1. Urbanization and the Effect on Watershed Hydrology
Chris Maxwell-Gaines
Community and Regional Planning

2. Project Methodology Locate appropriate watershed Download data
Delineate watershed for stream gage
Intersect land use layers
Compare storm events to stream gage response
Compare stream flow to storm events
Calculate results
I wanted to locate watersheds that had a certain dominance of land use change over time (nearly all residential or commercial, etc)
Review available data to find watershed with historical stream flow data and near the suburban edges of the city
Download data and delineate watershed from the USGS gage
Intersect land use layers with new watershed and calculate change in LU areas
Compare storm events to stream gage response
Calculate results

3. Description of Bull Creek
Creek length: 11 miles
Drainage area: 25 sq. miles (16,000 ac)
Drains to Colorado River at Lake Austin
Projected Population Growth:
2000: 43,709
2030: 69,716
Source: City of Austin

4. Watershed delineation from DEM
Delineate watershed using USGS gage as an basin outlet
Delineation included West Bull Creek

5. GIS layer from COA doesn’t match delineation

6. Land use circa 1980 Legend: Residential Commercial / Industrial
Undeveloped / Open Space
Transportation
Mining
Water
Bull Creek
Source: EPA - LULC

7. Land use circa 2003
Land use for 2003 had to be consolidated for comparison with 1980 data
Bull Creek
Source: City of Austin

8. Consolidation of Land uses
We have all of this wonderful LU data, but I had to dumb down the land uses to the 1980’s level.

9. Intersection of 1980 Land Use and Bull Creek gage watershed
USGS Stream Gage:
Bull Creek at Loop 360

10. Intersection of 2003 Land Use and Bull Creek gage watershed
USGS Stream Gage:
Bull Creek at Loop 360

11. Change in Land Use
1980 Land use was created from aerial photography – Not exact!
2003 Land use data is more refined hence the inclusion of Transportation layer
Transportation was a land use in 1980 data but pertained to large highways and other facilities

12. USGS Stream Flow Data

13. Precipitation Record for Bull Creek

14. Historical Precipitation for Bull Creek
Identify storm events during these 3 years of similar precipitation
Choose storm events that are large enough to cause noticeable rise in stream flow
Storms larger than 1 inch

15. Representative Storm Events
Storm events isolated to one day events
Attempted to match precipitation level
Will examine more storms for final report

16. Extreme Storm Events

17. Further Research for Project
Calculate storm run-off volume and normalize it to amount of precipitation
Perform statistical analysis
Review land use consolidations
Exam the precipitation and stream flow data closer
Intensity of rainfall does have a tremendous effect. Isolate single day storms rather than multiple day rainfall events.

18. Questions? Preguntas?