Water%20Availability

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Water Availability

• 1996 Texas drought
• Governor Bush asks how much water do we have?
  How much are we using? How much do we need? --
  Ooops. No good answers!
• 1997 Senate Bill 1 passed by Legislature
• Regionalizes water planning in Texas and
  establishes surface water availability modeling
• 2001 Senate Bill 2 passed by Legislature
• Establishes groundwater availability modeling and
  initiates instream flow assessment

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Improvements from Senate Bill 1Water Modeling
and Planning

• Before Senate Bill 1, water planning was done
  state-wide by TWDB
• SB1 established 14 water planning regional
  groups, who are now responsible for planning
  water supply in their area

Water Availability Modeling (TNRCC)
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Improvements from Senate Bill 1Digital Map of
Texas 100K ? 24K
1 Quadrangles 1100,000 scale Approx. 100 maps
cover Texas
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7.5' Quadrangles 124,000 scale 4400 maps cover
Texas
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Improvements from Senate Bill 1 Water
Availability Modeling
Sulphur
Brazos
Trinity
8000 water right locations
Colorado
23 main river basins
Rio Grande
City of Austin
Nueces
Inform every permit holder of the degree of
reliability of their withdrawal during drought
conditions (TCEQ)
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CRWR Mission for Senate Bill 1

• CRWR (UT Austin) aids in the response to Senate
  Bill 1 by providing to TNRCC watershed parameters
  defined from geospatial data for each water right
  location
• These data are input by TCEQ contractors to a
  Water Rights Assessment Package (developed at
  TAMU) which determines the chance that the
  water will actually be available at that location
• TCEQ sends the owner of the water right a letter
  specifying the availability of water

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Water Rights in the Sulphur Basin
Water right location Stream gage location
Drainage areas delineated from Digital Elevation
Models are used to estimate flow at water right
locations based on flow at stream gage locations
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Digital Elevation Model
75
77
79
85
92
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Topographic Map of West Austin124,000 scale
Hog Pen Ck
4 km
4 km
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Digital Elevation Model (DEM)
720
720
Contours
740
720
700
680
680
700
720
740
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Austin West 30 Meter DEM
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(No Transcript)
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Eight Direction Pour Point Model
Water flows in the direction of steepest descent
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Flow Direction Grid
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Cell to Cell Grid Network Through the Landscape
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Streams and Watersheds Defined from the DEM
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Comparison of Drainage Areas
DEM
Difference is 0.5
USGS
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Watershed Properties Averaged over the Drainage
Area

Property grid (CN or Precipitation)
Drainage Areas
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Connectivity of the Control Points
Neches Basin
This flow order is used in the Water Rights
Analysis Package
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Data Products
GIS coverages for determining watershed
parameters
Watershed parameters as input for WRAP model

Analysis completed for more than 10,000 locations
in all river basins of Texas
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Ralph Wurbs ______________________________________
Professor and Division Head Environmental and
Water Resources Division Department of Civil
Engineering Texas AM University College Station,
Texas 77843 r-wurbs_at_tamu.edu [phone]
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Water Availability Modelingin TexasPursuant to
1997 Senate Bill 1

• Water Rights Analysis Package (WRAP) model
  developed at Texas AM University and adopted for
  Texas WAM System
• Water Availability Modeling (WAM) System
  implemented by TNRCC/TCEQ, its partner agencies,
  and contractors pursuant to Senate Bill 1 (SB1)
  enacted by the Texas Legislature in June 1997  

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Internet Sites

• http//ceprofs.tamu.edu/rwurbs/
• WRAP software and reference and users manuals
• http//www.tnrcc.state.tx.us/permitting/
• waterperm/wrpa/wam.html
• TCEQ Water Availability Models

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Water Availability Modeling Process

• Historical Hydrology
•  
• Develop sequences of naturalized monthly flows
  for the period-of-analysis at selected gaging
  stations.
• Distribute flows from gaged sites to ungaged
  sites.
• Current Water Management and Use
•  
• Simulate a specified scenario of water
  management/use during an assumed repetition of
  historical hydrology.
•  
• Develop measures of water supply reliability and
  water availability.

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Water Rights Analysis Package (WRAP)

•  
• Generalized model for simulating management of
  rivers, reservoirs, and water use in a river
  basin or multiple-basin region under a
  priority-based water allocation system.
• Tool for evaluating hydrologic and institutional
  water availability.
• Set of Fortran computer programs.

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Features of WRAP

• Spatial configuration (control points)
• Hydrologic period-of-analysis
• Natural hydrology
• Water management and use
• Water availability indices

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Natural Hydrology

• Naturalized flows at gaged sites
• Flow distribution to ungaged sites
• Channel losses
• Net reservoir evaporation-precipitation

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Water Management and Use

• Water right priorities
• Water supply diversions
• Return flows
• Reservoirs
• Multi-reservoir system operations
• Off-channel reservoirs
• Interbasin transfers
• Instream flow requirements
• Hydroelectric power

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Water Availability Indices

• Volume reliability
• Period reliability
• Frequency relationships for storage, regulated
  flows, and unappropriated flows

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Current WRAP Development Efforts

• Daily time step features
• Conditional reliability model
• Salinity tracking
• Other Continuing refinements

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Observations Regarding Texas WAM Project

• Model development is an institutional partnership
  effort.
• Many people contribute.
• Regulatory and planning functions are integrally
  related.
• A modeling system is constructed rather than just
  a model.
• Data management is a governing concern.
• Model development is a process of continual
  expanding and improving.
•