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WATERWAYS AND BRIDGES IN TEXAS

This presentation explores the hydraulic impact of crash-tested bridge rails on water surface profiles in Texas waterways, particularly in FEMA 100-year floodplains. The goal is to determine the peak discharge for 100-year return period floods and utilize GIS and NFF programs to collect information on flood discharges.

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WATERWAYS AND BRIDGES IN TEXAS

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  1. WATERWAYS AND BRIDGES IN TEXAS CE 394K 11-22-05 Dr. Maidment “Final” Presentation by: Brandon Klenzendorf

  2. Background • TxDOT to use crash-tested bridge rails • May impact FEMA 100-year floodplains • Cause for map revisions – time and money! • Need to determine how bridge rails affect water surface profiles

  3. TxDOT Design Frequencies TxDOT Hydraulic Design Manual

  4. Project Purpose • In order to solve this problem, we need to predict… • Hydraulic impact of crash-tested bridge rails • 100-year peak flood discharges • Determine peak discharge for 100-year return period flood • Use GIS and NFF programs to gain info on flood discharges

  5. GIS Data Collection • State of Texas HUCs from TNRIS • http://www.tnris.state.tx.us/ • Major highway network from TNRIS • Major stream network from TNRIS • DEMs for selected bridges from USGS • http://seamless.usgs.gov/

  6. 1 3 7 10 4 2 8 11 5 9 6

  7. ArcHydro Tools • DEM processing • Problems with gaps in stream layer • Drainage line creation • Batch point watershed delineation • Longest upstream length • Upstream and downstream elevations

  8. Bridge 1 Problems!

  9. USGS NFF Program • National Flood Frequency Program • Estimates the magnitude and frequency of flood peak discharges and hydrographs • 2, 5, 10, 25, 50, 100, and 500-year frequency floods • Uses Visual Basic and regression equations specific for each state • FREE!!! • http://water.usgs.gov/software/nff.html

  10. NFF Program Parameters • Drainage Area (A) – area (mi2) contributing to flow at the bridge • Shape Factor (SH) – ratio of stream length squared (mi2) to drainage area (mi2) • Represents stream length to average width • Stream Slope (SL) – change in elevation (ft) divided by steam length (mi)

  11. Hydrologic Regions • Determined based on physiography and climatic conditions • Each hydrologic region has range of applicable parameters • Hydrologic Region 1 - Q100=371A0.847SH-0.307

  12. Determined NFF Parameters

  13. NFF Interface

  14. Flood Region Map

  15. NFF Results • 100-year hydrograph for five bridges • Bridge 5 has largest peak, but third largest area • Bridge 3 has second lowest peak, but largest area 5 1 4 3 2

  16. Completed Work • Geodatabase of Texas rivers, highways, and HUCs • ArcHydro tools for all bridges • Batch point watershed delineation for all bridges • Partial completion of longest stream length • Partial completion of NFF analysis

  17. Future Work • Longest stream lengths for remaining Hydrologic Regions • NFF analysis for all bridges • Comparison of results • Analyze errors in DEMs, HUCs, and bridge locations • Write final report

  18. Questions ?

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