Contact

Bret M. Webb, Ph.D., P.E., D.CE
Professor
University of South Alabama
150 Jaguar Drive, SH3142
Mobile, AL 36688 USA
Phone: (251) 460-6174
Fax: (251) 461-1400
Email: bwebb@southalabama.edu

Research Positions

Currently seeking multiple graduate students to fill positions at the MS and/or doctoral level. Research topics include: living shorelines, beach and tidal inlet dynamics, barrier island response to extreme events, groundwater impacts to coastal lagoons, and infrastructure resilience. Research assistantships are available. Contact me for more details.

Current Research Assistants

SE Students
Garland Pennison

 

MSCE Students
Kelsey Carpenter
Elizabeth Winter
Jackie Wittmann

 

Undergraduate Students
Evan Mazur
Ian Cox
Morgan Lassitter

Former Students

MSCE Students
Patrick Hautau (2018)
Marshall Hayden (2018)
Kate Haynes (2018)
Justin Lowlavar (2017)
Bryan Groza (2016)
Kari Servold (2015)
Chris Marr (2013)
Richard Allen (2013)
Miyuki Matthews (2012)

 

Post Docs
Jon Risinger
Jungwoo Lee

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We recently completed a two-year collaboration with the USDOT Federal Highway Administration during which we developed a new resource that explains how transportation professionals can implement nature-based solutions to enhance the resilience of coastal highways. The complete implementation guide is available on the FHWA project website (or click on cover image at right). A brief summary is provided below. Additional project resources and reports are also described and linked from the project website, as are the reports from a number of pilot projects conducted around the US.

A webinar is scheduled for October 23, 2019 to assist in the rollout of this new resource. The webinar agenda includes presentations on the new Implementation Guide by Tina Hodges of USDOT FHWA and Bret Webb of the University of South Alabama; an overview of the US Army Corps of Engineers’ Engineering With Nature(R) initiative by Jeff King; and a summary of NOAA resources for nature-based solutions by Kim Penn. Click on this link for more information and to register for the webinar (required).

This Implementation Guide is designed to help transportation practitioners understand how and where nature-based and hybrid solutions can be used to improve the resilience of coastal roads and bridges. Upfront, it summarizes the potential flood-reduction benefits and co-benefits of these strategies. From there, the guide follows the steps in the project delivery process, providing guidance on how to consider nature-based solutions in the planning process, how to conduct a site assessment to determine whether nature-based solutions are appropriate, key engineering and ecological design considerations, permitting approaches, construction considerations, and monitoring and maintenance strategies. The guide also includes appendices with site characterization tools, decision support for selecting nature-based solutions, suggested performance metrics, and links to additional tools and resources.

 

 

FHWA GI Pilot title slide... click for animation

We are wrapping up a one-year collaborative project between USA, the Mississippi Department of Transportation (MDOT), and the US Department of Transportation Federal Highway Administration (USDOT FHWA).  This was one of five pilot projects funded by USDOT FHWA to evaluate the use of green infrastructure for improving the resilience of coastal transportation systems. The pilot projects are an initial step in a more comprehensive effort by USDOT FHWA to develop an implementation guide for nature-based solutions that improve resilience. More information about that project is found at the following link {click here}.

 

Our pilot project with MDOT was focused on improving the resilience of a coastal bridge in Mississippi to hurricane hazards and future sea level rise. More specifically, our green infrastructure approach was designed to address the vulnerability of bridge approaches and low-elevation bridge spans. The causes of damage to the bridge during Katrina were determined through the use of hydrodynamic models. A hindcast simulation of Katrina was performed using the coupled ADCIRC+SWAN models. Those results were extracted and used to force a high-resolution, two-dimensional simulation using the XBeach model. An animation of some of those results is provided below.

 

To that end, a pair of vegetated berms were designed in order to mitigate storm damage now and in the future during extreme events.

 

An overview of the entire pilot project is available in a recorded webinar at the following link {click here for webinar}. Ours is the second presentation in the webinar recording (at about the 25-minute mark). Webinar recordings for all five pilot projects, as well as other presentations in an ongoing USDOT FHWA resilience series, can be found at the following link {click here for all webinars}. A brief animation of our presentation slides is available by clicking on the title slide image in this post.

 

Katrina Hindcast using XBeach, forced with ADCIRC+SWAN output…

XBeach animation

Hindcast of Katrina using XBeach: Terrain elevation contour colors correspond to the lower blue-green-brown-white color scale. Selected bathymetric contours are shown as dashed white lines on the surface. The animated water surface is contoured by significant wave height using the blue-white-red scale. Vectors represent the depth-averaged flow magnitude and direction, but only at every 1/10th grid cell for clarity.

