1. Regional Hydraulic Model for the City of Austin
CE 394 K2 - Surface Water Hydrology
Esteban Azagra

2. Objectives Create a “regional hydraulic model” for the city of Austin.
Specific goal: flow analysis.
Dentritic network
Single Creek

3. Tools
CRWR-PrePro: ArcView preprocessor that extracts information from digital spatial data and creates an input file for non-GIS applications.
HEC-HMS: Hydrologic Modeling System for precipitation-runoff simulation.
HEC-RAS: one-dimensional Hydraulic Model for channel analysis and floodplain determination.

4. Methodology
Watershed delineation and HMS schematic generation with PrePro.
Generate flows with HEC-HMS.
Compare flows and run HEC-RAS.

5. Sample Area Branched Relatively flat Cross-sections available
Bull Creek
Little Bull Creek
Branched
Relatively flat
Cross-sections available

6. Data required for the Study
Bull Creek Boundaries (City of Austin)
River Reach File 3 Coverage (EPA)
10 m DEM (City of Austin)
Land Use/Land Cover files (USGS)
Precipitation data (CRWR)
Cross-Sections in GIS format (CRWR)
RAS files (City of Austin)
STATSGO (USDA-NRCS)

7. Working with CRWR-PrePro
DEM
Fill Streams
Basic Stream
Network
“Burning in”
Flow dir.
Flow acc.
Control Points,
Outlets and Links
Delineate
watersheds

8. Working with CRWR-PrePro
Stream Parameters
X = 0.15, V = 1 m/s
Vectorization CN
LULC
Statsgo
Computation of
the hydrologic
parameters
HMS
“Clipping out”
Schematic and
basin file

9. Running HEC-HMS (Basin Model)

10. Running HEC-HMS (Precipitation Model)
Flooding analysis
based on:
2, 10, 25, 100 yr
hypothetical storms
3 hr storm duration

11. Running HEC-HMS (Control Specifications)

12. Running HEC-HMS (Results)
Hydrograph Plot
Hydrograph Time Table
Hydrograph Summary

13. Flow analysis

14. Conclusions Differences are too big!
Check City of Austin flow values.
Model calibration? (X, Vs)
Very suitable approach for flow determinations.
Analysis of big areas.
HMS flow values can be exported to RAS.

15. Future work GIS representation of flooded areas. Work with DOQ’s.
AVRAS.
Other approaches (TIN not available).

16. Questions