EVALUATING GEOLOGICAL FORMATIONS AND MANAGING GROUND WATER RESOURCES: CAN WE AFFORD THE EFFORT?

In order to effectively develop and manage a ground water system, the system must be described to the extent that changes can be correctly predicted with time. Full-scale characterization efforts are rarely conducted, however, because costs are assumed to be prohibitive. We challenge this notion. Ground water systems, as with all natural systems, are best described through measurement of multiple variables and through an understanding of variable interaction, including people. In response, we present a set of step-wise geological procedures for use in evaluating ground water systems. These geological procedures emphasize the characterization of rock and fluid properties. The steps in the procedure include 1) problem definition, including identification of stakeholders and products, 2) study design, with emphasis on performing evidence-based hydrogeology studies, 3) database design and construction, 4) data analysis, including univariate, bivariate, and multivariate analyses, 5) development and testing of ground water models that emerge from the analysis, 6) generation of maps and allied products, and 7) provisions for updating the groundwater models as new wells are drilled. Our procedures are focused on assessing rock properties that have a bearing on storativity and flow through porous, fractured, or karstic formations. Because the procedures are focused on prediction of rock properties, the approach can be used to assess and develop both conventional and non-conventional aquifer systems and to assess the suitability of formations for underground material storage (e.g., waste, CO2). These procedures are in no way exhaustive, but based on our experience, these steps are critical to the success of formation evaluation. If one or more of these steps is omitted from the characterization process, the final products will have limited and/or short-term value, particularly in geographic areas with projected long-term population growth. Therefore, addressing typical problems defined within a basin requires a systematic and integrative approach to hydrogeological analysis. The cost of performing a regional formation assessment is a fraction of the cost required for construction of a dam for holding surface water (on a per volume basis).