Hydrogeologic Conceptual Model for the Lower Rio Grande Valley Gulf Coast Aquifer System

With a team of consulting partners, we developed a numerical groundwater availability model to simulate changes in groundwater quantity and quality resulting from increased pumping necessary to meet current and future groundwater demands.

OVERVIEW

The Gulf Coast Aquifer System in the Lower Rio Grande Valley is an important groundwater resource in south Texas. Groundwater use in the valley is expected to increase in response to increased municipal demands. Much of the groundwater in the area is brackish and does not meet drinking water quality standards. To meet the expected municipal demand in the valley, additional brackish groundwater supply will be needed in the future. Brackish groundwater is currently treated at several desalination plants for municipal use in the valley. Additional desalination projects have been recommended in a regional water plan recently developed for the area.

SERVICES

M&A’s work included developing the hydrogeologic conceptual model, which provides the hydrogeologic framework or aquifer layering and characterization of the groundwater system. This project involved evaluating and updating a previous investigation of regional and local information regarding physiography, climate, hydrogeology, groundwater levels and groundwater movement, surface water features, recharge, hydraulic properties for the aquifer units, discharge including well pumping, and groundwater salinity.

Groundwater Modeling

  • Developed a 3D geologic model using Leapfrog Geo software for input to a groundwater flow model grid
  • Evaluated groundwater level data for trends and evidence for cross-formational groundwater movement between aquifer units
  • Organized water quality data and prepared maps and time-series plots of total dissolved solids concentrations as data inputs for a groundwater transport model and for evaluating historical trends
  • Used statistical analyses to evaluate aquifer hydraulic properties
  • Evaluated the surface water delivery network for agricultural and municipal users with regards to groundwater-surface water interactions
  • Evaluated data from the Texas Water Development Board’s Groundwater Database and Brackish Resources Assessment Characterization System (BRACS) database
  • Developed relational and geospatial databases conforming to specific data schemas developed by the state of Texas
  • Developed input datasets for the numerical groundwater model
  • Participated in stakeholder advisory forums and encouraged stakeholder participation from all levels of the public and private sectors