RAPID: Patterns of Fluvial Sedimentation and Geomorphic Change Following an Extreme Flood Event

美国国家科学基金会地理空间科学（GSS）项目[1615154]allan JamesJohn kupfer南卡罗来纳大学这个快速反应研究项目将描述和量化2015年10月初发生在南卡罗来纳众多河流和溪流中的大洪水的影响。极端洪水会产生相当大的侵蚀和沉积，为研究严重洪水如何改变河道和洪泛平原提供了绝佳的机会。洪水结束后不久收集的短暂数据将提高对这些罕见的大洪水期间沉积物运移和沉积动力学的基本认识，以及它们在沉积记录中的重要性。特别是，水流功率高于某一阈值的持续时间将有助于预测何时何地会发生河岸和洪泛区侵蚀，侵蚀程度有多大，以及何时水流功率的变化率与沉积模式相一致。项目结果将加深对大洪水地貌调整的程度和性质的基本认识。它们将有助于指导市、县、州和联邦各级以及地方流域协会的决策者，并将使研究科学家能够为城市河流制定更有效的流域管理计划。该项目还将指导来自科学和工程领域代表性不足群体的研究生和本科生的发展，并通过让本科生和研究生参与基于实地的数据收集和分析程序，将他们纳入研究过程，从而建立STEM能力。研究人员将研究利用单位水流功率的纵向变化和水流梯度指数（SGI）作为泥沙通量河段尺度变化的潜在指标，以确定未来易受洪水影响的地点。利用最先进的测绘技术，包括全球定位系统（GPS）、无人机（uav）和光探测和测距（LiDAR），研究人员将绘制和测量河道调整，以测试理论、解释模式，并开发河流侵蚀和沉积的预测模型。现代测绘技术将有助于识别、定位和识别航道和洪泛平原变化的模式，而无人机将获取低空航空图像，这些图像将与“运动结构”（SfM）摄影测量技术一起使用，以开发选定地点的高分辨率、大规模地图。通过这些方法测量的侵蚀和沉积的空间格局将与通过分析水流功率预测的格局进行比较，以检验基于临界功率持续时间和水流功率空间变化的理论。提高预测河道侵蚀和沉积以及随后洪水阶段变化的能力具有巨大的社会经济影响，将有助于指导今后的防洪工作。

NATIONAL SCIENCE FOUNDATIONGEOGRAPHY SPATIAL SCIENCES (GSS) PROGRAMABSTRACT1615154Allan JamesJohn KupferUniversity of South CarolinaThis rapid-response research project will delineate and quantify the effects of large floods that occurred in early October 2015 on numerous rivers and streams in South Carolina. Extreme flooding generates considerable erosion and sedimentation and provides an excellent opportunity to study how a severe flood can modify channels and floodplains. The ephemeral data collected soon after the flooding ended will improve basic understanding of sediment transport and deposition dynamics during these large, rare floods as well as their importance in the sedimentary record. In particular, the duration of stream power above a threshold value will help predict where and how much bank and floodplain erosion will occur and when the rates of change in stream power will coincide with patterns of sedimentation. Project findings will enhance basic understanding of the magnitude and nature of geomorphic adjustments to large floods. They will help guide policy makers at city, county, state and federal levels and at local watershed associations, and they will enable research scientists to develop more effective watershed management plans for urban streams. The project also will guide the development of graduate and undergraduate students from underrepresented groups in science and engineering and will build STEM capacity by incorporating undergraduate and graduate students into the research process through their involvement in field-based data collection and analytical procedures.The researchers will investigate the use of longitudinal variations in unit stream power and stream gradient index (SGI) as potential indicators for reach-scale changes in sediment flux that identify sites that are vulnerable to future flooding. Using state-of-the-art mapping techniques including global positioning systems (GPS), unmanned aerial vehicles (UAVs), and light detection and ranging (LiDAR), the investigators will map and measure channel adjustments to test theories, explain patterns, and develop predictive models of river erosion and sedimentation. While modern mapping technologies will help identify, locate, and recognize patterns of channel and floodplain change, UAVs will acquire low-altitude aerial imagery, which will be used with "structure-from-motion" (SfM) photogrammetric techniques to develop high-resolution, large-scale maps of selected sites. Spatial patterns of erosion and sedimentation measured by these methods will be compared with patterns predicted by analysis of stream power to test theories based on the duration of critical power and spatial changes in stream power. Improvement in the ability to predict channel erosion and deposition and subsequent changes in flood stages has enormous socioeconomic implications that will help guide future flood-mitigation efforts.