1 / 22

Flash Flood Prediction

Flash Flood Prediction. James McDonald 4/29/08. Introduction - Relevance. 90% of all national disasters are weather and flood related Central Texas – “Flash Flood Alley” Project Goal – To compare flash flood prediction on multiple scales (NWS, LCRA, City of Austin).

ostinmannual
Télécharger la présentation

Flash Flood Prediction

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Flash Flood Prediction James McDonald 4/29/08

  2. Introduction - Relevance • 90% of all national disasters are weather and flood related • Central Texas – “Flash Flood Alley” • Project Goal – To compare flash flood prediction on multiple scales (NWS, LCRA, City of Austin)

  3. Agencies – The main players • NWS – ultimately responsible for issuing flood warning • LCRA – manages flood releases from the Highland Lakes • City of Austin – flood monitoring and emergency management

  4. NWS – West Gulf River Forecasting Center • 1 of 13 NWS River Forecasting Centers • Also includes in house Meteorological forecasting

  5. NWS River Forecast Procedure

  6. NexRAD Radar • 4 km x 4 km grid cell • Rain gages across state used to calibrate radar • Radar - mean areal precipitation (per hour)

  7. Sub-basins • Delineated by USGS streamgage • Total QPF (Quantitative Precip. Forecast) • 6 hr. UH time step • Stage height by USGS rating curve

  8. NWSRFS - (NWS River Forecast System) • Similar to HEC-HMS (good for design) • NWSRFS – good for real time flood forecasting • Sacramento Soil Moisture Accounting Method (SAC-SMA) • Able to adjust soil moisture to tweak model

  9. Human Adjustment

  10. Distributive Modeling • The Future • Finer rainfall distribution instead of mean areal across entire sub-basin • Rainfall variation - GIS

  11. LCRA - Lower Colorado River Authority

  12. The Forecast Spreadsheet – early 1980’s • Inputs: • Colorado River Forecast @ San Saba • Time-lagged tributary hydrographs • WSEL of Lake Buchanan & Lake Travis • Reservoir releases

  13. The Spreadsheet - Forecasting

  14. Catchment Forecast System (CFS) • Post 1997 flood • Integrates HEC programs: • PRECIP • HEC1 • UNET

  15. Hydromet: Hydrometeorological Data Acquisition System

  16. HEC’s Corps Water Management System (CWMS) • Integrates the following models: • HEC-HMS, Hydrologic Modeling System • 289 sub-basins • 205 routing reaches • 18,340 mi^2 • HEC-ResSim, Reservoir Evaluation System Simulation • 7 reservoirs • HEC-RAS, River Analysis System • 864 cross-sections • 347 river miles

  17. History of Austin flooding November 15, 2001: 8” of rain in 6 hr. (reported up to 15”) October 17, 1998: 31 deaths 7,000 people evacuated from homes Property damages ~ $1 billion 454 Austin homes damaged December 20, 1991: 200 homes in Travis and Bastrop counties were completely under water May 24, 1981: 13 drowned, $36 million in damages, Shoal Creek 90 gpm -> 6 million gpm

  18. City of Austin – Am I flooding now? • Flood Early Warning System • Emergency Operations Center

  19. Austin Watersheds – Time is not our friend • 7,000 homes in Austin floodplain • Tc range 30min. – 6 hr. • Lowering arm – low water crossing – marginal success • 20 roads close with 5-yr storm

  20. Flood Early Warning System • Components include: • ~40 creek and lake gauges • ~80 rain gauges • Automated data transfer every 15 minutes to the National Weather Service • High Hazard Dam Action Plan

  21. Conclusions – Final Comparisons

  22. Special thanks to: • Mike Shultz, National Weather Service, Ft. Worth, TX • Matt Ables & Melinda Luna, LCRA • Susan Janek, City of Austin, FEWS Questions?

More Related