TAILWATER PREDICTIONS FOR THE LAKE BRAZOS DAM

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TAILWATER PREDICTIONS FOR THE LAKE BRAZOS DAM

• GIS IN WATER RESOURCES
• FALL 2004
• BY JACOB YOUNG
• HYDRAULIC ENGINEERING, USU

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PROJECT SCOPE
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PROJECT SCOPE
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PROJECT SCOPE
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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

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SCS CN METHOD
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FIRST STEP

• AQUIRE THE DATA
• NHD DATA
• DEMS
• LAND COVER
• SOILS
• PRECIPITATION
• ESTABLISH A PROJECTION

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GIS ANALYSIS

• ISOLATE THE TEHUACANA CATCHMENT USING ArcHYDRO

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GIS ANALYSIS

• CREATE CODING SYSTEM

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GIS ANALYSIS

• CREATE CODING SYSTEM

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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

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GIS ANALYSIS

• NOW HAVE ENCODED CURVE NUMBER RASTER
• JOIN THE LOOK UP TABLE
• CONVERT RASTER TO POLYGON

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GIS ANALYSIS

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

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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

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USING OUTPUTS TO CALC. INSTREAM FLOWS

• WEIGHTED ACCUMULATION IS EQUIVALENT TO AQ TERM
• D STORM DURATION
• Tc TIME OF CONCENTRATION

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QUESTIONS?

• THANKS TO
• FREESE AND NICHOLS ENG.
• DR. TARBOTON
• DR. MAIDMENT
• COLLIN ROBINSON