Collaborative Research: Is Anthropocene sedimentation in valley bottoms a geologically significant event?

最近对地貌学的研究发现，在过去的几个世纪里，人类对美国东北部土地的改造导致了大量的沉积物从山坡上被侵蚀，并沿着河流和小溪沉积在山谷里。地貌学是研究地球表面及其形成过程的学科。先前的研究表明，这种沉积物转移是数万年来地球景观最重要的变化。该项目将在区域范围内评估这些沉积物的重要性，方法是在有代表性的实地地点仔细测量这些沉积物，然后利用新获得的高分辨率地形数据将这些发现推断到整个流域和地区。了解人类活动如何促成景观变化是明智的土地管理和恢复决策的先决条件。为了确保项目成果的广泛传播，研究人员将与政策制定者、规划者、政府机构和对河流和湿地保护感兴趣的非营利组织进行互动。该项目还将为学生研究提供强大的机会，因为合作院校在本科教育方面投入了大量资金。项目技术说明最近的全球沉积研究表明，人类活动造成的侵蚀速度超过了河流向海洋输送的泥沙量。同时，从河道到流域尺度的实地研究发现，在过去的几个世纪里，大量的沉积物储存在山谷底部。该项目将通过量化美国东北部山谷底部储存的人类世（最近的，与人类有关的）沉积物的数量，然后将这一数量与已公布的数量和时间尺度进行比较（1)景观侵蚀，(2)大西洋边缘水库、湖泊和河口沉积），从而弥合全球和基于流域的方法之间的差距。该研究将使用高分辨率地形数据在大空间区域（1,000-10,000平方公里）上绘制这种填充物的范围和厚度，并将在关键流域通过实地工作（测绘、取心、地球物理数据收集、沉积物取样和定年）对这些方法进行测试。一个中心目标是评估未冰川的中大西洋地区的沉积物储存在多大程度上适用于冰川覆盖、研究较少的新英格兰地区，那里的高地土壤很薄，沉积物来源通常局限于冰川沉积物，大型天然湖泊和湿地提供了陆地容纳空间。该项目的结果将有助于解决小空间（流域）和时间（十年至百年）尺度上的侵蚀和沉积速率与全球和地质时间内发生的速率之间的差异。

Non-technical description of the project's broader significance and importanceRecent research in geomorphology, the study of Earth's surface and the processes that shape it, has found that human modification of land in the northeastern U.S. over the past few centuries has resulted in large volumes of sediment being eroded from hillsides and deposited in valleys along rivers and streams. Prior research has suggested that this sediment transfer is the most important modification of Earth's landscape in tens of thousands of years. This project will evaluate the significance of these deposits on a regional scale by carefully measuring them in representative field locations and then using newly available high-resolution topographic data to extrapolate the findings to whole watersheds and regions. Knowledge of how human activities have contributed to landscape change is a prerequisite for informed land-management and restoration decisions. To ensure broad communication of project findings, the researchers will interact with policy makers, planners, government agencies, and non-profit organizations interested in stream and wetland conservation. This project also will include strong opportunities for student research, since the collaborating institutions are heavily invested in undergraduate education as a priority.Technical description of the project Recent global sedimentation studies demonstrate that rates of erosion due to human activities exceed the amount of sediment delivered to the oceans by rivers. At the same time, field-based studies at the channel to watershed scale have found large quantities of sediment stored in valley bottoms during the past few centuries. This project will bridge the gap between global and watershed-based approaches by quantifying the amount of Anthropocene (recent, human related) sediment stored in valley bottoms of the northeastern United States, and then comparing this amount to published volumes and timescales of (1) erosion from the landscape, and (2) deposition in reservoirs, lakes, and estuaries along the Atlantic margin. The research will use high-resolution topographic data to map the extent and thickness of this fill over large spatial areas (1,000-10,000 square km), and will test these methods using fieldwork (mapping, coring, geophysical data collection, sediment sampling and dating) in key watersheds. A central goal is to evaluate the extent to which sediment storage in the unglaciated mid-Atlantic region applies in the glaciated, less-studied New England region, where upland soils are thin, sediment sources are generally localized to glacial deposits, and large natural lakes and wetlands provide terrestrial accommodation space. The results of the project will help resolve the discrepancy between erosion and deposition rates at small spatial (watershed) and temporal (decadal to centennial) scales versus the rates that occur globally and over geological time.