Collaborative Research: Watershed-scale Geomorphic Response to Climate Change in the Aklavik Range, NWT (Canada)

北极地貌对快速的人为气候变化的反应有可能从根本上改变人类和自然系统。这包括永久冻土融化和相关的斜坡不稳定增加对北极社区的危害，以及北极河流中较高的沉积物和营养物质产量对河流和沿海栖息地的破坏。虽然北极地貌显然对气候变化很敏感，但我们对温度变化将如何影响沉积物通过分水岭的输送方式的了解存在差距。为了解决这一知识差距，调查人员将对加拿大西北地区Aklavik山脉的北极流域进行实地和遥感研究，许多原住民社区位于那里。研究小组将测试这一具体假设，即北极的气候变化正在导致山区更快地产生泥沙，并导致随后向山坡和河流输送的泥沙增加。这是一个跨学科的项目，涉及三个早期职业终身教职-跟踪教师，多个当地合作者，以及Ehdiitat Gwich‘in。研究人员将沿着南北气候梯度研究两个小的基岩流域(产生沉积物的地方)及其相关的扇形沉积(储存沉积物的地方)。此前对这些扇沉积的地貌研究是在20世纪60年代至80年代进行的，这使它们成为定量评估随时间变化的理想地点。主要目标是：(1)开展实地工作，了解沉积物如何产生及其在这一地貌中的运动过程；(2)对实地收集的样本进行实验室分析，以量化十年至千年尺度上的沉积物产生和迁移速率；(3)利用遥感技术，将过去几十年来当地的研究结果推广到更广泛的区域；(4)利用这些数据来校准沉积物的产生和迁移模型，以便我们能够预测未来北极地貌对人为变暖情况的反应。许多测年和遥感技术在过去几十年里有了很大的进步，但还没有被应用于跨越整个分水岭的北极综合研究。一旦在这项研究中得到证实，这种方法组合可用于其他地貌(北极和低纬地区)，以更好地量化一种地貌过程的速率变化(例如，基岩破裂)如何影响另一种地貌过程的速率的变化(例如，向河流输送泥沙的速率)。此外，在该项目期间收集的数据将校准最新的科学模型，使科学家能够更好地向当地社区通报未来变暖带来的潜在危险。这一奖项反映了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。

Arctic landscape response to rapid anthropogenic climate change has the potential to fundamentally alter both human and natural systems. This includes increased hazards to Arctic communities from permafrost thaw and associated slope instability and the destruction of river and coastal habitats from higher sediment and nutrient yields in Arctic rivers. While it is clear that Arctic landscapes are sensitive to climate change, a gap exists in our knowledge about how changes in temperature will affect the ways in which sediment is transported across a watershed. In order to address this knowledge gap, the investigators will be conducting a field- and remote sensing-based study of Arctic watersheds in the Aklavik Range of the Northwest Territories (NWT), Canada, where numerous First Nations communities are situated. The research team will test the specific hypothesis that climate change in the Arctic is leading to faster production of sediment within mountainous regions and causing subsequent increases in sediment delivery to hillslopes and rivers. This is an interdisciplinary project that involves three Early Career tenure-track faculty, multiple local collaborators, as well as the Ehdiitat Gwich’in. The investigators will study two small bedrock watersheds (where sediment is produced) and their associated fan deposits (where sediment is stored) along a north-south climate gradient. Prior geomorphic work on these fan deposits was conducted in the 1960s to 1980s, making them an ideal location to quantitively assess change over time. The major objectives are to: (1) conduct fieldwork to understand how sediment is produced and the processes by which it moves across this landscape; (2) perform laboratory analyses on samples collected in the field to quantify rates of sediment production and transport over decadal to millennial scales; (3) use remote sensing techniques to extend local findings to the broader region over the last several decades; and (4) to use these data to calibrate sediment production and transport models so that we can predict future Arctic landscape response to anthropogenic warming scenarios. Many of the dating and remote sensing techniques have greatly advanced in the last several decades, but have not been applied to an integrated Arctic study spanning an entire watershed. Once proven in this study, this combination of methods could be used in other landscapes (both in the Arctic and at low latitudes) to better quantify how changes in rates of one geomorphic process (e.g., breakdown of bedrock) affects changes in rates of another (e.g., rates of sediment delivery to a river). In addition, the data collected during this project will calibrate state-of-the-science models allowing scientists to better inform local communities of potential hazards due to future warming.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.