Water Availability Models

WAM Resolved Technical Issues

What is a water availability model?

A water availability model is a computer-based simulation predicting the amount of water that would be in a river or stream under a specified set of conditions. The model used by TCEQ consists of two parts:

• the modeling program, "WRAP"(Water Rights Analysis Package)
• text files that contain basin-specific information for WRAP to process (input file or WAM)

How are these models used?

TCEQ staff use the models in evaluating water rights applications to help determine if water would be available for a newly requested water right or amendment, or if an amendment might affect other water rights.

• Full Authorization simulation model:
  • all water rights utilize their maximum authorized amounts
  • used to evaluate applications for perpetual water rights and amendments
• Current Conditions simulation model:
  • includes return flows
  • used to evaluate applications for term water rights and amendments

If water is available, these models estimate how often water would be available. For example, would it be available only during very wet times, or would it also be available during very dry times?

In evaluating an application for a new appropriation of water, and some applications for amendments, TCEQ staff must also consider recommended environmental flow needs. Environmental flow needs include instream flows and freshwater inflows to bays and estuaries.

Applicants may also use the models when preparing to apply for a new water right or an amendment.

WRAP: The Modeling Program

The WRAP modeling system includes computer programs for processing basin input files for each river basin in Texas. Texas A&M University maintains these programs, executables, and manuals.

Input files for the model

• New permanent water rights or amendments
  • Full Authorization data set: This model shows the amount of water that would remain available for appropriation if all currently permitted perpetual water rights holders withdrew their full authorized amount of water.
• New term water rights and amendments
  • Current Conditions data set: This model shows the amount of water that would remain available for appropriation if all permitted water rights holders withdrew the amount of water they are now using. Includes return flows.

What do I get with the files?

• Full Authorization (Run 3) or Current Conditions (Run 8) data sets include:
  • *.dat, *.dis, *.eva, *.fad, *.flo, *.txt files and others as applicable.
  • Note: Not all basins include all of these files.
• GIS files include:
  • Water Rights (WR) shapefile: legal representation of all features (reservoirs, diversion points, discharge points, etc.) authorized in the water right
  • Control Points (CP) shapefile: represents the water rights as modeled in the WAM. Not all water rights have CPs if they do not have the authorization to store or divert state water
• WRAP GUI shapefile: intended solely for displaying WRAP output using the WRAP GUI executable, including CP_ID, RES_ID, WR_ID and IF_ID files.
• Flowline shapefile: a representation of the watercourses in the basin.

Input files are compressed in "ZIP" format. You will need the WRAP GUI ( ZipFile) that includes the executable and the user’s manual.

WRAP Input files and GIS files by River Basin

The agency standard used for zipping files is the freeware 7ZIP. If you experience difficulties downloading and extracting data from our site, please try the following:1) download the 7ZIP software from the web and use it to extract the data; and/or 2) contact your IT department and confirm that there are no limitations for downloading the files. The file extensions inside the zip files may be blocked by your firewall. If you still cannot download the data, please contact us at wrap@tceq.texas.gov.

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