Water Availability Modeling Projects

Texas Groundwater Availability Models

Over the past 10 years, INTERA has led the development of 10 regional-scale groundwater availability models (GAMs) in support of the Texas Water Development Board’s GAM program.  The objective of this program is to provide reliable information on groundwater availability in Texas over a 50-year planning period.  The models are required to be used by the State, Regional Water Planning Groups and Groundwater Conservation Districts (GCDs) to evaluate water management strategies and to assess the potential impacts of Regional Water Plans and GCD Water Management Plans.  Work on each of these GAMs involves data collection and analysis related to aquifer geometry, properties, regional groundwater flow, recharge, surface water/groundwater interaction, and water quality; conceptual model development; model design; pre-development (steady state) and transient calibration; sensitivity analysis; GIS database development and presentation; geology and model visualization; and reporting and web publishing.  The completed GAMs are made publicly available for stakeholders to assess water resource options.  As a result, stakeholder communication and support is integral to the success of the projects.  INTERA holds periodic stakeholder meetings throughout the state to educate and receive feedback from stakeholders.

Water Availability Assessment

INTERA is assisting in evaluating the County’s overall water resources and water availability, as well as determining viable locations for new supply wells.  The work includes: (1) an in-depth study of regional geology and hydrogeology, (2) the development of a regional MODFLOW groundwater model to be used for water resources management, (3) the development of a decision analysis process to evaluate water management alternatives, and (4) the application of the model to address water supply management questions. In developing the geologic model, INTERA worked closely with the USGS on current research on the connection between the Española and Santa Domingo Basins.  A complete GIS repository of hydrogeologic data was organized for use in the design and development of the groundwater availability model. The model covers an area of approximately 1,400 square miles and extends to a depth of over 5,000 feet. GIS was used extensively during model development, as well as to construct the pre-development water table and transient water-level targets that were used to calibrate the model. The underlying geologic model used to develop the numerical flow model is extremely complex due to a variety of folding, faulting, and pinch-outs in the model area. We integrated geologic data and interpreted cross sections to develop a three-dimensional geologic model of the region which was then used to develop the numerical flow model. Because the model area (Española Basin) is an over-appropriated basin, and the entire Santa Fe region is experiencing significant growth, stakeholder communications have been a critical facet of this work.  INTERA assisted the County utility staff in presenting the results of this study at public meetings and at county commissioner meetings. We also provided County staff with formal classroom training on using the model. 

Assessment of Pumping Impacts

INTERA served as the modeling lead for the development of a groundwater model to assess the impacts of additional pumping in the Lower Colorado River Basin as part of the Lower Colorado River Authority (LCRA) and San Antonio Water System (SAWS) Water Project (LSWP). A key aspect of the project, and INTERA's lead responsibility, was the development and application of a groundwater model to simulate the performance and impacts of different well field configurations under different pumping scenarios. Our efforts included developing the groundwater conceptual model, developing a literature database and a GIS database, original data development for aquifer lithology, sequence stratigraphy, and hydraulic properties, developing an initial steady-state model, and developing a variable density cross-sectional model of the Chicot and Evangeline aquifers. As part of this work, we performed a detailed review of aquifer recharge, discharge, water quality, and pumping. An analysis of aquifer stream interaction in the area was performed using hydrograph separation techniques and by developing regressions between precipitation and base flow for several sub basins. INTERA developed the groundwater model and calibrated it to a steady-state period (pre-development) and the historical period. The model  runs from pre-development to current time to capture the complex pumping trend and the resulting re-pressurization that has been observed in the region. The model also required a significant degree of integration with surface water analysts evaluating surface water availability with the Colorado River water availability model and with the team responsible for studying in-stream bays and estuaries.