Collaborative Research: Predicting riverbank erosion in thawing permafrost

大多数北极洪泛平原都有永久冻结的底土或永久冻土，这使沿海和河岸的土地保持完整，适合居住。然而，永久冻土融化会导致土地的广泛不稳定，并加剧河岸侵蚀。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。这项提议的主要目的是发展和测试永久冻土中河岸侵蚀的数学理论。这一理论将在加州理工学院的地球表面动力学实验室进行新的室内永久冻土河实验，并通过与阿拉斯加土著社区Huslia合作，沿着Koyukuk河进行测量。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，它还将有助于育空河流域河畔社区的气候变化适应规划。下一代科学家将在本科和博士阶段接受综合危害评估方面的培训，通过将社区参与与基础科学和应用科学结合起来，解决具有地方和全球影响的环境危机。本提案的主要目的是开发和测试永久冻土中河岸侵蚀的热力学模型。除了试图了解寒冷环境下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率如何响应气候变化。该模型将通过专门设计的水槽实验进行测试，以跨越永久冻土河流特征的范围，并测试与河流流速、河水温度和河岸沉积物粒度有关的假设。测量阿拉斯加Koyukuk河沿岸河岸的水力、机械和热特性，将用于评估夹带和烧蚀限制机制的模型。该项目由地貌学和土地利用动力学以及北极自然科学项目共同资助。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。

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.