EAR-PF: The impact of varying sediment supply on Arctic delta-front transport processes

EAR-PF：不同沉积物供应对北极三角洲前缘输送过程的影响

• 批准号: 1952815
• 负责人: Brandee Carlson
• 金额: $ 17.4万
• 依托单位: Carlson, Brandee Nicole
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1952815&HistoricalAwards=false
• 关键词: EAR; PF; impact; varying; sediment

An NSF EAR Postdoctoral Fellowship has been awarded to Dr. Brandee N. Carlson to carry out research and education activities under the mentorship of Dr. Irina Overeem at the University of Colorado, Boulder. The project seeks to assess how enhanced sediment supply from melting ice sheets and glaciers, and thawing permafrost impacts the growth of Arctic deltas. The sand delivered to Arctic deltas, particularly those in West Greenland, is recognized as a potential resource for coastal restoration efforts and for industrial use (primarily concrete production) worldwide. This project will investigate the processes that control sediment retention along Arctic coastlines using field observations and remote sensing. This work will inform policy and economic decisions for sand-use in Greenland. Furthermore, the information gained from this project will be used to develop a learning module geared toward introductory undergraduate students that allows the user to explore controls on delta growth. The model will be housed at SedEdu, which is a suite of educational tools related to geomorphology and sedimentology.Subaqueous delta-front sediment transport processes are an important control on coastal evolution. Rivers and subaqueous density flows are the largest mechanisms for sediment redistribution on Earth's surface. Subaerial coastal evolution is easily-observable through historical and satellite imagery, however quantifying subaqueous sediment movement is inherently difficult because it typically requires observation in the field. Delta-front sediment transport processes become especially important to consider for rapidly growing deltas with high sedimentation rates. Under warming climate conditions, Arctic deltas, particularly those in Greenland, are rapidly growing as they receive enhanced sediment supply from melting and retreating glaciers and thawing permafrost. While there is evidence for delta-front failures that transport substantial volumes of sediment, it is unclear to what degree they influence delta progradation rates and sediment retention along coastlines. This study links readily observable data (images of subaerial delta activity) to subaqueous sediment transport processes. The objectives of this study are to determine how subaerial delta activity links to sediment transport at the subaqueous delta front and how enhanced sediment supply impacts marine sediment transport processes on Arctic deltas. In turn, the influence of delta-front failures on delta topset dynamics will be evaluated. These questions will be addressed over different temporal and spatial scales. Dr. Carlson will evaluate individual delta-front transport events at one field location during variable discharge conditions, using repeat bathymetric data. During this field campaign, changes in the subaerial delta topset (e.g. wetted area) will be evaluated using satellite imagery. Correlations between delta topset activity and delta-front transport timing/location will be used to infer relationships under past conditions (evaluated using 34 years of Landsat data) and to consider delta-front sediment transport under future conditions (e.g. how do Arctic delta-front failures vary under higher water and sediment discharge conditions in a waring climate?). These findings may offer insight into the conditions and potential effects of shifting sediment delivery for other fjord deltas in Greenland. The Geomorphology and Land-use Dynamics program in the Earth science division is co-funding this fellowship.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.

Brandee N. Carlson 博士获得了 NSF EAR 博士后奖学金，以在科罗拉多大学博尔德分校的 Irina Overeem 博士的指导下开展研究和教育活动。该项目旨在评估冰盖和冰川融化以及永久冻土融化带来的沉积物供应增加如何影响北极三角洲的增长。运送到北极三角洲，特别是西格陵兰三角洲的沙子被认为是全球沿海恢复工作和工业用途（主要是混凝土生产）的潜在资源。该项目将利用实地观测和遥感研究控制北极海岸线沉积物滞留的过程。这项工作将为格陵兰岛沙子利用的政策和经济决策提供信息。此外，从该项目中获得的信息将用于开发一个面向入门本科生的学习模块，允许用户探索对增量增长的控制。该模型将安装在 SedEdu 中，这是一套与地貌学和沉积学相关的教育工具。水下三角洲前缘沉积物输送过程是对海岸演化的重要控制。河流和水下密度流是地球表面沉积物重新分布的最大机制。通过历史和卫星图像可以轻松观察到水下海岸演化，但量化水下沉积物运动本质上很困难，因为它通常需要在现场观察。对于沉积率高、快速增长的三角洲来说，三角洲前缘的沉积物输送过程变得尤为重要。在气候变暖的条件下，北极三角洲，特别是格陵兰岛的三角洲，正在迅速增长，因为它们从冰川融化和退缩以及永久冻土融化中获得了更多的沉积物供应。虽然有证据表明三角洲前缘失稳会输送大量沉积物，但尚不清楚它们在多大程度上影响三角洲进积速率和沿海岸线的沉积物滞留。这项研究将易于观测的数据（陆上三角洲活动的图像）与水下沉积物输送过程联系起来。本研究的目的是确定陆上三角洲活动如何与水下三角洲前缘的沉积物输送联系起来，以及沉积物供应的增加如何影响北极三角洲的海洋沉积物输送过程。反过来，将评估三角洲前缘故障对三角洲顶组动力学的影响。这些问题将在不同的时间和空间尺度上得到解决。卡尔森博士将使用重复的测深数据，评估可变流量条件下某一现场位置的单个三角洲前移事件。在这次实地活动期间，将使用卫星图像评估空中三角洲顶流（例如湿润区域）的变化。三角洲顶流活动与三角洲前缘输送时间/位置之间的相关性将用于推断过去条件下的关系（使用 34 年的陆地卫星数据进行评估），并考虑未来条件下的三角洲前缘沉积物输送（例如，北极三角洲前缘如何在气候变暖的较高水和沉积物排放条件下，故障会有所不同吗？）。这些发现可能有助于了解格陵兰岛其他峡湾三角洲沉积物输送转移的条件和潜在影响。地球科学部门的地貌学和土地利用动力学项目共同资助该奖学金。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。