Enhancing Erosion Hazard Mapping Using 2D Hydraulic-Sediment Transport Models: A Case Study from Slovenia

In Slovenia, flood hazard mapping follows a standardized model-based procedure, defined by the EU Floods Directive. On the other hand, erosion hazard mapping remains largely empirical due to the absence of a unified methodology. Recent advances in 2D hydraulic and morphodynamic modelling offer new opportunities to integrate sediment processes into hazard assessments. This study enhances the current empirical approach to erosion hazard mapping by applying a combined 2D hydraulic-sediment transport model using HEC-RAS software version 6.4.1 and the Selška Sora River (Slovenia) as the case study area, comprising 300 ha of floodplains. Incorporating hydraulic variables and soil characteristics, the method identifies erosion-prone zones and classifies hazard levels. For the case study area, 21.9 ha of floodplains were identified as subject to erosion, and 23.9 ha as prone to deposition. Additionally, 43.8 ha of floodplains fall within the low, 1.9 ha within the medium, and 0.1 ha within the high erosion hazard class. The presented approach not only supports the national hazard mapping framework in Slovenia but also has potential applicability within broader EU hazard assessment practices.