Collaborative Research: Predicting riverbank erosion in thawing permafrost

大多数北极泛滥平原都有永久冻结的底土，或永久冻土，这使土地保持完好，适合海岸和河岸的居住。然而，永久冻土融化可能导致广泛的土地不稳定和加剧河岸侵蚀。这种侵蚀威胁到对国家繁荣和安全至关重要的关键基础设施，并导致整个阿拉斯加社区流离失所。这项建议的主要目的是发展和检验多年冻土中河岸侵蚀的数学理论。这一理论将通过加州理工大学地球表面动力学实验室的新型室内永久冻土河流实验，以及与阿拉斯加土著社区Huslia合作，沿着亚肯色州Koyukuk河进行测量来验证。这项工作有望填补我们对河流系统如何应对全球变暖的基本理解的空白。此外，它还将为育空河流域河滨社区的气候变化适应规划做出贡献。下一代科学家将在本科和博士级别接受综合危险评估方面的培训，方法是将社区参与和基础科学和应用科学结合起来，以解决具有地方和全球影响的环境危机。这项建议的主要目的是开发和测试多年冻土中河岸侵蚀的热力学模型。除了试图了解寒冷环境中河岸侵蚀的基本机制外，该模型还将用于定量评估河岸侵蚀速率将如何应对气候变化。该模型将针对专门设计的跨越永久冻土河流特性范围的水槽实验进行测试，并测试与河流流速、河流水温和岸边沉积物颗粒大小有关的假设。阿拉斯加Koyukuk河沿岸岩床的水力、机械和热学特性的测量将被用来评估卷吸和烧蚀限制条件下的模型。该项目由地貌学和土地利用动力学和北极自然科学计划共同资助。该奖项反映了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。

Most Arctic floodplains have permanently frozen subsoil, or permafrost, that keeps the land intact and habitable along coasts and riverbanks. However, permafrost thaw can lead to widespread destabilization of the land and enhanced riverbank erosion. This erosion threatens critical infrastructure that is vital to national prosperity and security, and has led to the displacement of entire Alaskan communities. The main objective of this proposal is to develop and test a mathematical theory for riverbank erosion in permafrost. The theory will be tested using novel indoor permafrost-river experiments at the Caltech Earth Surface Dynamics Laboratory, and through measurements along the Koyukuk River, AK, in collaboration with the Native Alaskan community of Huslia. The work promises to fill a gap in our basic understanding of how river systems respond to global warming. In addition, it will contribute to climate-change adaptation planning for riverside communities in the Yukon River watershed. The next generation of scientists will be trained at the undergraduate and PhD levels in integrated hazard assessment by bringing together community engagement and basic and applied science to address an environmental crisis with both local and global implications. The main objective of this proposal is to develop and test a thermo-mechanical model for river-bank erosion in permafrost. In addition to seeking to understand the basic mechanics of bank erosion in cold environments, the model will be used to quantitatively assess how bank erosion rates will respond to climate change. The model will be tested against flume experiments specially designed to span the range of permafrost river characteristics and to test hypotheses related to river flow velocity, river water temperature, and bank sediment grain size. Measurements of hydraulic, mechanical and thermal properties of cutbanks along the Koyukuk River, Alaska, will be used to evaluate the model for entrainment- and ablation-limited regimes. This project was jointly funded by the Geomorphology and Land-use Dynamics and Arctic Natural Sciences Programs.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.