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

流域边界或排水分水岭控制着地貌中的水和泥沙的流动，并推动水生生物的进化和物种形成。随着地质时间的推移，排水分水岭会随着气候和构造的变化而变化。这项工作探索了缓坡、土壤覆盖的景观和陡峭、多山、多岩石的地区之间的分水岭运动有何不同。具体地说，研究人员将比较土壤沿着山坡爬行的景观和物质主要通过山体滑坡运输的景观。他们将使用数字测绘技术、土壤和沉积物特性的现场测量以及景观演变的理论模型来调查影响分水岭运动的因素。与以前侧重于河道的研究不同，这项研究强调了发生在山坡上的过程。地形分析、实地测量的颗粒大小和宇宙成因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覆盖的各种景观中的山坡和堆积运移机制，这项工作利用了来自不同区域侵蚀速率范围(奥扎克高原、俄勒冈海岸山脉、圣加布里埃尔山脉)的野外站点的测量结果。除了测试现有的分水岭不稳定性的地形指标外，这项工作还寻求量化方法的改进，以更好地将陡峭的地貌纳入描述和预测分水岭不稳定性的理论框架。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.