Better Defining the Flood ThreatFlood Inundation Mapping from the

National Weather Service

2009 Severe Storms and Hydrology Conference2009 Severe Storms and Hydrology ConferenceShreveport, LAShreveport, LA

Gregory P. SheltonGregory P. SheltonNWS/West Gulf River Forecast CenterNWS/West Gulf River Forecast Center

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Advanced Hydrologic Prediction Service

State of the science State of the science forecastingforecasting Short and long term Short and long term

probabilistic forecastsprobabilistic forecasts Water supply forecastsWater supply forecasts Inundation mappingInundation mapping

Innovation at all timescalesInnovation at all timescales Flash flood modelingFlash flood modeling Distributed modelingDistributed modeling Ensemble modelingEnsemble modeling

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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

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http://water.weather.govhttp://water.weather.gov

Access to most NWS forecasts and data

One internet address…

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Rainfall - PastRainfall - PastNational Image is composed

of Best Estimate QPE from the 12 CONUS RFCs

Image can be downloaded in Shapefile or NetCDF format

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

Click on map to zoom into states or select WFOs from list

Toggles at bottom feature various geographic overlays

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http://water.weather.govhttp://water.weather.gov

Access to most NWS forecasts and data

One internet address…

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River Information

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River Information

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River Information

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INUNDATION MAPPINGBetter Defining the River Flood ThreatBetter Defining the River Flood Threat

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Customer InputFamiliarity with NWS flood severity Familiarity with NWS flood severity

categoriescategoriesUtility of existing flood severity categoriesUtility of existing flood severity categoriesRetain existing flood severity categoriesRetain existing flood severity categoriesEnhance communication of flood risk by Enhance communication of flood risk by

use of use of inundation graphics (maps)inundation graphics (maps)

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Graphical Flood Impact Information

Partnered with NC Floodplain Mapping Program Office, FEMA, and USGS Partnered with NC Floodplain Mapping Program Office, FEMA, and USGS to develop user-requested graphics to better convey flood threatto develop user-requested graphics to better convey flood threat

Neuse River at Neuse River at Goldsboro, NCGoldsboro, NC

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Initial Steps

Used partnered data (LIDAR Used partnered data (LIDAR Topo Engineering Data) from Topo Engineering Data) from FEMA and NC Floodplain FEMA and NC Floodplain Mapping ProgramMapping Program

Built unsteady hydraulic model Built unsteady hydraulic model for 73 miles of Tar Riverfor 73 miles of Tar River

Mapped flood forecasts in a GIS Mapped flood forecasts in a GIS and presented results in easy to and presented results in easy to read format over the Web. (Text read format over the Web. (Text To Graphics)To Graphics)

Used operationally by SERFC as Used operationally by SERFC as flood forecast tool during flood forecast tool during Hurricane Isabel – Sept. 2003Hurricane Isabel – Sept. 2003

Tar River Basin, NC

Goal – To provide Web based flood inundation maps from the NWS operational forecast environment to emergency managers during flood events.

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Static Libraries

Predefined river stage levels and associated NAVD88 elevation. Yellow highlight indicates current level displayed.

“Standard” and “Detailed” image options

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Inundation Mapping Process Obtain and QC Base DataObtain and QC Base Data

LIDAR, Topography, Aerial photography, Rating LIDAR, Topography, Aerial photography, Rating curves, Engineering data (preferably completed curves, Engineering data (preferably completed FIS)FIS)

Close collaboration with partners and customersClose collaboration with partners and customers FEMA, River Authorities, USGS, Local EMsFEMA, River Authorities, USGS, Local EMs

Develop Flood ProfilesDevelop Flood Profiles Determine boundaries for hydraulic modeling of Determine boundaries for hydraulic modeling of

reachreach Determine mapping intervals (1 ft, 2 ft, 4ft, etc.)Determine mapping intervals (1 ft, 2 ft, 4ft, etc.) Develop flows that match rating curve stage for Develop flows that match rating curve stage for

the mapping intervals the mapping intervals Export profiles to GIS for predetermined levelsExport profiles to GIS for predetermined levels Datum consistency!!Datum consistency!!

