Collaborative Research: RUI: Investigating the role of hillslope processes in modulating topologic change of upland drainage basins.

流域边界或排水分界线控制着景观中水和沉积物的通量，并推动水生生物的进化和物种形成。在地质时期，水系分界线随着气候和构造的变化而移动。这个作品探讨了在平缓倾斜、土壤覆盖的景观和陡峭、多山、多岩石的地区之间，分界线的运动是如何不同的。具体来说，研究人员将比较土壤沿着山坡爬行的景观和主要通过山体滑坡运输的景观。他们将使用数字制图技术，土壤和沉积物特征的实地测量，以及景观演变的理论模型来研究影响分裂运动的成分。与以往的研究不同，这项工作强调的是发生在山坡上的过程。地形分析、实地测量的粒度和宇宙核素的侵蚀速率说明了非河流过程在调节流域地形变化中的作用。为了捕捉从土壤覆盖到岩石的景观中的山坡和崩塌运输机制，这项工作利用了一系列区域侵蚀率（奥扎克高原，俄勒冈海岸山脉，圣盖博山脉）的实地测量结果。除了测试划分不稳定性的现有地形指标外，本工作还寻求定量方法的改进，以更好地将陡峭景观纳入描述和预测划分不稳定性的理论框架。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Watershed boundaries, or drainage divides, control the flux of water and sediment in a landscape and drive evolution and speciation of aquatic organisms. Over geologic time, drainage divides move in response to changes in climate and tectonics. This work explores how the motion of divides differs between gently sloping, soil-mantled landscapes and steep, mountainous, rocky areas. Specifically, the researchers will compare landscapes where soil creeps along hillslopes with those where material is primarily transported through landslides. They will use digital mapping techniques, field measurements of soil and sediment characteristics, and theoretical models of landscape evolution to investigate the ingredients that affect divide motion. Unlike previous research, which focuses on river channels, this work emphasizes processes that occur on hillslopes. Topographic analysis, field measurements of grain size, and erosion rates from cosmogenic nuclides illustrate the role of non-fluvial processes in modulating topographic change of drainage basins. To capture hillslope and colluvial transport regimes in landscapes ranging from soil-mantled to rocky, this work leverages measurements from field sites across a range of regional erosion rates (Ozark Plateau, Oregon Coast Range, San Gabriel Mountains). In addition to testing existing topographic metrics for divide instability, this work seeks quantitative methodological improvements to better incorporate steep landscapes into theoretical frameworks that describe and predict divide instability.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.