1. Hydrologic Cycle

2. Hydrologic Cycle Processes Surface Water Soil water Atmospheric water Groundwater Processes Precipitation Evaporation Surface Runoff Groundwater Recharge Baseflow

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

4. GIS-Based Flood Modeling Terrain analysis using Digital Elevation Models Flood hydrology model for the Austin region Creating flood plain maps for Waller Creek Real time flood emergency management

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

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

7. 30 Meter Mesh Standard for 1:24,000 Scale Maps

8. DEM Elevations Contours 720 700 680 740 680700720740 720

9. 32 16 8 64 4 128 1 2 Eight Direction Pour Point Model

10. DEM Elevations Contours 700 680

11. Austin West 30 Meter DEM Elevations in meters ftp://ftp.tnris.state.tx.us/tnris/demA.html

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

13. Grid Network

14. 00000 0 0 0 0 0 0 0 0 032 2 11 1 1 15 25 24 1 00 0 00 0 0 0 0 0 0 0 0 0 322 11 1 1 1 2 15 245 Flow Accumulation Grid

15. 00 0 00 0 0 0 0 0 0 0 0 0 322 11 1 1 1 2 15 245 Flow Accumulation > 5 Cell Threshold

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

17. Watershed Draining to This Outlet

18. Watershed and Drainage Paths Delineated from 30m DEM Automated method is more consistent than hand delineation

19. DEM Data Sources 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) 30” (1km) DEMs global coverage

20. 7.5´ 1º 3" (100m) DEM 30m DEM Coverage of DEMs 1” seamless DEM

21. Cell Size30m (1”)100m (3”)

22. GIS-Based Flood Modeling Terrain analysis using Digital Elevation Models Flood hydrology model for the Austin region Creating flood plain maps for Waller Creek Real time flood emergency management

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

24. Austin Digital Elevation Model Waller Creek

25. Austin Watersheds

26. CRWR-PrePro ArcView-based preprocessor for HEC-Hydrologic Modeling System (HEC-HMS) Digital Elevation Model Stream Map HMS Basin File Control point locations Soil and Land Use Maps

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. SCS Runoff Curve Number method determines the direct runoff from storm rainfall in small watersheds. Curve number (CN) is a function of hydrologic soil group and land use.

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

32. HMS Model of the Austin Region

33. Design Precipitation Input

34. Maps Served on the Web

35. Nexrad Rainfall for Storm of Oct 1994

36. HMS Results Watershed 155Junction 44

37. GIS-Based Flood Modeling Terrain analysis using Digital Elevation Models Flood hydrology model for the Austin region Creating flood plain maps for Waller Creek Real time flood emergency management

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

39. Waller Creek DEM

40. Waller Creek HMS Model

41. Flood Plain Mapping

42. Connecting HMS and RAS

43. Discharge at a Particular Cross-Section

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

45. HEC-RAS: Background River Analysis System model of the U.S. Army Corps of Engineers Input = cross-section geometry and flow rates Output = flood water elevations Cross-Section Schematic

46. Points describe channel and floodway geometry Bank station locations Water surface elevations and floodplain boundaries HEC-RAS: Cross-Section Description

47. HEC-RAS: Output Text File Graphical

48. Data translation from HEC-RAS text file to dbase table Bank and floodplain boundaries measured from stream centerline HEC-RAS: Data Translation

49. Digital orthophotograph and road coverage used as a base map User digitizes stream with mouse Boundary points define the RAS stream Digital Stream Mapping

50. Floodplain Mapping: Plan View

51. 3D Terrain Modeling: Ultimate Goal

52. GIS-Based Flood Modeling Terrain analysis using Digital Elevation Models Flood hydrology model for the Austin region Creating flood plain maps for Waller Creek Real time flood emergency management

53. Real-time flood emergency mapping Flood hydrology analysis system Nexrad radar rainfall input Precomputed flood map library Real time Offline