1. HEC-PrePro Workshop GIS Research Group Center for Research in Water Resources University of Texas at Austin Francisco Olivera HEC-PrePro v. 2.0 Workshop May 12, 1998

2. Previous Work Watershed Delineator ArcView Extension [ESRI-TNRCC] Flood Flow Calculator ArcView Extension [CRWR-TxDOT] HECPREPRO (v. 1.0) ArcView Project [CRWR-HEC] HEC-PrePro v. 2.0 ArcView Extension [CRWR]

3. HEC-PrePro v.2.0 Components Terrain Analysis Stream-Watershed Delineation (raster and vector) Calculation of Hydrologic Parameters Isolation of a Hydrologic Sub-System HMS Schematic Parameter Transfer HMS Basin File

4. Terrain Analysis Burning-in Streams? Filling SinksFlow DirectionFlow Accumulation

5. Digital Elevation Model (DEM)

6. Hydrologic (Raster-)GIS Functions

7. Burning-In Process

8. Flow Direction zWater flows to one of its neighbor cells according to the direction of the steepest descent. zFlow direction takes one out eight possible values.

9. Flow Accumulation zFlow accumulation is an indirect way of measuring drainage areas (in units of grid cells).

10. Stream-Watershed Delineation (raster) Stream Network (threshold) Stream Network (interactive) Outlets, Control Points and Reservoirs (interactive) Watershed Delineation Outlets (junctions)

11. Stream-Watershed Delineation Model Stream junction node Stream headwater node System outlet node User-defined node Sub-basin Stream

12. Stream Definition zAll grid cells draining more than a user-defined threshold, and located downstream of a user-defined cell are part of the stream network.

13. Stream Segmentation zStream segments (links) are the sections of a stream channel connecting two successive junctions, a junction and an outlet, or a junction and the drainage divide.

14. Watershed Delineation zThe drainage area of each stream segment is delineated.

15. Raster to Vector Conversion Watershed Vectorization Stream Vectorization Watershed Aggregation Dissolving Spurious Polygons

16. Raster to Vector Conversion zStreams and watersheds are converted from raster to vector format.

17. Dissolving Spurious Polygons zCells connected to the main watershed polygon through a corner are defined as a separate polygon (spurious polygon). zThese polygons should be dissolved into the main polygon.

18. Hydrologic Parameters (watersheds) Flow length upstream and downstream Average Curve Number Slope and length of the longest flow-path Identification of the longest flow-path Lag-time SCS Unit Hydrograph

19. Flow Length Downstream to the Watershed Outlet

20. Flow Length Upstream to the Watershed Divide

21. Longest Flow-Path

22. Watershed Lag-Time (SCS) LW :length of longest flow-path (ft) CN :average Curve Number S :slope of the longest flow-path (%)

23. Hydrologic Parameters (streams) Flow time Pure Lag Routing Number of sub-reaches Muskingum Routing

24. Isolation of a Hydrologic Sub-System Selected Watersheds (and corresponding streams) System Source (inlet) Drainage Area of a User-Defined Point Hydrologic Parameters of the Outlet Polygon Shape Files of Watersheds and Streams

25. Isolation of a Sub-System

26. Connection to HEC-HMS HMS SchematicParameter Transfer HMS Basin File Ferdi’s code

27. Connection to WRAP Stream-Watershed Delineation Defining Outlets at All Control Points Stream Connectivity from HMS Schematic

28. Connection to WRAP Stream Connectivity Running WRAP Importing the WRAP Output File Into ArcView Control Point Data Writing a WRAP Input File (ASCII)

29. Where do we want to go? zInclude other unit hydrograph and stream routing options available in HMS. zGenerate an HMS precipitation file from spatial data and hydrologic records. zConnect “HEC-PrePro” to other widely used water-resources and water-quality programs.