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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >The evolution of gully headcut morphology: a case study using terrestrial laser scanning and hydrological monitoring
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The evolution of gully headcut morphology: a case study using terrestrial laser scanning and hydrological monitoring

机译：沟渠切口形态的演变：使用地面激光扫描和水文监测的案例研究

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摘要

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 (c) 2015 John Wiley & Sons, Ltd.
机译：我们目前对沟渠冲刷侵蚀的观测和分析，在空间和时间方面与以往的冲刷研究不同。通过在三年内进行的十次陆地激光扫描（TLS）调查，我们在一年一度的基础上绘制了具有厘米级细节的喷头侵蚀。通过点云微分可以观察到侵蚀变化，通过揭示头部形态的演变，扩展了以前的头部退缩率研究。将冲切撤离观测与水文测量相结合，以探索侵蚀性撤退的控制因素。我们发现：（i）由于润湿而导致的质量破坏;（ii）切入池中的页岩基岩的饱和度减弱;（iii）顶切面上的直接冲洗似乎都有助于顶切后退;然而，通过润湿引起的质量破坏似乎是主要过程。在0.4m深度的研究头切面附近监测土壤湿度，延时照片显示，降雨和融雪径流事件发生后，土壤湿润趋向于沿着头切点集中。我们发现，在顶切顶点处的水分浓度比在顶切侧壁处导致更快的侵蚀，从而导致半椭圆形平面视图形态在顶切向高谷迁移时得以维持。版权所有（c）2015 John Wiley＆Sons，Ltd.

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