M&A uses a GIS-based approach to identify brackish groundwater resources as a future option for meeting statewide water demands.
Client: Central Arizona Water Conservation District (CAWCD) - Time frame: 2008–2009
- Location: Arizona (statewide)
In inland areas of the southwestern U.S. and other parts of the world, desalinating groundwater is a feasible option for increasing limited water supplies in response to escalating water demands. M&A was retained to inventory potential brackish groundwater sources in Arizona that could be used to augment or replace existing Central Arizona Project (CAP) supplies. “Brackish” water has concentrations of TDS between 1,000–10,000 mg/L — roughly equivalent to an EC of 1,600 to 17,000 uS/cm. Our services entailed compiling and analyzing data, investigating favorable areas, and reporting on the study findings.
Our tasks included preparing a comprehensive database of well construction, water level, and water quality data from publicly available sources and then organizing it to identify areas where brackish groundwater met our minimum criteria for volume and well yield. Using a GIS platform, we prepared statewide maps showing the distribution of EC and TDS values, water level conditions, and the estimated volume of brackish groundwater in storage
M&A began evaluating the data by constructing a matrix of relevant factors for all basins and areas containing brackish groundwater. These factors included:
- Anticipated well yields
- Estimated volume of groundwater in storage
- Depth to groundwater
- Estimated lateral and vertical distribution of TDS concentrations
We then reviewed hydrogeologic data and reports and estimated the potential for developing more than 10,000 AFY from each brackish groundwater basin / area in a practicable, sustainable manner. Based on this information and discussions with CAWCD, M&A identified five areas warranting further investigation. Additional tasks were then completed for each:
- Preparing summary groundwater chemistry tables
- Researching and documenting aquifer hydraulic properties
- Identifying the sources of, and contributors to, brackish groundwater
- Mapping the lateral and vertical distribution of EC values
- Evaluating the likelihood of changes in land use or water chemistry over time
- Projecting potential impacts to existing groundwater users if these brackish sources were developed
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