HURRICANE IKE FIELD INVESTIGATION

Report by Billy Edge, Ph.D, P.E., F.ASCE, and Lesley Ewing, P.E., M.ASCE

On September 13, 2008, Hurricane Ike, a Category 2 hurricane, made landfall near Galveston, Texas. The eye of the hurricane crossed over Galveston Bay and a large region of the Texas and Louisiana coast experienced extreme winds, waves and water levels, resulting in large impacts from overtopping, overwash, wind and wave forces and flooding.  The sustainability and resilience of engineering designs is continuously improved by reviewing the performance of existing designs and processes.  The Governing Board of the Coasts, Oceans, Ports and Rivers Institute of the American Society of Civil Engineers (COPRI of ASCE) recognized the opportunity to gain information from observation of the performance of structures that were affected by Hurricane Ike.  Within two weeks of the storm, COPRI organized a field survey to collect perishable data, with financial support from the ASCE and in cooperation with the GEO Institute.

The purpose of the Hurricane Ike Field Investigation was to survey, examine, document and report the effects of Hurricane Ike on coastal landforms, buildings, coastal structures, infrastructure, marinas and ports.  COPRI provided three field teams, one focusing on port facilities and the other two on coastal buildings, infrastructure and processes.

On October 3, 2008 the two COPRI coastal field teams assembled in Galveston for four days of coastal investigations (Phase I).  The ports field team will deploy as Phase II once sufficient access to the port facilities is possible.  The Phase I teams collected perishable data, made observations and documented conditions.  This will be provided later in a written report of observations and Lessons Learned for use by coastal, port and civil engineers in future coastal development.

The coastal teams focused on beaches, small buildings, coastal structures, bridges, and other civil infrastructure covered the coastal areas from Sabine, including Bridge City from east to the west as far as Surfside Beach. The survey region included coastal areas on both sides of the hurricane path.  Communities both east and west of the eye had significant damage. It also included western side of Galveston Bay.

Scour was apparent throughout most of the damage areas and floating and wind-blown debris was broadly spread.  Large overwash fans were observed often inland of the first row of houses and the most seaward road.  Shorelines that had previously been identified as being beach and dune systems were highly eroded, with flattened or very deflated dunes. Utilities and infrastructure exhibited great damage; water and sewer lines have broken, roads had been undermined or buried in sand and debris, telephone and electric lines collapsed.  Community water towers appeared to be undamaged.  The well-built floating docks that were observed were undamaged, except for one dock area in a covered boat shed.  Older fixed pier systems typically suffered more damage.  The latter was responsible for much of the damages of small commercial and pleasure craft.

There was a broad variety of building types in the storm area, ranging from older slab-on-grade development, elevated buildings built to early flood standards, to current flood standards and even some “fortified homes.  In general, structures built to current or fortified standards performed fairly well.  For Hurricane Ike, elevation seems to be the main factor for building defense.  Many of the surviving buildings had deep piles and the main living area was above the wave height.   Break away walls and lower level stairs detached from the main building and functioned as expected. Slab foundations had extensive damage.  Pile foundation failure was observed both from inadequate pile penetration and wave forces.  On both Bolivar Peninsula and Galveston Island the survey teams were able to identify high water marks, some on buildings, piles, or as debris lines.  Water lines on fixed structures were noted, elevations were estimated and coordinates were recorded.  Perishable data were collected and FEMA teams or LIDAR efforts can survey these locations and establish geodetically-referenced water levels that can be used to calibrate surge models and to update flood elevations.

Galveston Island and Bolivar Peninsula have installed a range of shore protection projects.  Many of these protective efforts survived the hurricane and protected inland development.  The Gulf shore protection was not effective for the surge and flooding that came from the bay side and much of the flooding damage came from the bay.  As with built structures, much of the effectiveness of the shore protection depended upon elevation.  Low revetments and groins were overtopped and some three to five ton stone was displaced.  Geotube barriers were overtopped and some tubes rolled either seaward or landward of their apron or underlayer, and once displaced from their foundation, they tended to flatten and be buried fully or partly in sand.  Beach survey data were acquired in 2003 for this coastal region and again in 2008 via LIDAR.  Post-storm surveys are currently planned by JALBTCX the joint airborne lidar and mapping unit and also the Texas General Land Office.  These data will be acquired soon and comparison of these with previous survey data will allow some analysis of the erosion protection provided by the array of shore protection measures.

In the days and weeks ahead, more storm data will be acquired.  The FEMA surveys and LIDAR will provide additional data on the area.  Water level and wave gages will be collected and the data downloaded.  The data and information acquired by the COPRI field investigation will be analyzed and put into context with other surveys and studies, the significance of various observations will be examined and material from the investigation teams will be condensed into a field assessment and "Lessons Learned” report. 

The field survey efforts could not have been possible without the support and assistance of the many people who helped get the survey teams access to restricted areas, arrange food, lodging, transportation and overall logistics.     

COPRI has previously sponsored teams for similar assessments after Hurricane Katrina (ASCE, 2005) and the 2004 Indian Ocean Tsunami (ASCE, 2005).  Like the previous investigations, a report was produced following the field investigation.

Participants of the two coastal teams are:

Billy Edge, Texas A&M – Team Leader
Spencer Rogers, North Carolina Sea Grant - Team Leader
Robert G. Dean, University of Florida
James Kaihatu, Texas A&M
Lesley Ewing, California Coastal Commission
Mandy Loeffler, Moffatt & Nichol, Houston
Margery Overton, North Carolina State University
Kojiro Suzuki, Port and Airport Research Institute, Japan

Paul Work, Georgia Tech

Garry Gregory, Gregory Geotechnical - ASCE Geo Institute Liaison

Donald Stauble, USACE/ERDC/CHL
Jeffrey Waters, USACE/ERDC/CHL

Eddie Wiggins, USACE/JALBTCX

Marie Horgan Garrett, Coastal Solutions, Inc.

Team members had expertise in sediment dynamics, wave run-up, surge, scour, small structure damage assessment, hydrodynamics, coastal engineering, coastal design, geomorphology, and geotechnical engineering.  Several team members had experience on survey teams for previous disasters and for several team members this was their first investigation.