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

对该项目更广泛意义和重要性的非技术性描述最近在地貌学、地球表面及其形成过程方面的研究发现，在过去的几个世纪里，美国东北部的人类对土地的改造导致了大量的沉积物从山坡上被侵蚀，并沉积在河流和溪流沿线的山谷中。先前的研究表明，这种沉积物的转移是数万年来地球景观最重要的改变。该项目将在区域范围内评估这些沉积物的重要性，方法是在具有代表性的野外地点仔细测量它们，然后利用新获得的高分辨率地形数据将结果外推到整个流域和区域。了解人类活动如何促成地貌变化是作出知情的土地管理和恢复决定的先决条件。为了确保项目成果的广泛沟通，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性组织进行互动。该项目的技术描述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沉淀物的数量。与此同时，从河道到分水岭尺度的实地研究发现，在过去的几个世纪里，大量的泥沙储存在河谷底部。该项目将通过量化储存在美国东北部谷底的人类世(最近的，与人类有关的)沉积物的数量，然后将这一数量与公布的(1)地形侵蚀和(2)大西洋边缘水库、湖泊和河口沉积的数量和时间进行比较，从而弥合全球方法和基于分水岭的方法之间的差距。这项研究将使用高分辨率地形数据在大片空间区域(1,000-10,000平方公里)上绘制这种填充物的范围和厚度，并将在关键流域进行野外工作(测绘、取心、地球物理数据收集、沉积物采样和测年)来测试这些方法。一个中心目标是评估大西洋中部未冰川地区的沉积物储存在冰化、研究较少的新英格兰地区的适用程度，那里的旱地土壤很薄，沉积物来源通常局限于冰川沉积，大型天然湖泊和湿地提供陆地栖息空间。该项目的成果将有助于解决小空间(分水岭)和时间(十年至百年)尺度的侵蚀和沉积速率与全球和地质时期的侵蚀和沉积速率之间的差异。

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.