18 C R I S I S M A N A G E M E N T — P R E P A R AT I O N A N D R E S P O N S E W I T H G I S One Hundred Ways for Fending Off Hurricane Impacts Highlights n ArcGIS enables planners to see the problem and forecast what-if scenarios. n GIS helps planners understand the challenges and solutions of the Louisiana coastline. n 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? 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 U.S. Army Corps of Engineers Uses GIS for Complete Analysis of Category 5 Hurricane Protection 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. 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. City of Davenport Uses 3D Visualization to Prepare for Flooding By Dave Cox and Kevin James, City of Davenport, Iowa The city of Davenport, Iowa, has a long history of flooding. In the last 33 years, there have been eight major Mississippi River floods that have affected the city. In the early 1980s, Davenport decided to use passive flood protection instead of building permanent flood walls or levees to protect the downtown area. This passive protection plan consists of temporary earthen levees, sandbag walls, pumps, and a series of gates to close storm sewer pipes. To efficiently and effectively complete these tasks before floodwater reaches downtown, the city has developed a detailed flood plan consisting of written procedures and maps for various flood levels. During the winter of 2007–2008, large amounts of snowfall threatened the city with potential flooding in the spring. This risk prompted the public works director to ask GIS personnel to create a demonstration of Davenport’s current flood plan for the city council. GIS staff reviewed the maps in the plan and decided that they could use ArcGIS to create a 3D model that would be a more effective way to convey the different aspects of the plan. They used the ArcGIS 3D Analyst extension’s ArcScene application to create a 3D model that showed which parts of the city would be inundated at various flood stages. This model made it possible for city staff and council to visualize data about how floodwater could affect specific parts of the city at any flood stage. Prior to GIS, Davenport’s flood models took a long time to complete. Staff would print contour maps, then draw red lines on these maps to show where the predicted floodwater levels would reach. Multiple calculations were made to account for the slope of the Mississippi River. Now, GIS provides analysts with the tools to build a 3D model based on information the city already had, such as two-foot contour data, building footprints, storm utility data, street centerlines, and aerial photography. Adding GIS to the workflow for modeling Mississippi River flooding supports a logical progression and produces insightful results. The first step is to create two surface triangulated irregular networks (TINs) using the 3D tool in ArcGIS Spatial Analyst. One TIN represents Using 3D modeling adds dimensional visualization of a pre- the actual ground level. It is created dicted flood level’s relationship to buildings. using the city’s existing two-foot contour data. Another TIN represents the river rise, calculated using river slope data from previous floods, which was collected by Davenport’s engineering/survey division. In the second step, the river TIN’s elevation is set to flood stage zero as a starting point for modeling. In the third step, using ArcScene, analysts offset the base height of the river TIN to various flood stages, then display areas of the city where flooding would or would not occur. The fourth step is to verify the GIS model’s accuracy by comparing its outcomes with paper maps and written documentation from previous years. In the fifth step, analysts add the locations of levees, pumps, and gates to the model, so areas that would be protected by this infrastructure are shown in the visualization.