1. TAILWATER PREDICTIONS FOR THE LAKE BRAZOS DAM
GIS IN WATER RESOURCES
FALL 2004
BY JACOB YOUNG
HYDRAULIC ENGINEERING, USU

2. PROJECT SCOPE

3. PROJECT SCOPE

4. PROJECT SCOPE

5. OBJECTIVES
PROVIDE INSTREAM FLOWS FOR THE BRAZOS RIVER AT THE TAILWATER OF THE DAM
USE THE SCS CURVE NUMBER APPROACH IN GIS TO DO SO

6. SCS CN METHOD

7. FIRST STEP AQUIRE THE DATA ESTABLISH A PROJECTION NHD DATA DEM’S
LAND COVER
SOILS
PRECIPITATION
ESTABLISH A PROJECTION

8. GIS ANALYSIS
ISOLATE THE TEHUACANA CATCHMENT USING ArcHYDRO

9. GIS ANALYSIS
CREATE CODING SYSTEM

10. GIS ANALYSIS
CREATE CODING SYSTEM

11. GIS ANALYSIS ISOLATE LAND COVER RASTER DATA
ISOLATE SOILS POLYGON SHAPEFILE APPLY CODE SYSTEM
CONVERT SHAPEFILE TO RASTER USING CODE FIELD
SUM CODE FIELDS USING RASTER CALCULATOR

12. GIS ANALYSIS NOW HAVE ENCODED CURVE NUMBER RASTER
JOIN THE LOOK UP TABLE
CONVERT RASTER TO POLYGON

13. GIS ANALYSIS ADD (S) FIELD TO POLYGONS CALC. VALUE WITH EQ.
CONVERT POLYGON TO RASTER USING (S) FIELD AS THE VALUE

14. GIS ANALYSIS APPLY PRECIPITATION DATA
RASTER DATA FOR THE 100 YR. STORM
ISOLATE CATCHMENT PORTION
USE RASTER CALC. WITH (S) VALUE AND PRECIP. RASTERS
AQUIRE WEIGHTED FLOW ACCUMULATION USING ArcHYDRO

15. USING OUTPUTS TO CALC. INSTREAM FLOWS
WEIGHTED ACCUMULATION IS EQUIVALENT TO AQ TERM
D – STORM DURATION
Tc – TIME OF CONCENTRATION

16. QUESTIONS? THANKS TO: FREESE AND NICHOLS ENG. DR. TARBOTON
DR. MAIDMENT
COLLIN ROBINSON