Specific sediment supply (2020)

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 area classification is based on the intermediate catchment areas, as defined by the VMM. The modelling was performed with the CN-WS model version 4.2.2 in combination with pycnws version 0.5.4. 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 2020 agricultural parcel map. The erosion control measures implemented in 2020 through management agreements or through small-scale erosion control 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.