| 项目编号: | 1545623
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| 项目名称: | Impact of Changing Flood Frequency on Sediment Connectivity Between River Channels and their Riparian Margins |
| 作者: | Carl Renshaw
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| 承担单位: | Dartmouth College
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| 批准年: | 2016
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| 开始日期: | 2016-02-15
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| 结束日期: | 2019-01-31
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| 资助金额: | 466543
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| 资助来源: | US-NSF
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| 项目类别: | Continuing grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Earth Sciences
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| 英文关键词: | sediment
; floodplain
; margin
; frequency
; river restoration
; connecticut river
; fine-grained sediment source
; fine sediment connectivity
; floodplain sediment
; riparian ecology
; possible impact
; riparian ecosystem
; stream-floodplain exchange
; net channel bed-to-margin sediment flux
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| 英文摘要: | In healthy streams there is an extensive and on-going exchange of nutrients and sediment between the stream and its floodplain. As a result, re-establishing this exchange is often a primary focus of river restoration. Even in healthy streams, expected changes in the frequency and magnitude of extreme precipitation events, coupled with changes in land use, may alter the exchange of nutrients and sediment between the stream and the floodplain, possibly altering riparian ecology by changing the balance of nutrient exchanges between a channel and its margins. If the floodplain sediments are contaminated, alterations of stream-floodplain exchanges may results in the export of contaminants previously sequestered on floodplains to downstream estuaries and terminal lakes. The objective of this project is to better understand the hydrologic controls on the exchange of sediment between streams and their floodplains so that we can predict and prepare for possible impacts of climate change on riparian ecosystems. In addition, we will build on an outreach project developed as part of an NSF-sponsored linking graduate students with K-12 science classrooms. The graduate student supported by this project will work with a local middle school teacher from an under-resource rural district to develop an inquiry-based project designed to increase students' understanding of, and interest in, hydrology and water resources.
Using a recently-developed methodology that combines measurements of the fallout radionuclides 7Be and 210Pb and the stable isotopes of hydrogen (2H) in water to quantify fine sediment connectivity during individual storm events, the investigators propose to repeatedly assess fine-grained sediment sources and the factors controlling the magnitude and direction of net channel bed-to-margin sediment flux in a gravel-bedded tributary of the Connecticut River (USA). Given sufficient discharge to mobilize suspended sediment, the investigators hypothesize that there exists a critical discharge, below which the net transfer of suspended sediment is from the bed to the margins, and above which, the net transfer is from the margins to the bed or out of the watershed. The investigators seek to determine the seasonality of this critical discharge and the sensitivity of the net transfer of suspended sediment to departure from the critical discharge. They expect that currently in natural systems net deposition onto the floodplain during discharges less than the critical value is balanced by net erosion from the floodplain during high discharge events. Thus, an increase in the frequency of extreme precipitation events could result in an overall net erosion of sediment, nutrients, and particle-bound contaminants from the floodplain. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/92872
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
Carl Renshaw. Impact of Changing Flood Frequency on Sediment Connectivity Between River Channels and their Riparian Margins. 2016-01-01.
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