AtkinsRealis USA 20250515 Version 2.7.5.6 FEMA-DCS-Terrain Austin, Texas, USA Texas Water Development Board http://hazards.fema.gov AtkinsRealis USA 20250515 Terrain data, as defined in FEMAs Guidelines and Standards for Flood Risk Analysis and Mapping, describe the digital topographic data that were used to create the elevation data representing the terrain environment of a watershed and/or floodplain. Terrain data requirements allow for flexibility in the types of information used to produce final terrain deliverables. Submission of the terrain data sources allows FEMA to account for the origins of the flood study elevation data. (Source: FEMA Guidelines and Standards for Flood Risk Analysis and Mapping.) Terrain data are used to represent the topography of a watershed and/or floodplain environment and to extract useful information for hydraulic and hydrologic models. (Source: FEMA Guidelines and Standards for Flood Risk Analysis and Mapping) 20250515 MIP Submission Date In work Unknown -104.3 -103.1 31.4 30.4 ISO 19115 Topic Category elevation FEMA NFIP Topic Category Land Surface Relief Topography Digital Elevation Model Elevation Data Slope LIDAR Breaklines Contours DEM Flow Vectors Bare Earth TIN Triangulated Irregular Network Hydro Enforced DEM None REGION 06 STATE TX COUNTY Jeff Davis COUNTY-FIPS 48243 COMMUNITY Jeff Davis County (Unincorporated Areas) FEMA-CID 481251 FEMA-CID 48243C HYDROLOGIC UNIT 13070005 None REGION 06 STATE TX COUNTY Pecos COUNTY-FIPS 48371 COMMUNITY Pecos County (Unincorporated Areas) FEMA-CID 000000 HYDROLOGIC UNIT 13070005 None REGION 06 STATE TX COUNTY Reeves COUNTY-FIPS 48389 COMMUNITY Reeves County (Unincorporated Areas) FEMA-CID 000000 HYDROLOGIC UNIT 13070005 None Acknowledgement of FEMA would be appreciated in products derived from these data. These digital data are produced for the purposes of updating/creating a FIRM Database. Federal Emergency Management Agency mailing

