Evaluation of GUEST and WEPP with a new approach for the determination of sediment transport capacity
Evaluation of GUEST and WEPP with a new approach for the determination of sediment transport capacity
复制标题
DOI：
10.1016/j.jhydrol.2014.03.060
复制
发表时间：
2014-05
影响因子：
6.4
通讯作者：
M. Mahmoodabadi;H. Ghadiri;C. Rose;Bofu Yu;H. Rafahi;H. Rouhipour
中科院分区：
文献类型：
--
作者：
M. Mahmoodabadi;H. Ghadiri;C. Rose;Bofu Yu;H. Rafahi;H. Rouhipour
输沙能力(TC)是所有基于过程的侵蚀模型的关键参数。本研究的目的是开发一种基于细沟形态和泥沙反馈关系的准确确定入渗条件下Tc值的新方法。这将允许在WEPP和客户模型中计算泥沙输送能力的方法。三种土壤中6米长的细沟在恒定入流速率(50、75和122mlS−1)和三种水槽坡度(2%、4%和6%)下进行试验。在每次试验之前和之后，使用轮廓仪以0.5米的间隔精确测量细沟的横截面。每一段末端的累积净侵蚀率被换算为沿细沟长度的泥沙负荷。应用泥沙反馈关系对泥沙负荷值进行了拟合，并在平衡条件下渐近确定了Tc值。结果表明，在入渗条件下，两种模型都有低估Tc值的趋势，但使用Guest模型预测的Tc值与实测值的一致性要好于用WEPP预测的Tc值。使用建议的值Off=100.15，可以进一步提高客户在预测Tc方面的性能。侧壁坍塌被发现是WEPP低估Tc值的一个合理的解释，而WEPP没有明确地建模。相反，Guest考虑了观察到的细沟形态的任何变化。结果还表明，Tc随流量和坡度的增加而增大，但对坡度的敏感性大于流量。此外，流功率被发现比剪切应力更能预测Tc值。然而，使用单位流量和坡度作为自变量的回归方程并不比客体(当f=0.15时)对Tc的估计更好。在基于流程的模型中使用的参数(S)的准确确定将导致改进的Tc估。此外，TCI是一个基于过程的参数，理想情况下不应使用回归方程进行估计。
Sediment transport capacity (Tc) is a key parameter for all process-based erosion models. The objective of this study was to develop a new approach for accurate determination ofTcunder infiltration conditions based on rill morphology and the sediment feedback relationship. This would allow the way in which sediment transport capacity is computed in WEPP and GUEST models. Six-m long rills in three soils were subjected to constant inflow rates (50, 75 and 122 ml s−1) and three flume slope gradients (2%, 4% and 6%). Cross-sections of rills were measured precisely at 0.5 m intervals using a profile-meter prior to and after each experiment. The cumulative net rates of erosion at the end of each section were converted to sediment load along the rill length. The sediment feedback relationship was applied to fit the sediment load values andTcwas determined asymptotically under equilibrium conditions. The results showed that under infiltration conditions, both models tended to under-estimateTc, however,Tcpredicted using the GUEST model had better agreement with the measuredTcvalues than that predicted with WEPP. Using the proposed value ofF= 0.15, the performance of GUEST in predictingTccould be further improved. Sidewall slumping was found to be a plausible explanation for underestimation ofTcby WEPP, which is not explicitly modeled. In contrast, GUEST takes into account any observed changes in rill morphology. The results also indicated thatTcincreased as a function of flow discharge and slope gradient, but was more sensitive to slope gradient than to flow discharge. Moreover, stream power was found to be a better predictor ofTcthan shear stress. Yet, regression equations using unit discharge and slope gradient as independent variables, did not achieve any better estimation ofTcthan did the GUEST (whenF= 0.15). Accurate determination of parameter(s) used in a process-based model such as GUEST will lead to improvedTcestimations. Furthermore,Tcis a process-based parameter which should not ideally be estimated with regression equations.