 

Title slide image for ASBPA 2017 presentation

I recently presented the results of a year-long research project on synthesizing the capacity of natural and nature-based features (NNBF) to reduce coastal storm hazards. The presentation was given in the Living Shorelines session at ASPA 2017 in Fort Lauderdale, Florida in October. The project, and presentation, were a collaboration between researchers at USA, the Dauphin Island Sea Lab, Northeastern University, the City College of New York, and the US Army Corps of Engineers Engineer Research and Development Center who funded the project.

 

More than 200 published research papers were identified, evaluated, and synthesized in this work. The synthesis focuses on the ability of marshes, mangroves, maritime forests, seagrasses, reefs, beaches, and dunes to attenuate waves, storm surge, flooding, and erosion. With very few exceptions, the literature does not contain unified methods for analyzing and describing these capabilities, and the range of values describing their performance is broad. Regardless of the uncertainty in published values, there is literature that supports the capacity of each of the NNBF considered to provide some measurable reduction of coastal storm hazards. A logical next step is to perform a detailed meta-analysis on values reported in these publications in order to determine average performance values and characterizations of their uncertainty.

 

A short animation of the presentation can be viewed by clicking on the title slide shown here. Please contact me for a full copy of the presentation.

 

Suggested citation below…

Webb, B. M., Scyphers, S., Cebrian, J., Gittman, R., Sharma, S., Rosati, J. 2017. Evaluating the capacity of natural and nature-based features to reduce coatal storm hazards. American Shore & Beach Preservation Association National Coastal Conference. Fort Lauderdale, FL Oct. 24-27.

boatwakestudysite-westfowlriverWe recently deployed a GoPro Hero 3 camera and two RBR D|wave gages to study boat wakes and boat traffic at a site on West Fowl River (AL) over the Labor Day weekend. The GoPro is set to capture photos every 10 s using the time lapse mode. It is wired to an external battery using the LongShot battery elimination system. The wave gages were configured independently such that one is sampling continuously and the other is processing bursts of waves every five minutes. These two sampling schemes will allow us to study the boat wake signatures in great detail (continuous sampling) and also in summary form (wave bursts). The camera system should allow us to match boat wake signatures with the vessels that generated them. While not perfect, we may also be able to estimate boat size and speed from the time lapse photos.

Here is a time lapse video (~30 seconds) of the installation at our study site…

 

 

Pres-cover-pageThe latest study out of our ACES center (Applied Coastal Engineering & Science) is now available. The study, entitled “Lake Forest Mapping: Analysis of Shoaling and Pool Volumes,” was recently completed for the Lake Forest Property Owner’s Association and the City of Daphne with contracting support provided by the Mobile Bay National Estuary Program. The goals of the study were to determine how much sediment has accumulated in the Lake Forest lake (reservoir) since the time of dam construction in 1973/1974, where the largest accumulations of sediment have occurred, and what the remaining normal pool volume is within the lake.

We collected over 12,000 new elevation measurements within and around the lake to map the sediment elevations and also analyzed eight (8) shallow sediment push cores from the lake bed. The results of the study show that over 300,000 cubic yards of medium to coarse grained sediments have accumulated, or shoaled, within the present-day lake shoreline since 1973/1974. Approximately 80% of the lake has shoaled by some measurable amount since the time of dam construction, with some areas accumulating over ten (10) feet of sediment! As a result, the pool volume of the lake has decreased by about 60% due to the accumulation of sediments. The remaining volume could perhaps accommodate another 90 years of sediment input at the current reported rate of 7800 tons per year (as per Cook & Moss, 2008[1]), but the margin for error is quite large.

I presented these study results at a recent Mobile Bay National Estuary Program’s Project Implementation Committee Meeting. A copy of that presentation [2] can be downloaded {here}.  A copy of the final study report [3] can be downloaded {here}.  Please include proper attribution and/or citation [2,3] when reusing these data, results, graphics, and/or figures.

[1] Cook, M., and Moss, N. 2008. Analysis of Water Quality, Sediment Loading Rates, Biological Resources, and Impacts of Land-Use Change on the D’Olive and Tiawasee Creek Watersheds, Baldwin County, Alabama, 2008. Geological Survey of Alabama, Open File Report 08-11: 92 pp.

[2] Webb, B.M. 2016. Lake Forest Mapping: Analysis of Shoaling and Pool Volumes. Mobile Bay National Estuary Program Project Implementation Committee Meeting. August 18, 2016. Presentation.

[3] Webb, B.M. 2016. Lake Forest Mapping: Analysis of Shoaling and Pool Volumes. University of South Alabama, Center for Applied Coastal Engineering and Science, Technical Report No. 16-002F. 41 pp.