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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Flow energy and channel adjustments in rills developed in loamy sand and sandy loam soils
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Flow energy and channel adjustments in rills developed in loamy sand and sandy loam soils

机译：壤质沙质和砂质壤土中小溪的流动能和通道调整

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摘要

The storms usually associated with rill development in nature are seldom prolonged, so development is often interrupted by interstorm disturbances, e.g. weathering or tillage. In laboratory simulated rainfall experiments, active rill development can be prolonged, and under these conditions typically passes through a period Of intense incision, channel extension and bifurcation before reaching quasi-stable conditions in which little form change occurs. This paper presents laboratory experiments with coarse textured soils under simulated rainfall which show how channel adjustment processes contribute to the evolution of quasi-stability. Newly incised rills were stabilized for detailed study of links between rill configuration and flow energy. On a loamy sand, adjustment towards equilibrium occurred due to channel widening and meandering, whereas on a sandy loam, mobile knickpoints and chutes, pulsations in flow width and flow depth and changes ill stream power and sediment discharge occurred as the channel adjusted towards equilibrium. The tendency of rill systems towards quasi-stability is shown by changes in stream power values which show short-lived minima. Differences in energy dissipation in stabilized rills indicate that minimization of energy dissipation was reached locally between knickpoints and at the downstream end, of rills. in the absence of energy gradients in knickpoints and chutes, stabilized rill sections tended toward equilibrium by establishing uniform energy expenditure. The study confirmed that energy dissipation increased with flow aspect ratio. In stabilized rills, flow acceleration reduced energy dissipation on the loamy sand but not on the sandy loam. On both soils flow deceleration tended to increase energy dissipation. Understanding how rill systems evolve towards stability is essential in order to predict how interruptions between storms may affect long-term rill dynamics. This is essential if event-based physical models ire to become effective in predicting sediment transport on rilled hillslopes under changing weather and climatic conditions. Copyright (C) 2008 John Wiley and Sons, Ltd.
机译：自然界中通常与小溪发展有关的暴风雨很少延长，因此暴风雨之间的干扰经常会中断发展，例如风化或耕作。在实验室模拟的降雨实验中，可以延长小溪的活跃发育，并且在这些条件下通常要经过一段时间的剧烈切口，通道扩展和分叉，然后才达到准稳定条件，在这种情况下几乎不会发生形式变化。本文介绍了在模拟降雨条件下使用粗糙纹理土壤的实验室实验，这些实验表明通道调节过程如何有助于准稳定性的演变。稳定了新切开的小钻，以详细研究小钻构型与流动能之间的联系。在壤质砂土上，由于河道加宽和曲折而向平衡方向进行了调整，而在壤质壤土上，移动的拐点和斜槽上，随着河道向平衡面方向的调整，出现了水流脉宽和水深的脉动以及不良的水力和沉积物排放。溪流系统趋于准稳定的趋势通过流功率值的变化来表示，这表明寿命极短。稳定小溪中的能量耗散差异表明，小溪的拐点之间和下游端局部达到了能量耗散的最小化。在没有拐点和斜槽的能量梯度的情况下，稳定的小溪部分会通过建立均匀的能量消耗而趋于平衡。研究证实，能量耗散随流动纵横比的增加而增加。在稳定的小溪中，水流加速作用减少了壤土上的能量耗散，但没有减少砂土上的能量耗散。在这两种土壤上，流量减速都倾向于增加能量耗散。为了预测风暴之间的中断如何影响长期的钻探动态，了解钻探系统如何朝着稳定发展至关重要。如果基于事件的物理模型无法有效地预测在不断变化的天气和气候条件下钻孔山坡上的泥沙输送，则这是至关重要的。版权所有（C）2008 John Wiley and Sons，Ltd.

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