Collaborative Research: Timescales and drivers of floodplain disequilibrium at climatic transitions

合作研究：气候转变时洪泛区不平衡的时间尺度和驱动因素

• 批准号: 2114771
• 负责人: Isaac Larsen
• 金额: $ 7.84万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2114771&HistoricalAwards=false
• 关键词: Collaborative; Research; Timescales; drivers; floodplain

Rivers and floodplains significantly influence the landscapes and environments through which they pass. These systems exhibit a range of forms and characteristics (morphologies) controlled by a balance between the availability of unconsolidated rock (sediment) and the river’s capacity to transport that sediment. As climate exerts a major control on these variables, floodplain morphologies are expected to undergo major changes as Earth’s climate warms. Under a warming climate, sediment supply often declines relative to transport capacity and narrowing floodplains are characterized by vertical cutting through older deposits creating stair-stepped landscape features called river terraces. The goal of this study is to deepen our understanding of how floodplains have responded to different magnitudes and timescales of climatic changes in the past to enhance our ability to predict the extent to which they will change in the future. This goal will be achieved by determining the timing of river terrace formation and comparing it to known climate shifts throughout Earth’s recent geological past. The project also supports a summer workshop on landscape evolution for middle school girls from historically underrepresented groups, the development of an accessible undergraduate virtual field project on terrace formation, and the facilitation of a community field workshop to share project results.Specific research questions include: (1) What duration and intensity of climatic change is required to drive significant changes to floodplain morphology? (2) How long does it take for floodplains to establish new, stable morphologies after significant climate-driven changes? (3) To what extent do non-climatic mechanisms counter or enhance climatic controls on floodplain processes? These questions will be addressed by resolving the timing of ~14,000 years of floodplain aggradation and degradation preserved in river terraces in eastern Scotland and comparing them against the timing of major and minor climatic transitions and glaciations. Eastern Scotland is an ideal location to undertake this work because it is tectonically inactive, has an excellent climate chronology, has undergone both continental ice sheet and alpine glaciation, and contains river terrace successions. The terrace chronology will be developed using radiocarbon, optically stimulated luminescence, and cosmogenic nuclide exposure dating. A comparison of the timing and duration of river morphology changes between field sites with the same climatic and glacial history, but with different catchment properties, will be undertaken to determine how non-climatic variables influence aggradation and degradation cycles. The research will also address the role of prior glacial erosion on influencing floodplain morphology and modern sediment routing.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.

河流和洪泛区极大地影响了它们经过的景观和环境。这些系统表现出一系列形式和特征（形态），这些形式和特征（形态）通过未固结岩石（沉积物）的可用性与河流运输沉积物的能力之间的平衡控制。随着气候对这些变量产生重大控制，随着地球的气候温暖，洪泛区形态有望发生重大变化。在温暖的气候下，相对于运输能力和狭窄洪泛区的沉积物供应经常下降，其特征是通过较旧的沉积物进行垂直切割，从而产生了楼梯稳步的景观特征，称为河流露台。这项研究的目的是加深我们对洪泛区如何响应过去慢性变化的不同尺寸和时间表的理解，以增强我们预测未来其将来会改变的程度的能力。河露台形成的时机，并将其与广泛地球最近的地质历史进行比较。该项目还支持有关历史上代表性不足的群体的中学女孩的夏季研讨会，开发露台形成的本科本科虚拟现场项目的发展以及社区实地研讨会的设施共享项目结果。具体的研究问题。具体的研究问题包括：（1）（1）文明变化的持续时间和强度对泛滥的变化需要泛滥的变化，以驱动洪水泛滥的变化？ （2）在重大气候驱动的变化之后，洪泛区建立新的，稳定的形态需要多长时间？ （3）非气候机制在多大程度上应对或增强洪泛区过程中的杂志控制？这些问题将通过解决约14，000年的洪泛区聚集和退化的时间来解决，并将其与苏格兰东部的河流露台保存，并将其与主要和小杂交过渡和冰川的时机进行比较。苏格兰东部是从事这项工作的理想场所，因为它在构造上是不活跃的，具有出色的气候年表，既经历了连续的冰盖和高山冰川，又有河露台的演替。露台年表将使用放射性碳，光刺激的发光和宇宙核素暴露年代开发。将对具有相同气候和冰川历史的野外地点之间的时间和持续时间变化进行比较，但将采取不同的集水区特性，以确定非气候变量如何影响聚集和降解周期。这项研究还将解决先前冰川侵蚀在影响洪泛区形态和现代沉积物路由的作用。该奖项反映了NSF的法定任务，并且使用基金会的知识分子优点和更广泛的影响评估标准，被认为值得通过评估来获得支持。