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

Amanda Schmidt，Paul Bierman，Dylan RoodOberlin学院，佛蒙特州大学，加州大学？圣巴巴拉这个项目将结合每日产沙量记录和同位素清单，破译青藏高原四条大河的土地利用、土壤侵蚀和产沙量之间的关系。44个站每天测量的产沙量数据，每个站都有长达27年的每日含沙量和流量记录，表明这些盆地的产沙量并没有随着时间的推移而系统地增加，尽管有大量的、有充分记录的土地清理。研究人员将结合泥沙产量数据和3个同位素系统的分析，来理解为什么30年的大规模砍伐森林并没有改变泥沙产量。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，原位10Be，来计算千年时间尺度上的背景侵蚀速率；这些速率可以与现代的沉积物产量数据进行比较。第二个同位素系统，大气10Be，将成为来自干扰严重和干扰较少地区的沉积物混合的示踪剂，并可以另外与沉积物产量相结合，以估计土壤流失。第三个同位素系统，137Cs和210Pb，将使研究人员能够确定运输中的沉积物中有多少来自深沟/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泥沙产量数据相比较的背景侵蚀速率。此外，这项工作将提供一种强大的手段来识别受到严重干扰并正在流失的子盆地，即使这些土壤中的大部分没有进入河网。在野外和通过遥感绘制地貌图，将确定侵蚀沉积物以丘陵和梯田的形式储存在景观上的哪里以及储存了多少。该项目将提供有关土地利用如何在不同空间和时间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，该区域是近20亿人的淡水来源。了解泥沙移出斜坡、进入渠道和下游的时间尺度，对于确定这些大坝和世界各地山区其他大坝的寿命至关重要。该项目将汇集一所特殊本科机构的早期职业教员、一名领导最先进研究设施的高级研究员和一名研究设施的早期职业科学家，以实现对博士生的本科科学教育和教学培训的最大限度丰富。

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.