Land sediment routing (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 represents the modelled sediment flow direction and the amount of sediment flowing in that direction, expressed in tonnes of sediment flowing in a given direction on average annually. The arrows visualize the direction and sediment quantity from a sediment transport of 2.5 tons per year. 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 transport 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.土壤侵蚀会引发泥沙在地表景观中运移，直至泥沙在陆面沉积，或泥沙流汇入河道、沟渠与排水管网。本数据图层展示经建模得到的泥沙运移方向与对应运移量，量化单位为年均沿特定方向运移的泥沙吨数。本图层中的箭头用于可视化呈现泥沙运移方向与运移量级，其参照基准为年运移量2.5吨的泥沙运移场景。本次建模采用CN-WS模型4.2.3版本，并结合pycnws 0.6.3版本完成。本次计算覆盖法兰德斯（Flanders）全域，空间分辨率为20米。本数据图层基于近30年平均降水侵蚀力因子计算得到，用于表征年均泥沙运移状况。本研究采用场景A：若农业地块连续2年及以上保有永久作物覆盖，则将其归类为草地；其余所有农业地块均按普通耕地进行处理。本次建模以2022年农业地块图为基础底图。建模过程中已纳入2022年通过管理协议或小型水土保持工程落地的各项侵蚀防治措施。