Resistance Formulations in Shallow Overland Flow Along a Hillslope Covered With Patchy Vegetation
Resistance Formulations in Shallow Overland Flow Along a Hillslope Covered With Patchy Vegetation
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DOI：
10.1029/2020wr027194
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发表时间：
2020-05
影响因子：
5.4
通讯作者：
O. Crompton;G. Katul;S. Thompson
中科院分区：
文献类型：
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作者：
O. Crompton;G. Katul;S. Thompson
描述表面粗糙度对流动阻力的影响仍然是使用Saint Venant方程（SVE）模拟浅层陆地流的一级挑战。这一挑战导致了将均匀粗糙表面的特性与体速度和阻力相关的粗糙度方案的激增，使得选择合适的粗糙度方案变得困难-特别是在非均匀表面上。对于水文预测，如果得到的SVE解决方案预测的结果，如径流和入渗之间的水平衡分配、山坡水文曲线和流量速度，其不确定性小于或与测量中的不确定性相当，则粗糙度方案是合适的。为了评估水文预测对粗糙度方案选择的敏感性，首先在平衡流量条件下对多个方案进行相互校准，同时在出口施加运动波近似。当应用于同一坡面和流量时，该方法得到了不同粗糙度方案参数之间的解析关系。利用该方法对5种常用的表面粗糙度方案进行了参数化，并对多斑状植被山坡的粗糙度方案进行了预测比较。结果表明，一旦校准，在广泛的降雨条件下，对粗糙度方案选择的预测敏感性极小。操作结果表明，参数化粗糙度方案在预测水文模式方面比采用精确公式更有意义。
Describing the effects of surface roughness on flow resistance remains a first‐order challenge for modeling shallow overland flow using the Saint Venant equations (SVE). This challenge has resulted in a proliferation of roughness schemes relating the properties of a uniform rough surface to bulk velocity and resistance, making selection of an appropriate roughness scheme daunting—especially on heterogeneous surfaces. For hydrological predictions, a roughness scheme is appropriate if the resulting SVE solutions predict outcomes such as water balance partitioning between runoff and infiltration, the hillslope hydrograph, and the discharge velocity with uncertainties that are less than or comparable to uncertainty in measurements. To assess the sensitivity of hydrological predictions to the choice of a roughness scheme, multiple schemes are first calibrated to each other under equilibrium flow conditions while imposing the kinematic wave approximation at the outlet. This approach yields analytical relations between the parameters of different roughness schemes when applied to the same hillslope and discharge. The approach is used to provide a parameterization of five commonly used roughness schemes for a common surface, and the predictions of the schemes for multiple patchily vegetated hillslopes are compared. The results suggest that, once calibrated, there is minimal prediction sensitivity to the choice of roughness scheme across a wide range of rainfall conditions. Operationally, the results demonstrate that parameterizing a roughness schemes is of higher significance for predicting hydrological patterns than the precise formulation employed.