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上镜性质。山区在维持主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，如山崩和洪水。此外，山脉是新鲜岩石暴露于水和大气的地方，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被孤立地研究。该项目将在一个综合研究奋进范围内研究岩石的物理和化学变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地形到北部的高山。将采用记录地貌变化的性质和速度的尖端技术来确定山脉在地球系统中的作用。将建立模型，说明所有这些过程如何相互作用以及它们产生的影响，以预测未来的变化，并将结果应用于其他区域。这项研究将涉及多名研究生和本科生研究人员的培训，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巨大的山脉，产生了破坏性的自然灾害以及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进行多学科调查：（1）在构造活跃的山脉中，岩石在剥露过程中如何发生物理和化学变化;（2）活跃造山带的陡峭山地地形如何形成，特别是对滑坡的作用;（3）水如何从降水中通过地下进入排出活跃造山带的溪流和河流;以及（4）化学风化如何取决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，一个明显的从南到北的折返率梯度提供了一个理想的机会，记录系统层面的构造，地形演变，侵蚀，水文和化学风化之间的关系在碰撞构造的原型设置。该研究将（1）通过地球物理成像、钻孔和岩石测试等手段，表征从微米到千米尺度的岩体特征;（2）通过地下水测年、河流和泉水监测以及反应性运输建模，量化水的过境时间和化学风化反应和通量;及（3）发展景观演化模型，以解释规管山泥倾泻的相互关连过程，而山泥倾泻是这些环境下山坡侵蚀的主要工具。该项目包括学生教育的各种机会，国际合作的发展。为早期职业研究人员开设的暑期学校将扩大教育范围，并将在加德满都举办一个关于主动源地震学的短期课程，以扩大尼泊尔科学家的培训机会。该奖项反映了NSF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.