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Bull Creek Watershed. Elaine B. Darby GIS – Fall 2005. Direction Provided by Dan Yates, Lower Colorado River Authority (LCRA). Lake Travis. Bull Creek Watershed. ERSI Imagery with NHD Streams. ArcGIS generated Hillshade Layer. Data Gathering & Processing. 10 m & 30 m DEM’s

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bull creek watershed

Bull Creek Watershed

Elaine B. Darby

GIS – Fall 2005

Direction Provided by Dan Yates, Lower Colorado River Authority (LCRA)

slide2

Lake Travis

Bull Creek Watershed

ERSI Imagery with NHD Streams

data gathering processing
Data Gathering & Processing
  • 10 m & 30 m DEM’s
    • Downloaded from USGS Seamless server
    • 10 m DEM clipped for Bull Creek Watershed
    • 30 m DEM extent masked to 10 m DEM
  • NHD Streams & Waterbodies (1:24,000)
  • LCRA Hydromet Gauging Stations
  • NEXRAD Data – Nov, 2004
watershed delineation
Watershed Delineation

Area = 4.553 km^2

Area = 4.475 km^2

30 m DEM

51 Catchments

10 m DEM

52 Catchments

area analysis by dem
Area Analysis by DEM

1.7% Difference

drainlines vs nhd streamlines nhd streamlines blue
Drainlines vs NHD StreamlinesNHD Streamlines - Blue

Default Threshold = 0.81 km2

Threshold = 0.3 km2

Threshold = 0.2 km2

nexrad data provided by dan yates lcra
NEXRAD DataProvided by Dan Yates, LCRA
  • Data Source – National Weather Service – West Gulf River Forecast Center
  • NWS archive – http://dipper.nws.noaa.gov/hdsb/data/nexrad/wgrfc_stageiii.php
  • NCDC Java NEXRAD Tools – http://www.ncdc.noaa.gov/oa/radar/jnx
slide12

NEXRAD Data in GIS

Old Spicewood Springs Road

Photos from Bull Creek Foundation - www.bullcreek.net

nexrad grid nov 14 17 2004 bull creek watershed
Nexrad Grid – Nov. 14 – 17, 2004 Bull Creek Watershed

0 – 0.37

0.37 – 1.02

1.02-1.70

1.70 – 2.35

5.7 inches

2.35 – 2.94

2.94 – 3.53

3.53 – 4.12

4.12 – 4.70

4.70 – 5.29

5.29 – 5.99

5.99 – 6.84

6.84 – 7.91

7.91 – 9.14

9.14 – 10.6

10.6 – 13.6

6.0 inches

lcra hydromet gauges
LCRA Hydromet Gauges

Jollyville SW2

Bull Creek at 360

November 14 – 17 ,2005

Jollyville SW 2

5.80 inches

Bull Creek at 360

6.12 inches

nexrad stage iii data
NEXRAD Stage III Data
  • Stage III – based on reflectivity measurements merged with surface rain gauge observations
  • Hourly precipitation – mm/hr – 4 km2
  • Grid based data
  • Hydrologic Rainfall Analysis Project (HRAP) projection
nexrad projections
NEXRAD Projections
  • Polar Stereographic map projection
  • Spherical Earth vs. Ellipsoidal
    • East-West distances distorted relative to North-South distances

Ref.CRWR Online Report 95-3

A GIS Procedure for Merging NEXRAD Precipitation Data and Digital Elevation Models to Determine Rainfall-Runoff Modeling Parameters (1995)

By Seann M Reed and David R. Maidment

nexrad gis
Reed, Maidment (1999) &

Xie, Zhou, et. al. (2005)

Algorithms to perform coordinate transformations to mesh NEXRAD and DEM

NCDC Java NEXRAD Tools

Vector and Raster Grid Export Options

NEXRAD  GIS

Large data sets – use algorithms

conclusions
CONCLUSIONS
  • 10 m vs 30 m DEM – Catchment Areas
    • Very small difference for Bull Creek Watershed
    • No substantial difference in drainage area using 1% default threshold and ¼ % threshold
  • NEXRAD data
    • Integration into GIS can be done using transformation programs