Develop/Deploy Public Mapping LibrariesDevelop/Deploy Public Mapping Libraries QA/QC by NWS staff QA/QC by NWS staff Flood depth grids and Inundation polygons Flood depth grids and Inundation polygons

delivered to contractor for development of web delivered to contractor for development of web deliverablesdeliverables

Final product pushed to AHPS web pagesFinal product pushed to AHPS web pages

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QA/QC ProcessActual Location

This is Harvard Street

This is Heights Boulevard

Move Gage

Check GeoDataCheck GeoData Lat/Lon at gage locationLat/Lon at gage location Stream centerlineStream centerline RoadsRoads

Check for non-contiguous Check for non-contiguous inundation areasinundation areas

Check for correct reference Check for correct reference datadata Flood categoriesFlood categories Impacts statementsImpacts statements Historical crestsHistorical crests Non-Contiguous Areas

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Available Products Map typesMap types

Predefined LevelsPredefined Levels Flood CategoriesFlood Categories Current ForecastCurrent Forecast

OverlaysOverlays Street mapsStreet maps Aerial photosAerial photos

Map ToolsMap Tools ZoomZoom Mouse over for water depthMouse over for water depth Export Export to to multiple formats multiple formats

(including shapefiles)(including shapefiles)

Current forecast Current forecast zoomed to forecast zoomed to forecast pointpoint

Flood categories Flood categories zoomed to nearby zoomed to nearby neighborhoodneighborhood

Full map with aerial Full map with aerial photo and predefined photo and predefined height displayedheight displayed

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Initial Inundation Mapping Locations

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Inundation Mapping for Texas

Most locations currently Most locations currently available available

All available by end of 2009All available by end of 2009 Partnerships with local Partnerships with local

governments and river governments and river authoritiesauthorities

Additional locations also Additional locations also possiblepossible

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Current Locations

http://www.weather.gov/ahps/inundation.php

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Example – Buffalo Bayou at Shepherd Drive

Predefined river stage levels and associated NAVD88 elevation. Yellow highlight indicates current level displayed.

“Standard” and “Detailed” image options

Depth of water analysis available with Detailed Image

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Example – Buffalo Bayou at Shepherd Drive

Flood Categories available as overlays

100 & 500 Year Floodplains and Floodway Data available as overlays

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Example – Buffalo Bayou at Piney Point

Current Forecast:60.3 FT at 18 UTC on 4/28/09Current Forecast:56.6 FT at 00 UTC on 4/29/09

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Hurricane Ike

Sequoia Estates: 56.3 59 S bound feeder: 55.2

N side channel: 54.9

Greens Bayou at U.S Hwy 59 – Crest 58.4 feet

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IBWC Partnership Goal: Implement FIM on the Rio GrandeGoal: Implement FIM on the Rio Grande

WMO Voluntary Cooperation ProgramWMO Voluntary Cooperation Program Seeking funding to cover implementationSeeking funding to cover implementation Worked with IBWC to develop grant proposalWorked with IBWC to develop grant proposal Utilize existing base data and modeling from IBWC Utilize existing base data and modeling from IBWC Approval delayed and project merged with larger Approval delayed and project merged with larger

bi-national negotiationsbi-national negotiations IBWC completed primary modeling work between IBWC completed primary modeling work between

Amistad and Falcon ReservoirsAmistad and Falcon Reservoirs Partnering to perform QC of polygonsPartnering to perform QC of polygons Seeking new funding sources to cover implementation Seeking new funding sources to cover implementation

• State of TexasState of Texas

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Potential Mapping LocationsEl Paso

Presidio

Rio Grande City

San Benito Brownsville

Del Rio

Eagle Pass

Laredo

Columbia Bridge

Mapping nearing completion

Future potential mapping locations

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Questions/Comments?

Contact Info:Contact Info:Gregory P. Shelton, Service Coordination HydrologistGregory P. Shelton, Service Coordination Hydrologist

West Gulf River Forecast CenterWest Gulf River Forecast Center

greg.shelton@noaa.gov

(817) 831-3289 x219(817) 831-3289 x219