Reconnaissance Level Studies on a Storm Surge Barrier for Flood Risk Reduction in the Houston-Galveston Bay

Abstract

The Houston -Galveston area is at significant risk from hurricane induced storm surges. This paper summarizes ongoing studies on flood risk reduction for the region. Firstly, based on a simplified probabilistic hurricane surge model , the return periods of surges within the bay have been estimated. This model framework can be used to assess the effectiveness of several risk reduction interventions. Sketch-and conceptual designs have been made of a storm surge barrier in the Bolivar Roads, that would be part of the Ike Dike coastal protection concept. Such a storm surge barrier would consist of two parts, an environmental section for flow requirements (consisting of caissons with vertical gates) and a navigation section of the barrier (consisting of a barge gate), which would allow unhindered passage of navigation during normal conditions. Future questions and challenges for flood risk reduction in the Bay are identified. Keywords: storm surge barrier, hurricanes, probabilistic analysis, flood risk, coastal protection, flood defences INTRODUCTIONDue to economic development and climate change induced effects such as sea-level rise, the risk of flooding is rising in coastal zone. In areas with larger bays, estuaries or coastal waterways, storm surge barriers can be constructed to temporarily close off these systems during storm surges in order to provide coastal flood protection. For example, in the Netherlands, several barriers have been constructed to protect the Southwest of the country after the catastrophic 1953 floods. As part of the upgraded hurricane protection system of New Orleans that was constructed after hurricane Katrina, several storm surge barriers have been built.The Houston -Galveston Bay is at risk from hurricane induced storm surges as well. After Hurricane Ike in 2008 caused almost US $ 40 billion of damages, the concept of the Coastal Spine or Ike dike (herein further referred to as Ike Dike) has been proposed to reduce flood risk of the Galveston/Houston area ( fig. 1) (Merrell et al., 2011; see also http://www.tamug.edu/ikedike/) The Ike Dike comprises a coastal protection system across the Galveston and Bolivar Islands together with a storm surge barrier in the Bolivar Roads. The Bolivar Roads is the deep-draft entrance channel to the Port of Houston. Such a system would reduce or prevent inflow of the hurricane surge into the bay and thus reduce flood risks. COASTAL ENGINEERING 2014 2This paper gives an overview of some of the ongoing studies that are used to characterize flood risk and analyse and design the Ike Dike and other flood risk reduction solutions for the region. The main elements of the study consist of the development of a simplified probabilistic model to characterize the hydraulic effects of hurricanes on the open coast and within the Bay (section 2) and the conceptual engineering design of a storm surge barrier in the Bolivar Roads inlet (section 3). Future challenges and research questions are identified in section 4 of the paper. PROBABILISTIC ANALYSIS OF HURRICANE SURGE...