Key Sources & What You Can Download
1. Texas Water Development Board (TWDB) – Flood Planning Data Hub
- The Flood Planning Data Hub provides:
- Floodplain Quilt geodatabase, featuring “Cursory Floodplain (2021)” data and built from multiple inputs like the National Flood Hazard Layer and Base Level Engineering. This is downloadable and layered to prioritize highest-quality data per area.
- Regional Flood Planning Geodatabase Templates that regional planning groups can populate with local data.
- The TWDB also links to external datasets such as FEMA’s NFHL, USGS BLE Viewer, and tools like the Flood Decision Support Toolbox.
2. TWDB GIS Resources Hub
- A centralized ArcGIS hub hosting layers for flood risk, including:
- FEMA Estimated Flood Elevation Viewer (depth grids)
- Flood Mapping Service Center tools like FIRM and BLE datasets
3. FEMA – National Flood Hazard Layer (NFHL) & Flood Map Service Center (MSC)
- NFHL geospatial data: includes flood zones, base flood elevations, and floodway status in shapefile and web service formats.
- MSC allows searches by address, plus downloads of NFHL data, FIRMettes, and product packages.
- FEMA also offers viewers and tools for viewing current, preliminary, and pending flood hazard data.
4. Additional Sources for Broader Context
- University or County GIS webpages (e.g., Williamson County) provide local interactive maps with FEMA flood zones, updates, watershed revisions, and planning layers.
- USGS offers flood maps and forecasting tools like Inundation Mappers, Flood Event Viewer, and the National Water Prediction Service.
- Hazus (FEMA’s GIS modeling tool) can conduct hazard analysis and damage estimation using your GIS data.
Suggested Workflow Overview
| Step | Action |
|---|---|
| 1. Explore the TWDB Flood Planning Data Hub | Download the Floodplain Quilt and regional geodatabase templates for Texas. |
| 2. Use TWDB’s ArcGIS Hub | Visualize layers like FEMA BLE grids and flood elevation data interactively. |
| 3. Access FEMA Data | Via MSC, download NFHL shapefiles, or use FEMA’s viewers for preliminary/pending data. |
| 4. Supplement with Local Authority Tools | Check county or city GIS portals for region-specific flood maps and updates. |
| 5. Analyze with Hazus (Optional) | Use the downloaded GIS data to model potential flood impacts and damages. |
Key Sources & What You Can Download
1. Texas Water Development Board (TWDB) – Flood Planning Data
- Floodplain Quilt Geodatabase (2021 Cursory Floodplain)
- A composite of multiple floodplain sources including BLE, NFHL, and local studies.
- 🔗 Download here
- Regional Flood Planning Geodatabase Templates
- Standard templates used for regional flood data submission.
- 🔗 Access templates
2. TWDB GIS Resources Hub
- Flood Risk & Mapping Layers
- BLE depth grids, flood hazard layers, and related tools.
- 🔗 TWDB ArcGIS Hub – Flood Risk Page
3. FEMA – National Flood Hazard Layer (NFHL)
- NFHL Shapefiles & Map Services
- Flood zones, base flood elevations (BFEs), floodways.
- 🔗 NFHL Data Download (FEMA)
- 🔗 ArcGIS NFHL Viewer
- FEMA Map Service Center (MSC)
- View FIRMettes, preliminary/pending maps, and get FEMA product packages.
- 🔗 FEMA MSC Website
4. NOAA Digital Coast
- Flood Data from Coastal Counties
- Additional flood zone GIS datasets for Texas coastal regions.
- 🔗 NOAA Digital Coast – Flood Data
5. USGS – Flood Data & Mapping Tools
- Flood Inundation Mapper & National Water Dashboard
- Historical and real-time flood mapping layers.
- 🔗 USGS Flood Maps FAQ
6. Local County/City GIS Portals
- Example: Williamson County GIS Flood Maps
- Local FIRM layers, drainage improvements, and updates.
- 🔗 Williamson County Floodplain Management
- Example: Grand Prairie Floodplain Viewer
- View local FEMA zones and apply for floodplain permits.
- 🔗 Grand Prairie Floodplain Info