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Washington District of Columbia 20472 USA 1-877-336-2627 fema-riskmap-ithelp@fema.dhs.gov ArcGIS software was utilized in order to create a digital surface model for the Blackwater Draw HUC 8 Watershed project area. The lidar datasets were added to a mosaic dataset and prioritized by date with the most recent dataset taking the first priority. If two datasets are from the same year or flown at similar dates, the accuracy was reviewed to determine the priority. The mosaic dataset was exported to make a seamless bare earth 1-meter DEM for mapping and modeling according to the model area extents, including a 1,000 foot buffer. A 10-ft DEM was used during the stream centerlines creation. Stream centerlines were auto-generated using WISE Terrain Analyst (WTA) and the 10-ft DEM for the 0.5 square mile drainage area. The streams were manually edited using the 10-ft DEMs as a source for horizontal alignment and vertical elevation. These stream centerlines were created for use in the hydraulic analysis. Several routines were then used to take localized elevations from the source topographic data and apply them to the streams. This gave the stream vertices elevation information along the Z axis. The resulting elevations ensure that the streams are lower in elevation than any overbank sumps. A separate routine was then used to ensure that the elevations of these vertices descend in height down to an outfall. The final streams will be delivered with the Hydraulics deliverable. The exported DEM was reviewed through automated QC to check for anomalies and outlier locations based on slope and cells that exceed z-value differences from surrounding cells. Visual review was also performed to check for ground differences at the extents of the datasets for differences in ground values. Where necessary, minor adjustments were made to represent a more accurate bare earth surface using aerial imagery, however no locations were found that required minor adjustments to the DEM. DEM files are the source dataset. Accuracy reports were acquired and confirmed the accuracy of the DEMs was sufficient for use in this project. Checks were performed to ensure the data files can be opened, are georeferenced properly, and cover the geographic area completely. Additionally, field survey checkpoints are obtained to evaluate the accuracy of LiDAR products. As specified in the American Society for Photogrammetry and Remote Sensing (ASPRS) Positional Accuracy Standards for Digital Geospatial Data, checkpoints in vegetated and non-vegetated areas are tested in a project area. A statistical analysis between the difference in elevations of the field survey checkpoints and LiDAR-derived, bare earth elevations at the same locations provides a quality assessment of the LiDAR data. The bare earth surface data is an estimation of the bare earth surface and does not include vegetative and built features. Likewise, it contains estimates of water edges at the time of data collection, and may not reflect current conditions. The bare earth surface will contain voids where insufficient energy was reflected from the surface to generate a valid return from the terrain. Voids in the bare earth surface tend to occur in heavily vegetated areas, water bodies, and beneath buildings, motor vehicles, bridges etc. Fresh or wet asphalt, wet sand and certain types of vegetation can also cause voids or anomalous elevations. The data may have been further processed to remove points found to be within delineated water bodies. Low confidence areas are delineated and provided in a separate dataset. The LiDAR data horizontal accuracy is in compliance with the National Standard for Spatial Data Accuracy (NSSDA) RMSE estimation of elevation data in support of 2-ft contour mapping products as it is referenced in the FEMA Guidelines and Standards for Flood Risk Analysis and Mapping. The 1-meter DEM is comprised of the following data sets with their computed vertical accuracy of 11.3 cm RMSEz at the 95 percent confidence level. 0.0113 Vertical accuracy assessment for the various sources was calculated according to ASPRS and NSSDA specifications. USGS 20190806 digital 20190806 Ground Conditions TOPO1 LiDAR-based terrain dataset used for modeling and mapping. Terrain data used for flood risk analysis go through LiDAR preliminary processing and the unclassified point cloud data are tested as specified in the USGS National Geospatial Program Base LiDAR Specification Version 1.0. Where the Mapping Activity Statement (MAS) requires bare earth post-processing of the floodplain area of interest (AOI), the elevation data are tested and comply with both the Fundamental Vertical Accuracy (FVA) and Consolidated Vertical Accuracy (CVA) requirements. Where no bare earth post-processing is specified, only the FVA requirements apply for LiDAR preliminary processing. The processing of this leveraged data was performed in State Plane Lambert Conformal Conic, Texas North Central Zone (projection), 4202 (projection zone). The FEMA spatial files required are submitted in the Geographic Coordinate System (GCS). 20180420 7.8441500000000005e-008 7.8441500000000005e-008 Decimal degrees North American Datum of 1983 Geodetic Reference System 80 6378137.0 298.257222101 North American Vertical Datum of 1988 0.0001 feet Attribute values Source_Index A spatial data set consisting of polygons depicting the source of terrain DEM. FEMA FIRM Database Technical Reference (available at http://www.fema.gov/guidelines-and-standards-flood-risk-analysis-and-mapping and on the FEMA Risk MAP Knowledge Sharing Site). S_Submittal_Info A spatial data set consisting of polygons depicting the extents of the studied area. FEMA FIRM Database Technical Reference (available at http://www.fema.gov/guidelines-and-standards-flood-risk-analysis-and-mapping and on the FEMA Risk MAP Knowledge Sharing Site). Bare Earth DEM An elevation model where bare-earth elevation values have regularly spaced intervals in latitude and longitude (x and y). FEMA Guidelines and Standards for Flood Risk Analysis and Mapping (available at http://www.fema.gov/guidelines-and-standards-flood-risk-analysis-and-mapping and on the FEMA Risk MAP Knowledge Sharing Site) The Terrain data package is made up of several data themes containing primarily spatial information. These data supplement the elevation datasets by providing additional information to aid flood risk evaluation and flood hazard area delineations. FEMAs Guidelines and Standards for Flood Risk Analysis and Mapping contains a detailed description of the data themes and references to other relevant information. FEMA, Mapping Information Platform mailing

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Washington District of Columbia 20472 USA 1-877-336-2627 fema-riskmap-ithelp@fema.dhs.gov No warranty expressed or implied is made by FEMA regarding the utility of the data on any other system nor shall the act of distribution constitute any such warranty. FEMA-Terrain-Capture http://hazards.fema.gov Contact Distributor 20220805 MIPHelp Federal Emergency Management Agency mailing

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Washington District of Columbia 20472 USA 1-877-336-2627 fema-riskmap-ithelp@fema.dhs.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 http://hazards.fema.gov http://www.epsg.org FEMA NFIP Metadata Content and Format Standard