NSFGEO-NERC Collaborative Research: Coupling Erosion, Weathering, and Hydrologic Function in an Active Orogenic System

山脉是地球表面最壮观的特征之一，但它们的重要性远远超出了它们的拍照性质。山脉在维持重要自然资源方面发挥着关键作用，例如为大量人口提供淡水。山区是许多破坏性自然灾害的发生地，如山体滑坡和洪水。此外，山脉是新鲜岩石暴露在水和大气中的地方，导致化学反应，可以改变二氧化碳和地质时期的气候。这些过程都是密切相关的，但它们在很大程度上是孤立研究的。这个项目将在一个综合研究努力的范围内研究岩石的物理和化学转化以及水和地球物质的流动。该项目将在尼泊尔喜马拉雅山脉的一个山谷中研究这些过程，那里的地形从南部较平缓的山脉变化到北部的高山。记录自然和景观变化速度的尖端技术将被应用于确定山脉在地球系统中的作用。将开发模型，说明所有这些过程如何相互作用及其产生的影响，以预测未来的变化，并将结果应用于其他地区。这项研究将涉及培训多名研究生和本科生研究人员，并将涉及来自四个国家的研究人员之间的合作。地球构造板块之间的碰撞边界产生了引人注目的山脉，这些山脉产生了破坏性的自然灾害，也产生了控制地表环境的化学和物理交换。该项目将包括对四个相互关联的问题的多学科研究：(1)在构造活跃的山脉中，岩石在挖掘过程中如何进行物理和化学转化；(2)活动造山带的陡峭山地地形如何发育，特别是对滑坡的作用；(3)水是如何从降水中经过地下进入流经活动造山带的溪流和河流的；(4)化学风化作用如何依赖于这些环境中的构造和气候条件。该项目将调查尼泊尔中部的Melamchi Khola山谷，在那里，从南到北的挖掘速度明显呈梯度，为在碰撞构造的原型环境中记录构造、地形演化、侵蚀、水文和化学风化之间的系统级关系提供了理想的机会。该研究将(1)通过地球物理成像、钻孔和岩石测试，对从微米到公里的尺度上的岩体进行表征；(2)通过地下水测年、河流和泉水监测以及反应输运模型，量化水的传输时间和化学风化反应和通量；(3)建立景观演变模型，解释调节山体滑坡的相互关联过程，山体滑坡是这些环境下山坡侵蚀的主要载体。该项目包括多样化的学生教育机会，发展国际合作。一个面向早期职业科学家的暑期学校将扩大教育范围，一个关于活源地震学的短期课程将在加德满都举行，以扩大尼泊尔科学家的培训机会。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。

Mountain ranges are some of the most spectacular features of the Earth’s surface, but their importance extends far beyond their photogenic nature. Mountains play critical roles in sustaining key natural resources, such as supplying fresh water to large human populations. Mountainous regions are the site of many destructive natural hazards, such as landslides and floods. In addition, mountains are where fresh rocks are exposed to water and the atmosphere, resulting in chemical reactions that can modify carbon dioxide and climate over geologic time. These processes are all closely interconnected, yet they have been largely studied in isolation. This project will examine the physical and chemical transformation of rock together with the flow of water and Earth materials within the scope of one integrated research endeavor. The project will examine these processes in a valley in the Himalaya Mountains of Nepal where topography changes from more subdued in the south to high mountains in the north. Cutting-edge techniques for documenting the nature and rate of landscape change will be applied to determine the role of mountains in the Earth system. Models that illustrate how all these processes interact and the effects they produce will be developed to forecast future changes and apply the results to other regions. The research will involve training of multiple graduate and undergraduate researchers and will involve collaboration among researchers from four countries. The collisional boundaries between Earth’s tectonic plates produce dramatic mountain ranges that generate destructive natural hazards as well as chemical and physical exchanges that control the surface environment. This project will comprise a multi-disciplinary investigation of four interrelated problems: (1) how rock is transformed physically and chemically during exhumation in tectonically-active mountains; (2) how the steep mountainous topography of active orogens develops, and particularly what the role is for landslides; (3) how water makes its way from precipitation, through the subsurface, and into streams and rivers draining active orogens; and (4) how chemical weathering depends on tectonic and climatic conditions in these settings. The project will investigate the Melamchi Khola valley in central Nepal, where a pronounced south-to-north gradient in exhumation rate offers an ideal opportunity to document system-level relationships among tectonics, topographic evolution, erosion, hydrology, and chemical weathering in an archetypal setting of collisional tectonics. The research will (1) characterize rock mass across scales from the micron to kilometer, including via geophysical imaging, borehole drilling, and rock testing; (2) quantify water transit times and chemical weathering reactions and fluxes, via groundwater dating, stream and spring monitoring, and reactive transport modeling; and (3) develop models of landscape evolution that account for the interconnected processes that regulate landslides, which are the primary vehicles for hillslope erosion in these settings. The project includes diverse opportunities for student education, development of international collaboration. A summer school for early-career researchers will expand the educational reach, and a short course on active source seismology will be held in Kathmandu to broaden the training opportunities for Nepali scientists.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.