A Coastal Barrier Protecting the Houston/Galveston Region from Hurricane Storm Surge Center for Texas Beaches and Shores Texas A& M University at Galveston The Ike Dike

The Houston/Galveston Region Is home to about 2 Million people and may double by 2050 Galveston Bay provides valuable ecosystem services and supports a vast petrochemical complex Port of Houston alone generates over $117 Billion in economic activity annually Is affected by a major storm about every 15 years Full evacuations are increasing difficult for Hurricanes that quickly increase in intensity and/or change direction

On Sept. 13, Ike passed over Galveston Island Killing over 80 people Causing $32 Billion dollars in damage Damaging sensitive ecosystems and wildlife habitats Devastating our vulnerable (poor, elderly) populations much more than others Had it hit farther west (more towards San Luis Pass) its impacts would have been much more severe Hundreds of lives lost Many more billions in damages

But Even with a “Favorable” Path 81,000 homes 205,000 residents 5,000 businesses 99,000 jobs 42 schools 41 electrical substations 131 wastewater treatment plants 13 hospitals Received a surge of 10 Feet or more

To date, surge reduction strategies have been local: Circling Dikes Coastal Revetments Hardening of Properties Raising Individual Structures But Each Approach has Limitations

A Better Strategy Protect the entire Houston/Galveston Region including Galveston Bay from hurricane surge using a coastal barrier (the Ike Dike) similar to the Dutch Delta Works

Components of the Ike Dike Extension of the existing Galveston Seawall out to the West End (San Luis Pass) Covering a total distance of 18 miles Addition of a seawall on Bolivar Peninsula from Bolivar roads to High Island Covering a total distance of 35 miles Construction of inland “wrap-arounds” or extensions to the Dike at both ends Construction of floodgates at Bolivar Roads, San Luis Pass, and on the Intracoastal Waterway

Galveston Island Bolivar Peninsula Bolivar Roads San Luis Pass Intracoastal Waterway Existing Seawall Proposed Galveston Bay Enclosure

The Dike protects all of Galveston Bay including ship channels

The Galveston Gates Galveston gates will be the costliest component of the Ike Dike and its biggest tourist attraction Must allow water circulation into the bay under normal conditions But close quickly when a hurricane approaches to provide a 17ft higher-than-sea-level barrier across Bolivar Roads Based on flood gates now operating near Rotterdam

Rotterdam Flood Gates protect a channel 1181 ft wide and 75 ft deep

Houston Ship Channel Specifications main channel dredged to project depth of 45 feet and width of 530 feet; 35-foot wide transition slopes on either side of the main channel, measuring 45 feet deep at their innermost point, and 12 feet deep at their outermost point; 200-foot wide barge lanes outside of the transition slopes, measuring 12 feet deep; and, width of the entire channel is 1000 feet

Bolivar Roads

Animation of the flood gates closing

When the gates have closed, they are flooded and drop down and seal the barrier.

Closed Flood Gates

Elsewhere - Can use other flood gate designs – Japanese example

San Luis Pass

Intracoastal Waterway

Rough Costs Seawall Extension:~$1,000,000,000 Bolivar Roads Floodgate:~$ 1,000,000,000 San Luis Pass Floodgate:~$ 50,000,000 Intracoastal Floodgates:~$ 100,000,000 Total Building Cost: ~$ 2,150,000,000 Additional costs will incur if purchase of land is required and there will always be inflation

Sand Re-Nourishment Seawalls can cause beaches to lose sand The Ike Dike Design should include a system to continually re-nourish the beach in front of the seawalls

The Ike Dike Provides Comprehensive Regional Protection from Storm Surge Protects Both Properties and Ecosystems Helps Less Resilient Populations (Poor and Elderly) Costs Much Less than a Single Hurricane Recovery And We Face Recurring (15 yr Interval) Hurricanes Protects Against Hurricanes that Quickly Change Path or Intensity Is Less Costly and More Environmentally Sound than Armoring the Entire Bay System

Center for Texas Beaches and Shores at /