A conceptual model of check dam hydraulics for gully control: efficiency, optimal spacing and relation with step-pools
A conceptual model of check dam hydraulics for gully control: efficiency, optimal spacing and relation with step-pools
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DOI：
10.5194/hess-18-1705-2014
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发表时间：
2014-05
影响因子：
6.3
通讯作者：
C. Castillo;R. Pérez;J. A. Gomez
中科院分区：
文献类型：
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作者：
C. Castillo;R. Pérez;J. A. Gomez
有很少的信息在科学文献中的修改引起的淤地坝系统内恢复冲沟河段的流量制度，尽管它是一个关键问题的设计冲沟恢复措施。在这里，我们开发了一个概念模型来分类流态在直矩形通道的初始和大坝填充条件以及估计效率的方法，以提供设计指南。该模型集成了几个以前的数学方法，用于评估所涉及的主要过程（水跃，冲击流，逐渐变化的流量）。确定了十种主要的流态分类，与IBER模型相比，产生了类似的结果。当将陡度系数c与设计数（DN，高度与坡度和临界深度乘积之比）绘制成图时，观察到最佳能量耗散（ODI）的区间。ODI的特点是最大能量耗散和总影响条件。我们的研究结果支持的最大流阻的原则，有效的间距范围内，而不是一个独特的配置的假设。发现c = 1和DN ~ 100的值在整个结构的不同沉积阶段经济地满足ODI条件。当我们的模型应用相同的参数的典型的阶梯池系统的范围内，预测结果落在一个类似的区域，在现场实验中观察到的。概念模型有助于解释间距频率分布以及经常被引用的趋势，以降低c的坡度增加阶梯池系统。这加强了一个假设的步骤，池单元和人为干预措施，通过检查坝的稳定配置之间的密切联系。
There is little information in scientific literature regarding the modifications induced by check dam systems in flow regimes within restored gully reaches, despite it being a crucial issue for the design of gully restoration measures. Here, we develop a conceptual model to classify flow regimes in straight rectangular channels for initial and dam-filling conditions as well as a method of estimating efficiency in order to provide design guidelines. The model integrates several previous mathematical approaches for assessing the main processes involved (hydraulic jump, impact flow, gradually varied flows). Ten main classifications of flow regimes were identified, producing similar results when compared with the IBER model. An interval for optimal energy dissipation (ODI) was observed when the steepness factor c was plotted against the design number (DN, ratio between the height and the product of slope and critical depth). The ODI was characterized by maximum energy dissipation and total influence conditions. Our findings support the hypothesis of a maximum flow resistance principle valid for a range of spacing rather than for a unique configuration. A value of c = 1 and DN ~ 100 was found to economically meet the ODI conditions throughout the different sedimentation stages of the structure. When our model was applied using the same parameters to the range typical of step-pool systems, the predicted results fell within a similar region to that observed in field experiments. The conceptual model helps to explain the spacing frequency distribution as well as the often-cited trend to lower c for increasing slopes in step-pool systems. This reinforces the hypothesis of a close link between stable configurations of step-pool units and man-made interventions through check dams.