A trapping capacity constraint model for sediment transport in vegetative filter strips (VFS) on sloping surfaces,Hydrological Processes

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A trapping capacity constraint model for sediment transport in vegetative filter strips (VFS) on sloping surfaces
Hydrological Processes ( IF 2.8 ) Pub Date : 2023-03-29 , DOI: 10.1002/hyp.14868
Songbai Wu _{1,

2} , Ting Fong May Chui ₂ , Chen Li ₃ , Mingjie Luo ₄ , Chengzhong Pan ₅

Affiliation

Most current modelling practices for sediment trapping in vegetative filter strips (VFS) assumed a constant sediment trapping efficiency of VFS, while, in practice, it was found to decrease greatly with the increasing trapped sediment amount in VFS (decreasing sediment trapping capacity of VFS). To account for this impact, a widely used VFS sediment transport module was modified to consider the changing sediment trapping capacity of VFS, which was expressed by a power-law relationship with the inflow discharge, sediment concentration, slope gradient, and antecedent deposition amount. An integrated model that coupled a slope infiltration-runoff module and the modified sediment transport module was then developed to simulate hydrology and suspended sediment transport in VFS on sloping surface. The model is calibrated and validated by 18 VFS experiments with different inflow, sediment, and slope conditions from Luo et al. (Science of the Total Environment, 725, 138361, 2020). Good agreements between observed and simulated runoff and sediment transport processes were found for nearly all cases. Due to the impact of changing sediment trapping capacity of VFS, the trapped sediment amount and the sediment transport rate of outflow varies greatly in space and time. With the increase of inflow discharge, sediment concentration, and slope gradient, the overall sediment trapping efficiency of VFS tends to decrease greatly and then remains almost unchanged. The comparison between proposed model and original physically based model shows that neglecting the impacts of changing sediment trapping capacity of VFS would lead to a constant and overly large sediment trapping efficiency of VFS, especially on steep slopes. Moreover, comparing with the empirical expression, the model with well-founded theory can provide higher fidelity and more detailed results. Thus, the modelling framework is expected to provide a more effective approach for VFS assessment and maintenance in local or watershed scale.

中文翻译：

斜面上植物性过滤带 (VFS) 泥沙输运的捕获能力约束模型

大多数当前的植物过滤带 (VFS) 泥沙捕集建模实践假设 VFS 的泥沙捕集效率恒定，而在实践中，发现随着 VFS 中捕集泥沙量的增加而大大降低（VFS 的泥沙捕集能力降低） . 为了考虑这种影响，修改了广泛使用的 VFS 泥沙输送模块，以考虑 VFS 不断变化的泥沙捕集能力，这通过与流入流量、泥沙浓度、坡度梯度和前期沉积量的幂律关系表示。然后开发了一个耦合斜坡入渗径流模块和修改后的泥沙输运模块的集成模型，以模拟 VFS 在斜面上的水文和悬浮泥沙输运。该模型通过 18 个 VFS 实验进行校准和验证，这些实验具有 Luo 等人的不同入流、沉积物和坡度条件。(整体环境科学, 725, 138361, 2020). 在几乎所有情况下，观察到的和模拟的径流和沉积物输送过程之间都存在良好的一致性。由于受VFS截留泥沙量变化的影响，截留泥沙量和出流泥沙输移速率在空间和时间上变化很大。随着入流流量、泥沙浓度和坡度的增加，VFS 的整体泥沙捕集效率趋于大幅下降，然后几乎保持不变。所提出的模型与原始基于物理的模型之间的比较表明，忽略变化的 VFS 泥沙捕集能力的影响将导致 VFS 的泥沙捕集效率恒定且过大，特别是在陡坡上。此外，与经验表达式相比，具有良好理论基础的模型可以提供更高的保真度和更详细的结果。因此，该建模框架有望为局部或流域规模的 VFS 评估和维护提供更有效的方法。

更新日期：2023-03-29

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