Sedimentary feed to grass (2020)

Soil erosion results in sediment transport through the landscape until sedimentation occurs on land or the sediment stream reaches watercourses, graves or sewers. This data layer represents the modelled sedimentary feed to graves that are not part of the Flemish Hydrographic Atlas (VHA), expressed in tonnes of sediment that reaches them on average annually at a given site. The modelling was carried out with the CN-WS model version 4.2.2 in combination with Pycnws version 0.5.4. The pass-through was done on a Flemish scale at a resolution of 20 m. This data layer gives an indication of the average sediment feed calculated with an average precipitation osivity factor of the last 30 years. Scenario A was applied, where agricultural parcels are considered grassland when they have permanent crop coverage for at least 2 consecutive years. All other agricultural parcels are considered to be average arable land. The modelling is based on the 2020 Land 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 deviate from real values, given that each modelling is only an approximation of reality. Moreover, only the input data available and part of the model can be taken into account.土壤侵蚀会导致泥沙在景观尺度内发生输移，直至泥沙在陆面沉积，或是泥沙径流进入水道、沟渠（graves）与下水道系统。本数据图层表征了未纳入弗拉芒水文图集（Flemish Hydrographic Atlas, VHA）的沟渠所接收的模拟泥沙补给量，以给定站点年均抵达该沟渠的泥沙吨数为量化单位。本次模拟采用CN-WS模型4.2.2版本结合Pycnws 0.5.4版本完成，模拟范围覆盖弗拉芒全区，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的年均泥沙补给量作为参考依据。本次模拟应用了情景A：即农业地块若连续两年及以上覆盖永久性作物，则归类为草地；其余农业地块均按常规耕地处理。模拟工作基于2020年土地地块图开展，并纳入了2020年通过管理协议或小型侵蚀控制工程实施的水土保持措施。由于每一项建模仅为现实的近似，且仅能采用现有输入数据与部分模型参数，局部区域的模拟值可能与实际值存在偏差。