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Processing Geospatial Data with HEC-GeoRAS 3.1

Processing Geospatial Data with HEC-GeoRAS 3.1. Brad Endres CVEN 689 28 April 2003. Overview. Hydrologic Review Hydraulics Review Applicable Software Data Requirements Major Functions of GeoRAS Demonstration of Capabilities Application to Area of Interest Benefits and Drawbacks

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Processing Geospatial Data with HEC-GeoRAS 3.1

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  1. Processing Geospatial Data with HEC-GeoRAS 3.1 Brad Endres CVEN 689 28 April 2003

  2. Overview • Hydrologic Review • Hydraulics Review • Applicable Software • Data Requirements • Major Functions of GeoRAS • Demonstration of Capabilities • Application to Area of Interest • Benefits and Drawbacks • Questions

  3. Hydrologic Review • Engineering Hydrology • Occurrence, circulation, & distribution of water • Frequency & magnitude of events (flood/drought) for engineering designs Gage station Hyetograph Hydrograph

  4. Hydraulics Review • Hydraulics • Results in design specifications for bridges, culverts, and hydraulic structures • Water Surface profile calculations based on flow data Energy Equation Example Floodplain

  5. Hydraulics Review • Floodplain Delineation • Conventional Method of quad maps & hand calculations • Digital Method • Digital Terrain Model (DTM) in ArcView 3.2 • GeoRAS automates geometry calculations • HEC-RAS models given flow & delineates floodplain • Export back to ArcView for additional grids

  6. Applicable Software • ArcGIS w/ extensions • 3D & Spatial Analyst • HEC-GeoHMS • HEC-GeoRAS • HEC-HMS • Simulates rainfall-runoff for the watershed • HEC-RAS • Simulates water surface profile of a stream reach

  7. Data Requirements • Triangular Irregular Network (TIN) • DEM (high resolution) • use stds2dem.exe if downloading from USGS • Land Use / Land Cover • Manning’s Coefficient • See USGS website CRWR image

  8. Major Functions of GeoRAS • Interface between ArcView and HEC-RAS • What does it do? • PreRAS Menu - prepares Geometry Data necessary for HEC-RAS modeling • GeoRAS_Util Menu – creates a table of Manning’s n value from land use shapefile • PostRAS Menu – reads RAS import file; delineates flood plain; creates Velocity and Depth TINs

  9. Demonstration of Capabilities 3-D Scene • Load TIN • Create Contour Lines 3-D Scene

  10. Demonstration of Capabilities • Create Stream Centerline • Create Banks Theme • Create Flow Path Centerlines • Create Cross Section Cut Lines • Add/Create Land Use Theme • Generate RAS Import File

  11. Demonstration of Capabilities Land Use Theme Stream Centerline Right Bank Flow Path Centerlines Cross Section Cut Lines

  12. Demonstration of Capabilities • Generate RAS GIS import file • Open HEC-RAS and import RAS GIS file • Complete Geometry, Hydraulic, & Flow Data • Run Analysis • Generate RAS Export file

  13. Demonstration of Capabilities • RAS GIS import file:

  14. Demonstration of Capabilities • RAS GIS export file:

  15. Demonstration of Capabilities • New GIS data • PostRAS features • Water Surface TIN • Floodplain Delineation – polygon & grid • Velocity TIN • Velocity Grid

  16. Demonstration of Capabilities • Floodplain Delineation (3-D Scene)

  17. Demonstration of Capabilities Velocity Grid (Darker = Faster) Depth Grid (Darker = Deeper)

  18. Application to Area of Interest • Background on Bolinas Lagoon, CA USGS Map USACE Map

  19. Application to Area of Interest • Bolinas Lagoon, CA USACE Image USACE Image

  20. Application to Area of Interest • Employing ArcView, GeoRAS, and RAS for Main Channel Depth Analysis (1968) PreRAS PostRAS 13.5 ft

  21. Application to Area of Interest • Employing ArcView, GeoRAS, and RAS for Main Channel Depth Analysis (1988) PreRAS PostRAS 21.0 ft

  22. Application to Area of Interest • Analysis of Results • Sensitivity to stream centerline placement • Accuracy improves with more XS cut lines • XS cut lines hard to draw on meandering stream • Possible deepening of the main channel over time • Analysis of area complicated by tidal flows • Validate findings • FEMA floodplain maps • USACE studies Bolinas watershed

  23. Benefits & Drawbacks • Overall Benefits • Elevation data is more accurate with TIN files • Better representation of channel bottom • Rapid preparation of geometry data (point and click) • Precision of GIS data increases precision of geometry data • Efficient data transport via import/export files • Velocity grid • Depth grid Bolinas Lagoon on 10m DEM

  24. Benefits & Drawbacks • Overall Benefits • Floodplain maps can be made faster • Floodplain maps can include several flow scenarios • HEC-RAS allows steady & unsteady flow analysis • GIS tools aide engineering analysis • Automated calculation of functions (Energy Equation) • Structural validation of hydraulic control features • Voluminous data on World Wide Web • Makes data into visual event – easier for your brain to process! More GIS!

  25. Benefits & Drawbacks • Overall Drawbacks • Time required to learn several software packages • Availability of TIN or high resolution data • Estimation of Manning’s Coefficient • Few LU/LC files have this as attribute data • Creating XS cut lines demands attention to detail • Velocity distribution data may not be calculated • HEC-RAS export file without velocity data means no velocity TIN or grid

  26. Questions • What are your questions? New 3-D Viewer in HEC-RAS 3.1

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