The evolution of gully headcut morphology: a case study using terrestrial laser scanning and hydrological monitoring
The evolution of gully headcut morphology: a case study using terrestrial laser scanning and hydrological monitoring
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DOI：
10.1002/esp.3721
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发表时间：
2015-08
影响因子：
3.3
通讯作者：
F. Rengers;G. Tucker
中科院分区：
文献类型：
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作者：
F. Rengers;G. Tucker
我们目前的意见和分析沟头切侵蚀，这不同于以往的头切研究在空间和时间上的细节。使用在3年内进行的10次地面激光扫描（TLS）调查，我们以分年度为基础绘制了具有厘米级细节的头部侵蚀。通过点云差分观察侵蚀变化，通过揭示水头形态的演变，扩展了以前的水头后退速率的研究。结合水文观测资料，探讨侵蚀后退的控制因素。我们发现，（一）由于润湿的质量故障，（二）饱和弱化的页岩基岩在水垫塘，和（三）直接洗过的头切面都出现有助于头切撤退，但是，通过润湿的质量故障似乎是占主导地位的过程。在0.4 m深的研究开挖点附近监测土壤湿度，延时照片显示，降雨和融雪径流事件后，土壤润湿倾向于沿着开挖点顶点集中。我们发现，与沿沿着的侵蚀相比，水头顶点处的水分浓度导致该位置的侵蚀更快，从而导致在水头向上迁移时保持半椭圆形平面视图形态。版权所有© 2015约翰威利父子有限公司.
We present observations and analysis of gully headcut erosion, which differ from previous headcut studies in both spatial and temporal detail. Using ten terrestrial laser scanning (TLS) surveys conducted over a period of 3 years, we mapped headcut erosion with centimeter‐scale detail on a sub‐annual basis. Erosional change is observed through point cloud differencing, which expands on previous studies of headcut retreat rate by revealing the evolution of the headcut morphology. Headcut retreat observations are combined with hydrological measurements to explore the controlling factors of erosional retreat. We find that (i) mass failure due to wetting, (ii) saturation weakening of shale bedrock in plunge pools, and (iii) direct wash over the headcut face all appear to contribute to headcut retreat; however, mass failure via wetting appears to be the dominant process. Soil moisture was monitored near the study headcut at 0.4 m depth, and time‐lapse photos show that soil wetting tends to be concentrated along the headcut apex after rainfall and snowmelt runoff events. We find that moisture concentration at the headcut apex leads to more rapid erosion at that location than along the headcut sidewalls, resulting in a semi‐ellipsoidal plan view morphology that is maintained as the headcut migrates up‐valley. Copyright © 2015 John Wiley & Sons, Ltd.