Specific sediment supply (2022)

Soil erosion leads to sediment transport through the landscape until sedimentation occurs on land or the sediment flow reaches watercourses, canals or sewers. This data layer shows the areas with the modelled specific sediment supply to watercourses of the Flemish Hydrographic Atlas (VHA), canals and sewerage, expressed in tonnes of sediment that reaches the water system on average annually per hectare. For this purpose, the total sediment input into the area is divided by the area of the area. The zoning is based on the intermediate catchment areas (A1 areas), as defined by the VMM in the context of the 2022-2027 River Basin Management Plans. The modelling was carried out with the CN-WS model version 4.2.3 in combination with pycnws version 0.6.3. The calculation was done on a scale of Flanders at a resolution of 20 m. This data layer is an indication of the average sediment supply calculated with an average precipitation erosivity factor of the last 30 years. Scenario A was applied, whereby agricultural parcels are considered grassland when they have a permanent crop cover for at least 2 consecutive years. All other agricultural parcels are considered to be average arable land. The modelling is based on the 2022 agricultural parcel map. The anti-erosion measures implemented in 2022 through management agreements or small-scale anti-erosion works were taken into account. Locally, the modelled values may differ from the real values, as each modelling is only an approximation of reality. Moreover, only the input data that is available and part of the model can be taken into account.