Controls on ridgeline profile morphology

山体滑坡、泥石流和河流洪水等自然灾害威胁着生命和基础设施。地质学家和地质工程师的工作是确定容易发生自然灾害的地区，并预测灾害何时发生，从而改善公共安全。然而，这项工作需要基于物理的理解景观是如何侵蚀和进化的。地质学家花了一个多世纪的时间研究河流和山坡的侵蚀，但令人惊讶的是，在所有的景观中都存在一个迄今为止几乎没有研究过的地形特征。这些目前未被描述的地形特征是山脊线——沿着分隔两个相邻流域的地形分界线的高程剖面。目前缺乏对山脊线如何形成和侵蚀的理解，限制了对景观起伏分布（即景观的陡峭度如何变化）的预测，而景观起伏分布是预测滑坡、泥石流发生、河流泥沙通量等的关键。该方案旨在了解形成山脊线形状的过程。实现这一目标将通过提高我们对景观形成方式的理解来推进基础科学，并且还可以提高预测自然灾害的能力。除了这些好处之外，该项目还包括对未来中学教师进行基础地球科学培训。了解地球科学可以帮助学生理解气候变化等社会威胁。许多中学教师缺乏地球科学培训；为未来的教师提供这种培训，可以提高未来学生的地球科学教育质量。具体来说，这个项目将修改和增加现有的理论来描述山脊线的形状。这项工作将测试三种假设，即对山脊斜率的控制，山脊沿线的局部峰和鞍的存在，以及山脊“口”的形式（山脊向下与河流出口相遇的部分）。每个假设都将根据来自自然景观的实地数据和在受控条件下进化的预先存在的实验室实验的组合进行测试。该项目的未来教师培训部分包括为期12周的专业发展课程。未来的教师（从内华达大学里诺分校的一个培训项目中招聘）将获得900美元的津贴，并将学习适合中学教学的基本地球科学概念，并有机会制定地球科学课程计划，并在当地中学讲授这些课程。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。

Natural hazards such as landslides, debris flows, and river flooding threaten lives and infrastructure. Geologists and geological engineers work to identify areas prone to natural hazards and predict when hazards will occur, thereby improving public safety. However, this work requires a physics-based understanding of how landscapes erode and evolve. Geologists have spent over a century studying river and hillslope erosion, but, surprisingly, there is a topographic feature present in all landscapes that has seen almost no study to date. These currently undescribed topographic features are ridgelines – the elevation profile along a topographic divide separating two adjacent watersheds. The current lack of understanding of how ridgelines are shaped and eroded limits predictions of the distribution of landscape relief (i.e., how the steepness of landscapes varies), which is key to predict landsliding, debris flow occurrence, river sediment flux and more. This proposal seeks to understand the processes that set ridgeline shape. Accomplishing this will advance basic science by improving our understanding of how landscapes are formed, and can also lead to improvements in predicting natural hazards. Beyond these benefits, the project includes training for future middle school teachers in basic earth science. Understanding earth science can help students contextualize and understand societal threats such as climate change. Many middle school teachers lack earth science training; providing this training to future teachers can improve the quality of geoscience education for future students. Specifically, this project will modify and add to existing theory to describe the shape of ridgelines. The work will test three hypotheses about the controls on ridgeline slope, the presence of local peaks and saddles along ridgelines, and the form of ridgeline ‘snouts’ (the portion where the ridge dives down to meet the river outlet). Each hypothesis will be tested against a combination of field data from natural landscapes and pre-existing laboratory experiments where landscapes are evolved under controlled conditions. The future teacher training portion of the project consists of a 12-week long professional development course. Future teachers (recruited from a training program at the University of Nevada Reno) will earn $900 stipends and will be taught basic geoscience concepts appropriate for middle school teaching and have the opportunity to develop geoscience lesson plans and present these lessons in local middle schools.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.