Background
Water Availability by River Basin
Background
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 of a specific river basin consists of two parts:
- the modeling program, called "WRAP", short for Water Rights Analysis Package
- a text file that contains basin-specific information for WRAP to process (these text files are called input files)
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How are these models used?
Water Availability Models are used to determine whether water would be available for a newly requested water right or amendment.
TCEQ staff uses two models in evaluating applications:
- the Full Authorizaton simulation, in which all water rights utilize their maximum authorized amounts, is used to evaluate applications for perpetual water rights and amendments.
- the Current Conditions simulation, which includes return flows, is used to evaluate applications for term water rights and amendments.
If water is available, these models estimate how often the applicant could count on water under various conditions. For example, would water be available only one month out of the year, half the year, or all year? And would that water be available in a repeat of the drought of record?
In evaluating applications for a new appropriation of water and some applications for amendments to existing water rights, TCEQ staff must consider recommended environmental flow needs. Environmental flow needs include instream flows and freshwater inflows to bays and estuaries.
The water availability models provide information that assists TCEQ staff in determining whether to recommend the granting or denial of an application.
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Water Availability by River Basin
What are general water availability maps?
These maps are generated from WAM output for both of the permitting runs (Full Authorization and Current Conditions) for each basin. The maps generally indicate the percentage of months during the period of record that unappropriated water is available at various locations in each basin.
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How are general water availability maps used?
The water availability maps can be used as a general indicator to see if water would be available with sufficient frequency to consider submitting a new application or an amendment to an existing water right. The availability of storage, the total amount requested, the type of use, environmental flow needs and other factors could affect the availability of unappropriated water for a particular project.
In using these maps, please keep these points in mind:
- The maps do not show how much water is present at any given point. If the river is always full but every drop is appropriated, the map will be red, showing that no water is available.
- The maps do not show how much water is available. They show only how often some water is available.
- Each map is valid as of the date shown on the map. New water rights or amendments to existing water rights may have been approved since the maps were created.
- The State Wide Availability Maps provides a very general look at water availability for the entire state. To look at water availability in a specific basin, use the main specific maps.
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General Water Availability Maps by River Basin
Of the twenty three river basins in Texas, maps are available for the following:
Other maps will be posted here as they become available.
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Canadian River Basin Availability Maps
Click on Images to see full-size maps
Full Authorization |
Current Conditions |
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Red River Basin Availability Maps
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Full Authorization |
Current Conditions |
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Sulphur River Basin Availability Maps
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Full Authorization |
Current Conditions |
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Cypress River Basin Availability Maps
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Full Authorization |
Current Conditions |
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Sabine River Basin Availability Maps
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Full Authorization |
Current Conditions |
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Neches River Basin Availability Maps
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Full Authorization |
Current Conditions |
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Neches-Trinity Coastal Basin Availability Maps
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Full Authorization |
Current Conditions |
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Trinity River Basin Availability Maps
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Full Authorization |
Current Conditions |
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Trinity-San Jacinto Coastal Basin Availability Maps
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Full Authorization |
Current Conditions |
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San Jacinto River Basin Availability Maps
Click on Images to see full-size maps
Full Authorization |
Current Conditions |
San Jacinto-Brazos Coastal Basin Availability Maps
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Full Authorization |
Current Conditions |
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Brazos River Basin Availability Maps
Click on Images to see full-size maps
Full Authorization |
Full Authorization |
Current Conditions |
Current Conditions |
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Colorado River Basin Availability Maps
Click on Images to see full-size maps
Full Authorization |
Current Conditions |
Colorado-Lavaca Coastal Basin Availability Maps
Click on Images to see full-size maps
Full Authorization |
Current Conditions |
Lavaca River Basin Availability Maps
Click on Images to see full-size maps
Full Authorization |
Current Conditions |
Lavaca-Guadalupe Coastal Basin Availability Maps
Click on Images to see full-size maps
Full Authorization |
Current Conditions |
Guadalupe River Basin
Click on Images to see full-size maps
Full Authorization |
Current Conditions |
San Antonio River Basin
Click on Images to see full-size maps
Full Authorization |
Current Conditions |
San Antonio-Nueces Coastal Basin Availability Maps
Click on Images to see full-size maps
Full Authorization |
Current Conditions |
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Nueces River Basin Availability Maps
Click on Images to see full-size maps
Full Authorization |
Current Conditions |
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Nueces-Rio Grande Coastal Basin Availability Maps
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Full Authorization |
Current Conditions |
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WRAP: The Modeling Program
All river basin models are compatible with the March 2003 version of WRAP. The TX-WRAP, Tables, and WinWRAP files are compressed in executable (.EXE) format (Help with Downloading Files.)
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Input Files by River Basin
Data files necessary to run the water availability model for the following river basins are available as compressed files in "ZIP" format (Help with Downloading Files.)
Data for the TCEQ permitting runs (Full Authorization and Current Conditions) is available. In addition to the basin specific files needed to run the models, a text file is included in the ZIP file for each permitting run that details recent changes to the input files.
If you need more information, please contact: The Water Rights Permitting & Surface Water Availability Team at 512/239-4691 or send an email to: wras@tceq.texas.gov
It should be noted that the basin input files are dated and the information can change as new and amended water rights are added to the models.
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Canadian River Basin
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Red River Basin
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Sulphur River Basin
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Cypress River Basin
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Sabine River Basin
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Neches River Basin
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Neches-Trinity Coastal Basin
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Trinity River Basin
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Trinity-San Jacinto Coastal Basin
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San Jacinto River Basin
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Brazos River Basin and San Jacinto-Brazos Coastal Basin
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Colorado River Basin and Brazos-Colorado Coastal Basin
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Colorado-Lavaca Coastal Basin
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Lavaca River Basin
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Lavaca-Guadalupe Coastal Basin
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Guadalupe River Basin and San Antonio River Basin
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San Antonio-Nueces Coastal Basin
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Nueces River Basin
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Nueces-Rio Grande Coastal Basin
- Input data for Full Authorization
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- Input data for Current Authorization
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Rio Grande Basin
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