| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | August 23, 2013 |
| Latest Amendment Date: | July 22, 2015 |
| Award Number: | 1324335 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Justin Lawrence
jlawrenc@nsf.gov (703)292-2425 EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | September 1, 2013 |
| End Date: | August 31, 2017 (Estimated) |
| Total Intended Award Amount: | $263,664.00 |
| Total Awarded Amount to Date: | $263,664.00 |
| Funds Obligated to Date: |
FY 2015 = $78,166.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
110 INNER CAMPUS DR AUSTIN TX US 78712-1139 (512)471-6424 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
1 University Station C9000 Austin TX US 78712-0323 |
| 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: |
01001516DB NSF RESEARCH & RELATED ACTIVIT |
| 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
Deltas are home for 25% of the human population (Syvitski et al., 2005). Across the world, combinations of changes in sea-level-rise rates, land use changes in the watersheds the feed deltas, and human activities on deltas themselves are causing rapid changes to delta landscapes and loss of valuable habitats and ecosystem services. Science for predicting changes in delta landscapes, ecosystems, and coastlines is now urgently required to successfully evaluate and implement plans to improve sustainability for deltas globally. However, changes on deltas are controlled by an array of interactions between coastal rivers, plants and animals, hurricanes and storms, and a range of human manipulations. The proposed study will enhance our understanding of, and ability to predict how deltas will respond to changes in climate and land-use forcing, focusing on both physical and biological aspects of delta systems using laboratory flume and computational experiments.
Physical delta experiments will be conducted in the University of Texas (UT) Sediment Transport and Earth-surface Processes (STEP) basin, which allows for independent and precise controls of the major geological factors: sediment supply and relative sea level rise (RSLR). These experiments will also be the first to investigate interactions between physical and biological processes in shaping deltas. Experiments will involve seeding the delta surface with small plants (Alfalfa) at different spatial densities. The ecosystem is simplified in the experiments but still naturally coevolving with a growing and self-organizing fluviodeltaic system. Computational modeling efforts, based on the results of the physical experiments, will produce a reduced complexity model that captures the main eco-morphodynamic feedbacks under rapid relative sea-level rise over engineering and geological time scales. The resulting computational models will provide a platform for experiments addressing the ecomorphodynamic evolution of a range of delta types, under disparate sets of forcing (e.g. river vs. wave dominated) and under various scenarios of land-use and climate changes. The scientific insights to be gained through the coupled laboratory experiments and computational modeling include: 1) the fluviodeltaic system's response to RSLR, in particular, changes in avulsion (flood) frequency and shoreline roughness, 2) the self-organization of the deltaic distributary channel network that coevolves with vegetation, 3) the effects of spatial variation in vegetation density on channel avulsion location and frequency, and 4) how the feedbacks from vegetation dynamics during rapid RSLR affect deltaic landforms and resulting stratigraphy. This work will produce the first quantitative eco-morphodynamic model based on controlled laboratory experiments, allowing exploration of future changes in fluviodeltaic landscapes, channel activity, and vulnerability for a range of delta types and RSLR rates.
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.
Deltas across the globe provide for the livelihoods of more than 25% of the human population. Science for predicting delta/coastline evolution is now urgently required to successfully evaluate and implement master plans for deltas around the world to restore and secure coastal sustainability. The success of coastal restoration relies partially on understanding plants. Depending on their density and growth rates, plants may promote or hinder sedimentation in deltas. To gain better insight into dynamic feedbacks between ecosystem and delta development, we used a laboratory tank experiment to study delta dynamics with growing vegetation. We supplied a mixture of water and sediment into one end of a three-meter-long basin, seeded small plants, and documented the effects of plants and flow patterns on the development of a small-scale delta. A series of experiments has been conducted over a range of plant seeding rates. Time-lapse images and topographic surface were collected during the experiments as the delta and plants coevolved. These experimental data are available through a web-based knowledge base (sedexp.net) and data repository (sead-data.net). We also coupled insight from the laboratory experiments with computational modeling. A modeling module has been developed for addressing the interactions between dynamic vegetation growth and sediment transport in the delta context. The new module is available in the Community Surface Dynamics Modeling System (CSDMS) toolbox of coupling-ready models for computational modelers free use. An experimental component for basic sedimentary geology has been incorporated into the lectures of GeoFORCE Texas, a Jackson School of Geosciences program that encourages high school students in under-represented groups to pursue rigorous math and science curricula throughout their education. Key scientific outcomes from the project can be summarized as the following: 1) Plants enhance deposition and can inhibit channelization by introducing additional surface roughness (reducing skin friction shear stress) and limiting channel incision. 2) Discharge fluctuations through flood and interflood cycles create channel relief and help to maintain unvegetated areas on the aggrading delta surface. 3) Plant patches help to increase the number of channels and make a more distributive channel network. 4) Patchiness increases over time to continually aid in river bifurcation. As the vegetation cover and patch sizes increase, patches begin to merge. The merged larger patches block the flow to enhance topset deposition and channel filling. We conclude that non-flood flow (interflood flow) and vegetation patchiness are important factors in delta evolution. Future efforts to model delta formation should incorporate discharge fluctuations and vegetation patchiness and its growth, which are often neglected in the delta modeling, but are found in nature.
Last Modified: 12/30/2017
Modified by: Wonsuck Kim
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