Collaborative Research: Deciphering connections among land management, soil erosion, and sediment yield in large river basins

阿曼达·施密特，保罗·比尔曼，迪伦·鲁德柏林学院，佛蒙特大学，加州大学？该项目将结合每日的产沙量记录和同位素清单来破译青藏高原4条大河的土地利用、土壤侵蚀和产沙量之间的联系。44个站点每天测量的产沙量数据，每个站点都有长达27年的每日泥沙浓度和流量记录，表明在这些流域，尽管有大量的、有充分记录的土地清理，但产沙量没有随着时间的推移而系统地增加。研究人员将把沉积物产量数据与3种同位素系统的分析结合起来，以了解为什么30年的大面积砍伐没有改变沉积物产量。他们的同位素分析将记录沉积物的来源、汇和移动速度。他们将使用一个同位素系统，在原地10Be，计算千年时间尺度上的综合背景侵蚀率；可以与现代产沙量数据进行比较的速率。第二种同位素系统，陨星10Be，将是来自受严重干扰和受较少干扰地区的沉积物混合的示踪剂，并且还可以与沉积物产量相结合，以估计土壤损失。第三种同位素系统，137Cs和210Pb，将使研究人员能够确定运输中的沉积物有多少来自深沟/滑坡侵蚀，有多少来自近地表沉积物来源。该项目将提供可与现代产沙量数据进行比较的背景侵蚀率。此外，这项工作将提供一种强有力的方法来确定受到严重干扰并正在失去土壤的子流域，即使大部分土壤没有进入河网。在实地和通过遥感进行的地貌测绘将确定在地形上以崩积层和阶地形式储存的侵蚀沉积物的位置和数量。该项目将提供关于土地利用如何在不同时空尺度上影响土壤侵蚀和产沙量的信息，这是在世界各地山区实施有意义的土地利用政策的关键数据。中国政府正在研究区域修建一系列水坝，这里是近20亿人口的淡水来源。了解沉积物从斜坡转移到河道和下游的时间尺度，对于确定这些和世界各地山区其他水坝的寿命至关重要。该项目将汇集一名杰出本科院校的早期职业教师，一名指导最先进研究设施的高级研究员，以及一名研究机构的早期职业科学家，以最大限度地丰富本科科学教育和博士生的教学培训。

Amanda Schmidt, Paul Bierman, Dylan RoodOberlin College, University of Vermont, University of California ? Santa BarbaraThis project will combine a daily record of sediment yield with isotopic inventories to decipher the connections among land use, soil erosion, and sediment yield in 4 large rivers draining the Tibetan Plateau. Sediment yield data, measured daily for 44 stations, each with up to 27 years of daily sediment concentration and discharge records, suggest that in these basins there is no systematic increase in sediment yield over time despite significant, and well-documented, land clearance. The investigators will combine the sediment yield data with analysis of 3 isotopic systems to understand why 30 years of extensive deforestation did not change sediment yield. Their isotopic analyses will document sediment sources, sinks, and rates of movement. They will use one isotopic system, in situ 10Be, to calculate background erosion rates integrated over millennial timescales; rates that can be compared to modern sediment yield data. A second isotopic system, meteoric 10Be, will be a tracer for sediment mixing from heavily disturbed and less-disturbed regions, and can additionally be combined with sediment yields to estimate soil loss. The third isotopic system, 137Cs and 210Pb, will allow investigators to determine how much sediment in transport comes from deep gully/landslide erosion and how much comes from near surface sediment sources. This project will provide background erosion rates that can be compared to modern sediment yield data. Furthermore, the work will provide a robust means of identifying sub-basins that are heavily disturbed and are losing soil, even if much of that soil is not making it into the river network. Geomorphic mapping, both in the field and through remote sensing, will determine where and how much eroded sediment is stored on the landscape as colluvium and in terraces. This project will provide information about how land-use affects soil erosion and sediment yield at different spatial and temporal scales, critical data for implementing meaningful land-use policies in mountainous regions around the world. The Chinese government is building a series of dams in the study area, the source of fresh water for nearly 2 billion people. Understanding the time scales over which sediment moves off slopes, into channels, and downstream is critical for determining the life span of these and other dams in mountainous areas worldwide. This project will bring together an early career faculty member at an exceptional undergraduate institution, a senior researcher who directs a state-of-the-art research facility, and an early career scientist at a research facility in order to achieve maximum enrichment of both undergraduate science education and pedagogical training for the doctoral students.