Better Defining the Flood Threat Flood Inundation Mapping from the National Weather Service

1. Better Defining the Flood ThreatFlood Inundation Mapping from the National Weather Service 2009 Severe Storms and Hydrology Conference Shreveport, LA Gregory P. Shelton NWS/West Gulf River Forecast Center

2. Advanced Hydrologic Prediction Service • State of the science forecasting • Short and long term probabilistic forecasts • Water supply forecasts • Inundation mapping • Innovation at all timescales • Flash flood modeling • Distributed modeling • Ensemble modeling

3. Goals of AHPS • Provide emergency and water resource managers information … • To make informed risk-based decisions • To optimize the use of resources • Better meet the hydrologic needs of the country … • Plan with confidence and efficiency • Stay out of harms way • Provide valuable water supply information • Enable the NWS to increase forecast skill and warning lead time

4. http://water.weather.gov One internet address… Access to most NWS forecasts and data

5. Rainfall - Past National Image is composed of Best Estimate QPE from the 12 CONUS RFCs Image can be downloaded in Shapefile or NetCDF format Click on map to zoom into states or select WFOs from list Toggles at bottom feature various geographic overlays Various time spans are available from 24 hours to a year Durations beyond 1 day also have Normal, Departure from Normal, and Percent of Normal

6. http://water.weather.gov One internet address… Access to most NWS forecasts and data

7. River Information

8. River Information

9. River Information

10. Better Defining the River Flood Threat Inundation Mapping

11. Customer Input • Familiarity with NWS flood severity categories • Utility of existing flood severity categories • Retain existing flood severity categories • Enhance communication of flood risk by use of inundation graphics (maps)

12. Graphical Flood Impact Information Neuse River at Goldsboro, NC • Partnered with NC Floodplain Mapping Program Office, FEMA, and USGS to develop user-requested graphics to better convey flood threat

13. Initial Steps Tar River Basin, NC Goal – To provide Web based flood inundation maps from the NWS operational forecast environment to emergency managers during flood events. • Used partnered data (LIDAR Topo Engineering Data) from FEMA and NC Floodplain Mapping Program • Built unsteady hydraulic model for 73 miles of Tar River • Mapped flood forecasts in a GIS and presented results in easy to read format over the Web. (Text To Graphics) • Used operationally by SERFC as flood forecast tool during Hurricane Isabel – Sept. 2003

14. Static Libraries “Standard” and “Detailed” image options Predefined river stage levels and associated NAVD88 elevation. Yellow highlight indicates current level displayed.

15. Inundation Mapping Process • Obtain and QC Base Data • LIDAR, Topography, Aerial photography, Rating curves, Engineering data (preferably completed FIS) • Close collaboration with partners and customers • FEMA, River Authorities, USGS, Local EMs • Develop Flood Profiles • Determine boundaries for hydraulic modeling of reach • Determine mapping intervals (1 ft, 2 ft, 4ft, etc.) • Develop flows that match rating curve stage for the mapping intervals • Export profiles to GIS for predetermined levels • Datum consistency!! • Develop/Deploy Public Mapping Libraries • QA/QC by NWS staff • Flood depth grids and Inundation polygons delivered to contractor for development of web deliverables • Final product pushed to AHPS web pages

16. Non-Contiguous Areas Actual Location Move Gage This is Harvard Street This is Heights Boulevard QA/QC Process • Check GeoData • Lat/Lon at gage location • Stream centerline • Roads • Check for non-contiguous inundation areas • Check for correct reference data • Flood categories • Impacts statements • Historical crests

17. Available Products • Map types • Predefined Levels • Flood Categories • Current Forecast • Overlays • Street maps • Aerial photos • Map Tools • Zoom • Mouse over for water depth • Export to multiple formats (including shapefiles) Full map with aerial photo and predefined height displayed Flood categories zoomed to nearby neighborhood Current forecast zoomed to forecast point

18. Initial Inundation Mapping Locations

19. Inundation Mapping for Texas • Most locations currently available • All available by end of 2009 • Partnerships with local governments and river authorities • Additional locations also possible

20. Current Locations http://www.weather.gov/ahps/inundation.php

21. Example – Buffalo Bayou at Shepherd Drive “Standard” and “Detailed” image options Predefined river stage levels and associated NAVD88 elevation. Yellow highlight indicates current level displayed. Depth of water analysis available with Detailed Image

22. Example – Buffalo Bayou at Shepherd Drive Flood Categories available as overlays 100 & 500 Year Floodplains and Floodway Data available as overlays

23. Example – Buffalo Bayou at Piney Point Current Forecast: 60.3 FT at 18 UTC on 4/28/09 Current Forecast: 56.6 FT at 00 UTC on 4/29/09

24. Hurricane Ike N side channel: 54.9 Greens Bayou at U.S Hwy 59 – Crest 58.4 feet 59 S bound feeder: 55.2 Sequoia Estates: 56.3

25. IBWC Partnership • Goal: Implement FIM on the Rio Grande • WMO Voluntary Cooperation Program • Seeking funding to cover implementation • Worked with IBWC to develop grant proposal • Utilize existing base data and modeling from IBWC • Approval delayed and project merged with larger bi-national negotiations • IBWC completed primary modeling work between Amistad and Falcon Reservoirs • Partnering to perform QC of polygons • Seeking new funding sources to cover implementation • State of Texas

26. Potential Mapping Locations El Paso Del Rio Presidio Mapping nearing completion Eagle Pass Future potential mapping locations Columbia Bridge Laredo Rio Grande City San Benito Brownsville

27. Questions/Comments? Contact Info: Gregory P. Shelton, Service Coordination Hydrologist West Gulf River Forecast Center greg.shelton@noaa.gov (817) 831-3289 x219