The Gulf Coast Aquifer System Groundwater Availability Model (GAM) for the Central and Southern Portions of Gulf Coast Aquifer System in Texas

The Texas Water Development Board has developed a groundwater availability model of the central (Groundwater Management Area 15) and southern (Groundwater Management Area 16) portions of the Gulf Coast Aquifer System in Texas. The model was released in May 2023.

Conceptual Model Report

• Conceptual Model Report: Central and Southern Portions of Gulf Coast Aquifer System in Texas.
• Summary of hydraulic conductivity values from pumping and specific capacity tests
• Summary of storativity and specific yield values from pumping tests

Draft Numerical Recablibration Model Report

The draft update to the groundwater availability model (GAM) for the central and southern portions of the Gulf Coast Aquifer System is currently under public review. The deadline to submit comments to the TWDB is end of day on July 31, 2025.
Please send any comments to gam@twdb.texas.gov.

• Draft Numerical Model Recalibration: Groundwater Availability Model for the Central and Southern Portions of the Gulf Coast Aquifer System (Version 1.1)
• Appendix A: Predictive Analysis and Technical Review of the Groundwater Availability Model for the Central and Southern Portions of the Gulf Coast Aquifer System
• Appendix B: Correlation Wells
• Appendix C: Groundwater Level Hydrographs
• Appendix D: Ensemble Hydrographs
• Appendix E: Simulated Water Budget by Groundwater Conservation District
• Appendix F: Simulated Water Budget by County
• Appendix G: Model Wide Budget

Numerical Model Report

• Numerical Model Report: Central and Southern Portions of the Gulf Coast Aquifer System in Texas
• Appendix A: Simulated Versus Measured Heads
• Appendix B: Groundwater Level Hydrograph
• Appendix C: Simulated Water Budget by County
• Appendix D: Simulated Water Budget by Groundwater Conservation District
• Appendix E: Glossary List
• Appendix F: Stakeholder Comments

Progress Reports

Update on Gulf Coast Aquifer System Groundwater Availability Model for Groundwater Management Areas 15 and 16, July 12, 2018

Update on Gulf Coast Aquifer System Groundwater Availability Model for Groundwater Management Areas 15 and 16, June 25, 2019

Model Files and Associated Data

Please see the GAM files download page for the current model files and associated data.

Email the Groundwater Modeling Department for model files associated with previous versions of the Central portion of the Gulf Coast Aquifer System and Southern portion of the Gulf Coast Aquifer System groundwater availability models.

Stakeholder Advisory Forums (SAF)

A Stakeholder Advisory Forum (SAF) to discuss updates to the groundwater availability model (GAM) for the central and southern portions of the Gulf Coast Aquifer System was held in-person on October 15, 2024.

Send us an email if you would like to receive SAF notifications.

Other Resources

Please see the Gulf Coast Aquifer System, the Central portion of the Gulf Coast Aquifer System Groundwater Availability Model, the Southern portion of the Gulf Coast Aquifer System Groundwater Availability Model, the GMA 16 Groundwater Flow Model, and the Research Projects in Support of Groundwater Models pages for other reports and publications.