| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | October 16, 2017 |
| Latest Amendment Date: | October 16, 2017 |
| Award Number: | 1763088 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Deborah K. Smith
OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | November 1, 2017 |
| End Date: | October 31, 2018 (Estimated) |
| Total Intended Award Amount: | $64,644.00 |
| Total Awarded Amount to Date: | $64,644.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
4300 MARTIN LUTHER KING BLVD HOUSTON TX US 77204-3067 (713)743-5773 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
TX US 77205-2015 |
| 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): | Hurricane Harvey 2017 |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Tropical cyclones cause significant changes in coastal sediments and shorelines. While there is an understanding that storm surges are important, the effects of fresh water surges from high rainfall events are less well studied and understood. Hurricane Harvey dumped ~34 trillion gallons of rainwater on the Texas-Louisiana Gulf of Mexico coast, the most of any tropical storm in U.S. history. The Houston-Galveston area was at the bullseye of the rainfall, creating an extraordinary 11-day fresh water surge into Galveston Bay, the largest Texas estuary. Water flow volumes were so high and outflow currents so strong that sand deposits were left all along the banks of Houston's normally slow-flowing bayous (streams and rivers), indicating that large volumes of coarse sediment were mobilized by the storm, much of which likely ended up in Galveston Bay. Just weeks prior to the hurricane, The University of Houston completed geophysical sonar surveys of the two natural inlets to Galveston Bay: Bolivar Roads and San Luis Pass. These surveys gathered geophysical data that resulted in the production of high-resolution depth maps and acoustic images of the inlet floors which showed sediment types, thickness, and vertical layering and bottom features, among other things. This research repeats those surveys, post-storm, and collects sediment cores to document storm erosion and deposition at Bolivar Roads and San Luis Pass. A comparison of the pre- and post-storm surveys provides an unprecedented opportunity to learn about the erosion and sediment transport and deposition of a storm the magnitude of Hurricane Harvey. Broader impacts of the project include data and reports that will be shared with the public and relevant government agencies to aid in management and decision making because Bolivar Roads is not only one of the busiest shipping channels in the nation but is also the proposed location for the gates of a coastal barrier that has been proposed to protect Galveston Bay. Information from a comparison of the two sets of sonar surveys will be critical for planning and managing any proposed flood/storm surge structure and results of the study will be made available to the public and appropriate government and planning officials. An additional impact will be the training of students who will participate in the post-storm marine geophysical survey. Because the University of Houston has a diverse student body and is a Hispanic-serving institution, efforts will be made to engage students from minorities under-represented in the sciences.
This research repeats marine geophysical surveys (side scan, swath bathymetry, and CHIRP) at Bolivar Roads and San Luis Pass, the two major inlets to Galveston Bay in coastal Texas where identical surveys were taken just a few weeks prior to Hurricane Harvey. This repeat survey will document changes to the inlets and estuary resulting from the unprecedented rainfall event associated with Hurricane Harvey, which dumped 34 trillion gallons of rain on the Houston/Galveston area. Sediment cores from the estuary and inlets will also be collected. Results of the repeat survey and analyses of the cores will be compared to the results of the survey taken pre-storm to get a better understanding of sediment erosion and deposition and redistribution. It will also examine changes in estuary/inlet seafloor morphology. The San Luis Pass survey will use a CHIRP sonar (2-16 kHz) to image subbottom layers over a network of ~50 km of track lines near the pass because the water in this area is too shallow for swath sonars. The Bolivar Roads survey will cover a 2 x 6.5 km section of the inlet using the CHIRP sonar and a 548 kHz side-scan sonar/interferometric bathymetry instrument. Soundings from the latter system will be used to make a high-resolution bathymetry map, which will show changes in depth caused by storm erosion and deposition. This sonar also provides acoustic backscatter images of the water bottom, showing topography, sediment type, bedforms, and anthropogenic debris. A third cruise will collect ~25 gravity cores, that will be used for ground-truth of the sonar images and to look for a storm event layer. Comparison of pre- and post-storm surveys will show how the strong currents and heavy sediment loads of the rainfall surge affected the inlets. This information is important for complete coastal sedimentation models as well as for agencies tasked with coastal management, especially if the planned coastal barrier to protect Galveston is built across Bolivar Roads.
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.
The project was a RAPID grant, a project meant to collect ephemeral data after an extraordinary environmental event. The focus event was the rainfall pulse of Hurricane Harvey, which occurred on the Texas coast at the end of August 2017. The purpose of the project was to conduct sonar surveys in the two inlets to Galveston Bay, the largest estuary on the Texas coast. The two inlets are Bolivar Roads, the main inlet to Galveston Bay, which also hosts the Houston Ship Channel, a major industrial waterway, and San Luis Pass, a smaller outlet. The purpose was to examine the effect of the massive freshwater surge through the bay after Hurricane Harvey. The Bolivar Roads survey was planned to resurvey an area surveyed with sonars only three weeks before the storm. The San Luis Pass flood tide delta was already being studied by one of the investigators.
The main Bolivar Roads survey was conducted during November 2017 and it collected side-scan sonar imagery and interferometric bathymetry of the area surveyed prior to the storm. CHIRP sonar sub-bottom profile data were collected simultaneously. The survey was extended by about 60% during May 2018 and September 2018 to include the Bolivar Roads area between the sea jetties. In all ~321 trackline km of data were collected. CHIRP sonar data were collected over the San Luis Pass flood tide delta during three deployments in 2017. In all 24 sub-bottom profiles were collected, totaling 87 km of track data.
All data were sent to the NOAA National Centers for Environmental Information for archiving. Data are currently being used by two University of Houston MS students and one PhD student for thesis research.
Intellectual Merit
The intellectual merit of the project was the opportunity to obtain rare before and after snaptshots of sediment distribution and the effect of the hurricane, potentially illuminating poorly understood coastal sedimentation and erosion processes in the wake of a large tropical cyclone rain event. San Luis Pass data help understand the timing and evolution of tidal delta formation and their relation to storms and coastal sedimentation history.
Broader Impacts
The project provided by the data and information that will be useful for scientific understanding of sedimentation and erosion during tropical cyclones. The data would benefit state and federal managers of Galveston Bay and Bolivar Roads. Several graduate students were trained in geophysical surveying. Approximately 15 undergraduate students were also involved in the data collection, potentially impacting their view of STEM careers. Data collected during the project are currently being used by two MS students and two PhD students for theses and research papers.
Last Modified: 04/12/2019
Modified by: William W Sager
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