A Spatial Data Approach for Assessing Groundwater Resources, Risks, and Uncertainty

To address questions related groundwater resources coinciding with areas of unconventional oil and gas development, there is a need to improve how we predict the distribution of potable groundwater and constrain uncertainty with those interpretations. Groundwater resources in several regions are stressed due to the high demand for the resource from competing activities, including those utilizing groundwater to hydraulically fracture unconventional hydrocarbon wells. In addition, these activities also raise questions and concerns about potential impacts to groundwater aquifers coinciding with development of unconventional resources. However, the quality and quantity of data available to characterize and predict the distribution of potable groundwater is inconsistent and in many areas poor. This study demonstrates a hybrid deductive-geostatistical approach for assessing depth to base of potable groundwater. The approach utilizes different sources of groundwater composition data to produce a structure contour interpolation of depth to base of potable groundwater. Our approach also produces a quantitative assessment of the uncertainty with that analysis using the Variable Grid Method (VGM), a geospatial-statistical approach. We demonstrate application of this approach in an analysis of depth to base of potable groundwater for West Virginia and Pennsylvania. The VGM uncertainty layer is integrated with the interpolation of the depth to base of potable groundwater, simultaneously providing the prediction of the distribution of potable groundwater and information about the quality of that prediction. This combination of spatial and statistical analysis provides more information to drive decisions about resource distribution, potential risks of impacts and knowledge gaps that may require additional data acquisition before robust conclusions can be made. Ultimately, this geospatial-geostatistical approach seeks to improve science-based decision making as it relates to both groundwater and hydrocarbon resource development.