelling

There is a growing interest in the use of nature-based solutions (NbS) to mitigate natural hazards. However, limited parameterization exists for runoff, erosion, and mudflow models, preventing upscaling of NbS effects to the catchment scale for management purposes. In this study, a parameterization of NbS such as fascines, hedgerows, grass strips, and ponds is proposed and implemented in a catchment-scale runoff and erosion model applicable by non-experts (WaterSed). The model was applied to a 1,245 ha pilot site in Northern France. The model facilitated landowner and stakeholder engagement, enabling co-construction of management plans at the river basin scale (≈2,650 km2) through model transfer to local river basin management authorities. The model enables spatial optimization of local NbS implementation, reducing sediment load at the catchment outlet from 50 to 82%. This a priori evaluation of management plans is a prerequisite for local stakeholders to apply for financial support for NbS implementation. In return, feedback from local observations helped improving the model parameterization at scales that could not be achieved by traditional research approaches. This study therefore demonstrates the interest of the proposed framework for both scientists and practitioners.