This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Coastal Services Center's Sea Level Rise and Coastal Flooding Impacts Viewer. The DEM includes the 'best available' lidar data known to exist at the time of DEM creation that meets project specifications for those counties within the boundary of the Houston/Galveston TX Weather Forecast Office (WFO), as defined by the NOAA National Weather Service. The counties within this boundary are: Jackson, Matagorda, Brazoria (portion), Harris (portion), Galveston, and Chambers. For all the counties listed, except for Harris, the DEM is derived from LiDAR data sets collected for the Texas Water Development Board (TWDB) in 2006 with a point density of 1.4 m GSD. LiDAR data for Harris County was collected in October 2001 by the Harris County Flood Control District Tropical Storm Allison Recovery Project (TSARP) with a point density of 2.0 m GSD. Hydrographic breaklines used in the creation of the DEM were delineated using LiDAR intensity imagery generated from the data sets. The DEM is hydro flattened such that water elevations are less than or equal to 0 meters.The DEM is referenced vertically to the North American Vertical Datum of 1988 (NAVD88) with vertical units of meters and horizontally to the North American Datum of 1983 (NAD83). The resolution of the DEM is approximately 10 meters.

Purpose and Intent of Map:This product shows geography at the Census tract level for the scope of nine Texas coastal counties that occupy the USACE Galveston District and are affected by the 100 year flood levels. This map also incorporates Overall Social Vulnerability rankings by Census Tracts. These decimal rankings were converted to percentile format and symbolized in three different categories- (0 to 25 percent, 26 to 50 percent, and 51 to 100 percent). Higher percentile numbers indicate higher vulnerability and risks for that area due to increased percentage of social factors for that geographic area. This data was retrieved from the most up-to-date Social Vulnerability Index (SVI) 2018 released data, and sourced from the CDC and ATSDR.Website: https://www.atsdr.cdc.gov/placeandhealth/svi/data_documentation_download.htmlWhat is CDC Social Vulnerability Index?ATSDR’s Geospatial Research, Analysis & Services Program (GRASP) has created a tool to help emergency response planners and public health officials identify and map the communities that will most likely need support before, during, and after a hazardous event.The Social Vulnerability Index (SVI) uses U.S. Census data to determine the social vulnerability of every county and tract. CDC SVI ranks each county and tract on 15 social factors, including poverty, lack of vehicle access, and crowded housing, and groups them into four related themes:SocioeconomicHousing Composition and DisabilityMinority Status and LanguageHousing and Transportation VariablesFor a detailed description of variable uses, please refer to the full SVI 2018 documentation.Overall rankings were converted to percentile format and symbolized in 3 categories- (0 to 25, 26 to 50, and 51 to 100). Higher percentile indicates higher vulnerability and risks due to increased percentage of social factors associated with risk and vulnerability.

Purpose of App:The app has swiping capabilities to view areas with and without USACE project improvements. The scenario of the 100-year flood event is shown in this map in blue. Moving the swiper left to right shows increased flooding and indicates impacts of without area project improvements.Moving the swiper right to left shows less flooding and benefits of with project area improvements.The app also includes layer of Social Vulnerability (SVI 2018) from the CDC for comparison of socially vulnerable populations and their proximity to flooding affects in the 100 year flood range. Social Vulnerability refers to the extent that persons are likely to have long standing negative effects from natural disasters.These areas are less likely to bounce back after events like flooding. This is due to many factors such as: limited resources and assets, health disparities (such as disabilities), whether or not English is spoken and understood, and is correlated with higher likelihood of living in poverty. All of these factors contribute to a higher risk of losses and harm from natural disasters. The map shows areas of high vulnerability in red; these have the highest chances of loss, and greatest threat of harm from natural disasters. These areas are less likely to bounce back after events like flooding. This is due to many factors such as: limited resources and assets, health disparities (such as disabilities), and higher likelihood of living poverty. All of these factors contribute to a higher risk of losses and harm from natural disasters. There are three categories of vulnerability shown on this map. Areas in red (51% to 100%) refer to areas where people live that are the most at risk. The yellow areas range (26 to 50%), indicate mid-range vulnerability. The green areas of the map (0 to 25%) indicate the lowest vulnerability category.Purpose and Intent of Map:This product shows geography at the Census tract level for the scope of nine Texas coastal counties that occupy the USACE Galveston District and are affected by the 100 year flood levels. This map also incorporates Overall Social Vulnerability rankings by Census Tracts. These decimal rankings were converted to percentile format and symbolized in three different categories- (0 to 25 percent, 26 to 50 percent, and 51 to 100 percent). Higher percentile numbers indicate higher vulnerability and risks for that area due to increased percentage of social factors for that geographic area. This data was retrieved from the most up-to-date Social Vulnerability Index (SVI) 2018 released data, and sourced from the CDC and ATSDR.Website: https://www.atsdr.cdc.gov/placeandhealth/svi/data_documentation_download.htmlWhat is CDC Social Vulnerability Index?ATSDR’s Geospatial Research, Analysis & Services Program (GRASP) has created a tool to help emergency response planners and public health officials identify and map the communities that will most likely need support before, during, and after a hazardous event.The Social Vulnerability Index (SVI) uses U.S. Census data to determine the social vulnerability of every county and tract. CDC SVI ranks each county and tract on 15 social factors, including poverty, lack of vehicle access, and crowded housing, and groups them into four related themes:SocioeconomicHousing Composition and DisabilityMinority Status and LanguageHousing and Transportation VariablesFor a detailed description of variable uses, please refer to the full SVI 2018 documentation.Overall rankings were converted to percentile format and symbolized in 3 categories- (0 to 25, 26 to 50, and 51 to 100). Higher percentile indicates higher vulnerability and risks due to increased percentage of social factors associated with risk and vulnerability.