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Summer 2009
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U.S. Army Corps of Engineers Uses GIS for Complete Analysis of Category 5 Hurricane Protection

One Hundred Ways for Fending Off Hurricane Impacts

Highlights

  • ArcGIS enables planners to see the problem and forecast what-if scenarios.
  • GIS helps planners understand the challenges and solutions of the Louisiana coastline.
  • GIS reveals how a degraded habitat loses its ability to absorb storm impact.

The onslaught of storms and surge that beleaguer Louisiana's gulf shore is not a momentary battle. Hurricanes will continue to blow throughout the next millennia, but iron-willed Louisianans have no intention of giving up. Not now—not ever. Since technology is yet unable to halt a hurricane, the best strategy is defense. How does a civilization save lives and buttress its cities against an unrelenting assault of natural disaster?

  click to enlarge
This New Orleans' comprehensive map of alternative options shows floodplain water depths (green areas), suggested buyout structures (purple areas), the existing levees (purple line), and the new levee (red line). It comprises data from a variety of sources and is shared with stakeholders. Congress considers these maps for planning storm surge defense.

Research scientists, engineers, and planners have collaborated to produce more than 100 alternatives for shoring up the state's coast with options that span from 100- to 1,000-year risk reduction. Led by the U.S. Army Corps of Engineers New Orleans District, these professionals are using technology and science to assess the alternatives for coping with the threat of weather, sea, and river to fortify towns and restore natural habitat.

This effort is titled the Louisiana Coastal Protection and Restoration (LACPR) Project, which the U.S. Army Corps of Engineers initiated in response to congressional and executive directives to conduct a complete analysis for Category 5 hurricane protection. The goal is to save lives, property, the environment, and cultural heritage. Corps of Engineers scientists determined potential surge and wave elevations for both frequent and infrequent events based on critical factors, such as wind speed relationships, central pressure, forward speed, and landfalling location.

The technology to support the methodology of this effort needed to be open and easily integrated to ensure a consistent systems approach to modeling storm events, data sharing, alternatives analysis, and lessons learned. For example, project data and modeling are being shared with the Mississippi Coastal Improvements Program and are also tied to the State of Louisiana's master plan for coastal restoration and hurricane protection.

An essential tool planners are using is ArcGIS software that enables them to see the problem and forecast what-if scenarios based on weather severity, changes in population growth, engineering of levees and other infrastructure, effects on environmental habitats, and more. The Army Corps of Engineers has long used Esri software and has a geospatial facility within its Engineer Research and Development Center located in Vicksburg, Mississippi.

At the center, GIS specialists work with research scientists to create databases, develop map layers, assess data relationships, and design predictive modeling methods. Data from contributing agencies' databases and remote data, such as lidar, are input into GIS, which completes calculations and creates data visualizations on an intelligent map. Data can also be run in models. For example, the team used GIS to visualize the Advanced Circulation Model for coastal circulation and storm surge that outputs maps for analyzing hurricane surge and flooding events. Data from various sources, such as the National Hurricane Center, was downloaded to the model. Then the team used GIS to generate situation maps. Output reflected a variety of factors used to predict how often and how severely the region could expect to be inundated during future hurricanes.

The report's hurricane catastrophe defense options have been categorized into three groups. The first is a set of nonstructural alternatives that either relocates people out of harm's way or elevates structures above the floodplain. It involves raising houses; buying out an area; restricting human habitation; and restoring the area to its natural condition, such as reclaiming a neighborhood developed on marshland and returning it to its natural state.

The second is a set of structural alternatives that includes enhancing the existing levees by adding height to them; building new levees, floodwalls, pumps, gates, and weirs; and assessing the value of the floodgate system.

The third is a set of coastal restoration alternatives that targets coastal features as a first line of defense against hurricane surge and waves. GIS reveals how a degraded habitat loses its ability to absorb storm impact. Coastal restoration options that sustain the estuarine environment include development of additional marshland, diversion of rivers, and restoration of shorelines.

Planners are using GIS to model how these options could affect the landscape. Every one of the more than 100 alternatives in the report includes a map representation. GIS models both elevation and water surge levels to predict and demonstrate outcomes.

A draft of the LACPR technical report has been submitted to the National Academy of Sciences for peer review and professional feedback. The Corps of Engineers will soon revise and submit the report to Congress for consideration, planning, and response. The final report will offer Congress an array of alternatives for evaluation and comparison.

More Information

For more information, contact Clint Padgett, chief, Spatial Data Branch, U.S. Army Corps of Engineers, Mobile District (e-mail: clint.padgett@us.army.mil, tel.: 251-694-3721), or visit spatialdata.sam.usace.army.mil. The complete LACPR Plan Formulation Atlas and Draft Technical Report are available online at www.lacpr.usace.army.mil.

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