RAPID: Characterizing Sediment Mobilization and Landscape Response to the Combined Effects of Wildfire and Extreme Flooding along Fourmile Canyon, Front Range Colorado

这一快速项目重点关注2013年9月异常降雨事件后洪水和侵蚀对科罗拉多州前线范围内四英里峡谷的影响。该集水区仍在对2010年的一场25平方公里的野火做出反应，该小组将检验这样的假设，即2013年的洪水重新加工并沉积了最初被早期火灾动员的沉积物。该小组将研究2013年的洪水沉积、侵蚀的山坡、边支流和沟壑沉积，以及峡谷沿线新露出的梯田下的沉积。他们将重新考察作为正在进行的火灾后研究的一部分的地点，并将使用这些沉积物中的短期放射性沉降物(7Be、137Cs和210Pb)来帮助识别可再动员的火灾沉积物。此外，他们将分析山谷沉积的地球化学和地层学，并将短期野火和洪水相关侵蚀的措施与记录过去10,000-30,000年来侵蚀速率和山坡过程的正在进行的研究进行比较。在2013年9月洪水期间形成的沉积物沉积和暴露必须尽快进行采样和研究，然后随着道路重建、河道治理和景观恢复的进行，它们才能退化和消失。这些新的暴露极大地提高了使用14C分析和测定全新世斜坡和山谷地层学的能力。这项工作将加强对野火和大规模洪水增加对景观和生活在那里的人的影响的了解。因此，项目成果将为减灾和复原力提供信息。该团队将利用与USGS科学家和Boulder Creek临界区天文台的现有合作，并将直接涉及本科生和一名研究生。

This RAPID project focuses on the impacts of flooding and erosion on Fourmile Canyon in the Colorado Front Range following the exceptional September 2013 rainfall event. The catchment is still responding to a 25 km2 wildfire in 2010 and the team will test the hypothesis that the 2013 flood reworked and deposited sediments initially mobilized by the earlier fires. The team will study the 2013 flood deposits, eroded hillslopes, side-tributary and gully deposits, and deposits freshly exposed beneath terraces along the canyon. They will revisit locations that have been part of an ongoing post-fire study, and will use short-lived fallout radionuclides (7Be, 137Cs, and 210Pb) in these deposits to help identify remobilized fire sediments. In addition, they will analyze the geochemistry and stratigraphy of valley deposits and compare measures of short-term wildfire and flooding-related erosion with ongoing studies documenting erosion rates and hillslope processes over the past 10,000-30,000 years. Sediment deposits and exposures that formed during the September 2013 flooding must be sampled and studied soon, before they degrade and disappear as road rebuilding, channel manipulation, and landscape recovery proceeds. These new exposures greatly increase the ability to analyze and date Holocene slope and valley stratigraphy using 14C. The work will enhance understanding of consequences of increased incidence of wildfires and large-magnitude floods on the landscape and those who live there. As such, the project outcomes will inform hazard mitigation and resilience. The team will leverage existing collaborations with USGS scientists and the Boulder Creek Critical Zone Observatory, and will directly involve undergraduates and a graduate student.