| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | September 9, 2011 |
| Latest Amendment Date: | August 24, 2016 |
| Award Number: | 1124482 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Justin Lawrence
jlawrenc@nsf.gov (703)292-2425 EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | September 15, 2011 |
| End Date: | August 31, 2017 (Estimated) |
| Total Intended Award Amount: | $244,461.00 |
| Total Awarded Amount to Date: | $244,461.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
506 S WRIGHT ST URBANA IL US 61801-3620 (217)333-2187 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
506 S. Wright Street Urbana IL US 61820-3620 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Geomorphology & Land-use Dynam |
| Primary Program Source: |
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| Program Reference Code(s): | |
| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
The focus of this project is the meandering of river channels, an iconic phenomenon in geomorphology and a fundamental process of channel morphodynamics. The goal is to advance our understanding of meander morphodynamics in eroding channels enough to develop a general theoretical framework for channel meanders in a variety of environments. A particular focus is the meandering of mixed bedrock-alluvial channels and the role of sediment cover in the mediation of patterns of channel erosion. Such processes are being studied through a combination of field studies, laboratory experiments, numerical simulations and theoretical analysis. Novel aspects of the research include: (i) the study of micro-scale dissolutional meanders in the field and the laboratory as a proxy for macro-scale abrasional meanders, and (ii) the development of meander morphodynamic model whose channel cross-section is not fixed but rather evolves according to a plug-in constitutive equation for erosion rate.
Meandering streams and rivers are a vital part of the natural landscape of the United States and beyond. Over the centuries, many of these rivers have been modified drastically and their crucial environmental role compromised. Remediation of these rivers has become a priority in recent years as the negative effects of such environmental damage have become clear. For remediation to succeed, and for the assessment and management of meandering rivers to be effective, a thorough understanding of channel morphodynamics is needed. The aim of this project is to deepen such understanding and to pass on these advances to the broad community of scientists and engineers interested in the topic.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
We hereby report the outcomes of our award, " Collaborative Research: A field, laboratory and theoretical study of mixed bedrock-alluvial meandering rivers. Our outcomes fall into three parts: alluvial cover in mixed bedrock-alluvial meandering streams, hydraulic resistance in mixed bedrock-alluvial meandering streams, and meandering channels on ice surfaces.
Meandering bedrock streams resemble meandering alluvial streams in many ways, but have some key differences. Meandering bedrock streams incise downward as they migrate laterally. A common mechanism for incision or migration into bedrock is collision between alluvial stones and a bedrock surface. In order for this to occur, a transient cover of alluvium is necessary. If the alluvial cover is vanishing, there are no tools to erode the bedrock. If the bedrock is completely alluviated, stones cannot collide with it, again implying no incision. We have performed the first comprehensive set of experiments on cover in an experimental bedrock meandering channel. We show that it is the frequency of collision of stones with the bed, and not the average cover ratio, that controls potential erosion.
We also performed experiments on meandering channels incising into ice. Our experiments are the first of their kind. We reproduce self-formed meandering channels at both the centimeter and millimeter scale. We show that these meanders have many geometric properties that are similar to alluvial meandering, but also show some important differences, such as downstream skewing as opposed to upstream skewing.
Last Modified: 05/31/2018
Modified by: Gary Parker
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