Sediment transport by land (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 represents the modelled sediment transport, expressed in tonnes of sediment flowing downstream on average annually at a certain location in the landscape. 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 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 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.土壤侵蚀会导致沉积物在地表景观中运移，直至发生陆地沉积，或是沉积物径流进入河道、沟渠或下水道。本数据图层展示经建模得到的沉积物运移量，以某一景观位置处年均向下游输送的沉积物吨数为单位进行表征。本次建模采用CN-WS模型4.2.2版本，并结合pycnws 0.5.4版本完成，计算范围覆盖法兰德斯地区，空间分辨率为20米。本数据图层基于近30年的平均降水侵蚀力因子计算得到。本次研究采用方案A：若农业地块连续两年及以上拥有永久性作物覆盖，则将其归类为草地；其余所有农业地块均被视作普通耕地。本次建模以2020年农业地块地图为基础开展，同时纳入了2020年通过管理协议或小型侵蚀防控工程实施的水土保持措施。需注意，在局部区域，建模结果可能与实际值存在偏差，因为任何建模都仅为现实情况的近似模拟；此外，仅能纳入建模可用的输入数据及模型本身可涵盖的信息。