Sediment supply to VHA watercourses (2020)

Soil erosion leads to sediment transport through the landscape until sedimentation occurs on land or the sediment flow reaches watercourses, canals or sewage. This layer of data reflects the modelled sediment supply to watercourses of the Flemish Hydrographic Atlas (VHA), expressed in tonnes of sediment that reaches these watercourses on average annually at a given location. The modelling was performed with the CN-WS model version 4.2.2 in combination with pycnws version 0.5.4. The calculation took place on a Flanders scale at a resolution of 20 m. This data layer is an indication of the average sediment supply calculated with an average precipitation erosivity factor over the last 30 years. Scenario A was applied, where agricultural parcels are considered grassland when they have permanent crop cover for at least 2 consecutive years. All other agricultural parcels are considered an average arable land. The modelling is based on the agricultural parcel map of 2020. Account was taken of the erosion measures implemented in 2020 through management agreements or through small-scale erosion control works. Locally, the modeled values can deviate from the real values, given that each modeling is only an approach to reality. In addition, only the input data available and part of the model can be taken into account.