1 / 15

Backwater Induced Floodplain Assessment

Backwater Induced Floodplain Assessment. November 30, 2006 GIS in Water Resources Michael Konieczki mkonieczki@mail.utexas.edu. Introduction. Federal Highway Administration Bridges in national highway system need crash tested rails (1968) FEMA regulations:

jacob
Download Presentation

Backwater Induced Floodplain Assessment

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. Backwater Induced Floodplain Assessment November 30, 2006 GIS in Water Resources Michael Konieczki mkonieczki@mail.utexas.edu

  2. Introduction • Federal Highway Administration • Bridges in national highway system need crash tested rails (1968) • FEMA regulations: • 100-yr Floodplain cannot rise by more that 1 foot for bridge construction or modifications • Problems • Older bridges • Effects of railings little understood

  3. TxDOT Regulations • Must pass 50-yr event • Checked for FEMA compliance of 100 yr event • Passage of 100-yr event not always needed Overtopping of a local street bridge in Austin. Source: City of Austin

  4. Project Goals • Develop models for analysis • Pre-processing • Post-processing • Analyze backwater induced floodplains • How significant are bridge structures? • Railings? • World Peace (At least with FEMA)

  5. Study Area • Colorado River • Lake Austin to SH 130 Lake Austin SH 130

  6. Data needs • Pre-constuction • Flowlines • Waterbodies • Basins • DEM’s (Digital Elevation Model) • Roads • Counties • Post-construction • use HEC-GeoRAS

  7. HEC-GeoRAS • GIS tools for HEC-RAS • River models can be • Basic or comprehensive • Bridges modeled simply • Assumes rails clog with debris • Height is to top of rail • Possibly a conservative estimate HEC-GeoRAS calculated floodplain. Source: HEC-GeoRAS use’s’ manual

  8. Methods I (The Good) • NHD data • Used network tools to select information for Colorado River • Built a geodatabase with that information • Texas data • Obtained through online resources • Roads • Counties • 100yr floodplain

  9. Methods II (The Bad) • Processing a DEM into a TIN • 1st: tried to process entire basin – failure • 2nd: processed Travis County – success

  10. Methods III (The Ugly) • GeoRAS • Load NHD data • Good luck! • Draw cross-sections • Data entry of whatever you couldn’t load

  11. Goals Redux • Develop models for analysis • Pre-processing • Post-processing • Analyze backwater induced floodplains • How significant are bridge structures? • Railings? • World Peace (At least with FEMA)

  12. Methods IV – A New Hope • Calibrate GeoRAS model to 100yr floodplain • For the SH 130 bridge only super extreme events will matter anyway • Simulate extreme event (200-yr?) • Change bridge geometry - account for railings • Compare • This may show us the limitations of RAS

  13. Future Work • Possibly change HEC-RAS model • Better simulate bridge deck and railing systems • Develop a tool via model builder • Allow for easy comparison of GeoRas results

  14. Acknowledgements • Tyler Janzen for his NHD help • Nishesh Mehta for his help with CO basin DEM

  15. Questions???

More Related