San Antonio River Authority. San Antonio River Authority Floodworks implementation in the San Antonio River Basin. Nefi Garza, PE, CFM

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1 San Antonio River Authority Floodworks implementation in the San Antonio River Basin Nefi Garza, PE, CFM San Antonio River Authority Michael Crenshaw, PE, CFM Anthony J. Henry Wallingford Software, Inc

2 San Antonio River Authority Established May 5, 1937

3 HWY 281 looking south 2002 Olmos Basin Flash Flood Alley

4 Flash Flood Alley IH 10 looking North 2002 Leon Creek

5 Regional Flood Challenges Watershed response times are fast Often less than 1 hour Stream velocities are high Velocities greater than 6 fps are common Event magnitudes are unbelievable

6 South Texas Rainfall Records Thrall (1921): 36 /18 hrs Ingram (1932): 36 /24 hrs D Hanis (1935): 22 /3 hrs Pandale (1954): 32 /24 hrs New Braunfels (1972): 10 /1 hr TS Amelia (1978): 48 /52hrs TS Claudette (1979): 43 /24 hrs Zorn (1998): 32 /18 hrs TS Charley (1998): 18 /4 hrs Kerr County (2002): 42 /5 days Source: NWSFO Austin/San Antonio

7 Operational Rain/Stage Units

8 Fully Operational Coverage

9 Previous Flood Warning Efforts City of San Antonio Flood Warning System 85 ALERT/IFLOWS stations. 19 low water crossing lights. 21 stations currently operating. CRWR Map to Map Brainchild of Dr. David Maidment at the University of Texas Center for Research in Water Resources. Funded by SARA. Integrated modeling and mapping in ArcGIS. Evolved into BRWM Regional Watershed Modeling System. Lower Basin Flood Warning Response System Built in cooperation with the U.S. Army Corp of Engineers. Based on the Susquehanna FWRS. Static inundation areas pieced together using forecast flood elevations. Flood response tables maintained by emergency managers in respective counties.

10 From a NEXRAD Map to a Floodplain Map Center for Research in Water Resources CRWR Component 3: Creating a Flood Inundation Map Component 1: Importing NEXRAD data into Geodatabase and Mapping to Watersheds NEXRAD Data Component 2: Hydrologic & Hydraulic Integration based on common geographic framework Hydrologic Model HEC-HMS Hydraulic Model HEC-RAS FLOODPLAIN MAP Salado Creek, San Antonio Rosillo Creek NEXRAD Rainfall Watersheds Geographic Integration using Arc Hydro Process Operations using Arc 9 Model Builder Component 3 Component 1 Component 4 Component 4 Component 2 Component 4: Geodatabase to HEC-DSS to Geodatabase Component 4 Component 3: Floodmapping from HEC-RAS GIS SDF File DEM Cross Sections with Water Surface Elevations Water Surface Raster Flood Inundation Polygon Time Series in HEC-DSS Time Series in Geodatabase HEC Data Storage System for Time Series Research funded by The San Antonio River Authority

11 Implementation Lower Lower Basin FWRS Static maps to simulate flood inundation Product of ACOE study of Wilson, Karnes, and Goliad Counties ArcGIS application Recently converted to web application Bexar Bexar County FWRS Real-time monitoring, modeling, and mapping Pilot study on Salado Creek is complete Event simulation challenge on Six Mile Creek in progress Coordination with all agencies on EFWS station location/funding in progress DFIRM model conversion in progress

12 Lower San Antonio River HEC-FWRS

13 SARA EFWS/FWRS Map data Model scenarios Collect data Map results

14 Lower Basin FWRS

15 Lower Basin FWRS

16 Lower Basin FWRS

17 Web-FWRS Login

18 Web-FWRS Main View

19 Web-FWRS Forecast View

20 Web-FWRS Magnifier

21 Web-FWRS Damages

22 Web-FWRS Response Table

23 Bexar County Flash flood monitoring & Real Time modeling

24 FEMA DFIRM Project In early 2005 the Federal Emergency Management Agency (FEMA) approached us to update all the flood zone in our 4 counties starting with Bexar County, the most populated. We agreed that this was need in our basin FEMA provided Approximate just over 1.2 million SARA provided over 12 million in matching funds For a total of 13.2 million to update the model in Bexar County and another 3 million for the remaining 3 counties We have a pretty complete modeled Basin

25 Streams and rivers to be modeled and re mapped Over 1700 stream miles in Bexar County

26 The FEMA Models The FEMA models are all HEC-HMS HMS (hydrology) and HEC-RAS (hydraulics) The Hydrology component uses an areal reduction factors to attempt to simulate a storm cell The Hydraulic models are all steady state

27 InfoWorks Demo

28 Conceptual Architecture EAA Models CoSA WSFO SARA Rain db RFC Models EOC USGS

29 Design Data Flow

30 Salado Creek Test

31 Salado Creek Test

32 Salado Creek Test Data from pilot study on Salado Creek

33 Salado Creek Test

34 Comments/Questions Nefi Garza, PE, CFM San Antonio River Authority