Long-Term Mobility and Storage of Sediments in Watersheds ofthe Upper Mississippi Valley

这项研究的总体目标是量化物理过程，这些过程影响将泥沙从源头侵蚀并最终从密西西比河谷上游流域清除的联系、路径和时间常数。将在三个时间尺度上研究流域泥沙迁移和储存对环境变化的响应，包括：历史、全新世(冰期后)和威斯康星州晚期(冰后期)。研究结果有助于更好地理解在不同时间和空间尺度上运行的环境变化如何影响湿润气候地区流域中不同位置储存或运输的泥沙类型。方法包括：(1)堆积层、冲积扇、阶地和泛滥平原沉积物的野外地层学研究；(2)实验室沉积学和地球化学分析；(3)将气候、河流径流和土地利用的档案数据与野外地层学和实验室结果联系起来的统计分析。研究应提供关键信息，以检验以下假设：流域中泥沙的侵蚀、储存和输送是一个间歇性过程，取决于影响泥沙稳定阈值的特定事件的发生。

The general objective of this research is to quantify the physical processes that influence the linkages, pathways, and time constants that separate erosion of sediment at its source and its ultimate removal from watersheds of the Upper Mississippi Valley. Responses of sediment mobility and storage to environmental changes in watersheds will be examined on three time scales, including: historical, Holocene (post- glacial), and late-Wisconsin (late-glacial). Results of the research contribute to improving the understanding of how environmental changes, operating at differing time and spatial scales, influence the type of quantity of sediment that is either stored or transported at various locations in watersheds of a humid climate region. Methodology includes: (1) field stratigraphic studies of sediment stored as colluvium, alluvial fan, terrace, and floodplain deposits, (2) laboratory sedimentological and geochemical analyses, and (3) statistical analyses that link archival data on climate, stream runoff, and land use to the field stratigraphic and laboratory results. The research should provide critical information that tests the hypothesis that erosion, storage, and delivery of sediment in watersheds is an episodic process that is dependent upon the occurrence of specific events which influence thresholds of sediment stability.