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 an MSCE student to perform research on groundwater impacts to coastal lagoons. A research assistantship is available. Contact me for more details.

Current Research Assistants

SE Students
Garland Pennison

 

MSCE Students
Patrick Hautau
Marshall Hayden
Kate Haynes
Jackie Wittmann

 

Undergraduate Students
Derek Kelly

Former Students

MSCE Students
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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ADCIRC

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.

 

Fig07 for web site

Our manuscript entitled “Spatial Variability of Hydrodynamic Timescales in a Broad and Shallow Estuary: Mobile Bay, Alabama” has been published by the Journal of Coastal Research. The manuscript is currently available online as a pre-print. The final version with color will be available in the coming months. Please {click on this link} for access to the manuscript.

The results presented in this new manuscript by Webb and Marr (2016) were initially developed as part of Chris Marr’s thesis research back in 2013. This new manuscript presents a much more narrow focus of his work and some new analyses as well. For more information about this work please review the {thesis} by Marr and/or this previous {blog post}.

 

 

NCA 2014 home page link

 

Some of our (me and Dr. Scott Douglass, PhD, PE, DCE) work is featured in the 2014 National Climate Assessment, which was recently released through the US Global Change Research Program web site. Click on the image at right to be directed to the interactive report web site. Our contributions are incorporated into Sectors / Transportation.

 

Since 2010 we have been assisting the US Department of Transportation and ICF International in the Gulf Coast 2 Study focused on the Mobile (AL) area. Our portion of the project was to simulate the effects of climate change on storm surge and waves in Alabama’s coastal counties using advanced hydrodynamic models. These results were used to perform exposure and sensitivity assessments in order to evaluate the vulnerability of transportation systems to storm surge and waves on higher future sea levels. A small portion of this work was incorporated into Sectors / Transportation report of the 2014 NCA. The work has also been specifically referenced in cabinet-level and presidential addresses over the past two years, specifically in response to the damage that Hurricane Sandy caused in New York and New Jersey back in 2012.

 

In light of the significant advances made toward performing exposure and vulnerability assessments during the Gulf Coast 2 Study, FHWA has been supporting the development of a new Hydraulic Engineering Circular (HEC) focused on assessing extreme events. The new manual will serve as a second volume to HEC 25 – Highways in the Coastal Environment. More information can be found on the FHWA climate adaptation web site. I am a co-author of this new manual, along with Dr. Douglass and Mr. Roger Kilgore. The new HEC 25 Volume 2 should be released by FHWA some time in 2014.

 

 

the crew at 5 rivers dock

 

The South Alabama Jag Ski was recently used to map bathymetry and velocity at selected locations in northern Mobile Bay as part of a hydrodynamic model (ADCIRC) study of the area. Bathymetric data were collected in order to update the ADCIRC model mesh and underway velocity profiling was performed for eventual model-data comparison of velocity/discharge and water levels. Areas sampled include:

  • I-10 Cut west of Choccolatta Bay
  • Existing box culverts east of the I-10 / Causeway interchange
  • Pass Picada
  • Apalachee River
  • Sardine Pass
  • Duck Skiff Pass / Justins Bay
  • Blakeley River

 

Pres_Page1

 

One of my graduate students, Chris Marr, recently completed his thesis research on the spatial variability of residence, exposure, and flushing times of Mobile Bay, Alabama. A copy of Chris’ final thesis can be found {here}.

 

I was given the opportunity to present Chris’ research results at today’s 2013 Alabama Water Resources Conference in Orange Beach, Alabama. Click on the image at right for a PDF of the presentation. For those of you that didn’t make it to see the presentation, I narrated a version and have embedded the video below.

 

 

 

*Note: we have modified the results slightly based on recent input from colleagues. The changes generally only affect results in Bon Secour Bay. The narration and presentation show the update results.