Map-Based Flood Hydrology and Hydraulics - PowerPoint PPT Presentation

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Map-Based Flood Hydrology and Hydraulics

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  1. Map-Based Flood Hydrology and Hydraulics David R. Maidment Jan 10, 1998

  2. Map-Based Hydrology and Hydraulics • Connecting ArcView with HMS for the Austin Region • Flood simulation using Nexrad data in Houston • HMS-RAS for Waller Creek in Austin • Creating flood plain maps in Waller Creek

  3. Map-Based Hydrology and Hydraulics ArcView Input Data DEM ArcView Flood plain maps CRWR-PrePro HEC-RAS Water surface profiles HEC-HMS Flood discharge

  4. Austin Digital Elevation Model Waller Creek

  5. Austin Watersheds

  6. CRWR-PrePro Digital Elevation Model Stream Map ArcView-based preprocessor for HEC-Hydrologic Modeling System (HEC-HMS) Control point locations HMS Basin File

  7. Presentation Outline • Using GIS to connect hydrology and meteorology • Representation of spatial objects in GIS • Terrain analysis using Digital Elevation Models • Geodesy and map projections

  8. Study Region in West Austin Hog Pen Ck 4 km 4 km

  9. Watershed Delineation by Hand Digitizing Watershed divide Outlet Drainage direction

  10. 30 Meter MeshStandard for 1:24,000 Scale Maps

  11. DEM Elevations 720 720 Contours 740 720 700 680 740 720 700 680

  12. DEM Elevations Contours 700 680

  13. 32 64 128 16 1 8 4 2 Eight Direction Pour Point Model

  14. 67 56 49 53 44 37 58 55 22 Direction of Steepest Descent 1 1 67 56 49 53 44 37 58 55 22 Slope:

  15. 2 2 4 4 8 1 2 4 8 4 128 1 2 4 8 2 1 4 4 4 1 1 1 2 16 Flow Direction Grid

  16. Austin West 30 Meter DEMElevations in meters ftp://ftp.tnris.state.tx.us/tnris/demA.html

  17. 32 64 128 16 1 8 4 2 Flow Direction Grid

  18. Grid Network

  19. Flow Accumulation Grid 0 0 0 0 0 0 0 0 0 0 0 3 2 2 0 3 2 0 0 2 0 0 1 0 0 11 0 1 0 11 0 0 0 1 15 0 0 1 0 15 1 0 2 5 24 2 5 0 1 24 Link to Grid calculator

  20. 0 0 0 0 0 0 3 2 2 0 0 1 0 0 11 0 0 0 1 15 1 0 2 5 24 Flow Accumulation > 5 Cell Threshold

  21. Stream Network for 5 cell Threshold Drainage Area 0 0 0 0 0 3 2 0 0 2 0 0 1 0 11 0 0 1 0 15 2 5 0 1 24

  22. Streams with 200 cell Threshold(>18 hectares or 13.5 acres drainage area)

  23. Watershed Outlet

  24. Watershed Draining to This Outlet

  25. Watershed andDrainage PathsDelineated from 30m DEM Automated method is more consistent than hand delineation

  26. DEM Data Sources for Texas • Digital terrain models with 2’ or 4’ contours built from aerial photogrammetry • 10m DE-DEMs, from 1:24,000 scale maps with drainage enforcement (experimental) • 30m DEMs from 1:24,000 scale maps • 1” seamless DEM of Texas (March, 1999) • 3" (100m) DEMs from 1:250,000 scale maps (current state-wide coverage)

  27. DEM Watersheds for Austin

  28. Selected Watersheds and Streams Mansfield Dam Colorado River

  29. HMS Schematic Prepared with CRWR-PrePro Mansfield Dam Colorado River

  30. HMS Basin File Basin file is a text description of all hydrologic elements 155 33 87 Subbasin 39 Reach Junction

  31. HMS Model of the Austin Region

  32. Maps Served on the Web

  33. Design Precipitation Input

  34. HMS Control File

  35. HMS Results Watershed 155 Junction 44

  36. Map-Based Hydrology and Hydraulics • Connecting ArcView with HMS for the Austin Region • Flood simulation using Nexrad data in Houston • HMS-RAS for Waller Creek in Austin • Creating flood plain maps in Waller Creek

  37. Regional flood analysis in Houston Study region

  38. Study Region in West HoustonMaps Developed using CRWR-Prepro by Seth Ahrens

  39. Nexrad Rainfall for Storm of Oct 1994

  40. Discharge in Buffalo Bayou at KatyOctober, 1994 storm

  41. Calibrated Flow with HEC-HMS

  42. Map-Based Hydrology and Hydraulics • Connecting ArcView with HMS for the Austin Region • Flood simulation using Nexrad data in Houston • HMS-RAS for Waller Creek in Austin • Creating flood plain maps in Waller Creek

  43. Waller Creek DEM

  44. Waller Creek Watershed Outlets

  45. Waller Creek HMS Model

  46. Flood Plain Mapping

  47. Connecting HMS and RAS

  48. Discharge at a Particular Cross-Section

  49. Map-Based Hydrology and Hydraulics • Connecting ArcView with HMS for the Austin Region • Flood simulation using Nexrad data in Houston • HMS-RAS for Waller Creek in Austin • Creating flood plain maps in Waller Creek