Development of Site-Scale Conceptual Model Using Integrated Borehole Methods: Systematic Approach for Hydraulic and Geometric Evaluation

Abstract

Understanding the physical flow mechanisms in aquifer systems is essential in effectively protecting groundwater resources and preserving subsurface environments from a wide range of contaminants. A conceptual model is a simplified representation of a groundwater system and gaining knowledge about the geological features and parameters controlling the flow and transport processes is a crucial first step towards properly constructing a site-scale conceptual model. In this study, we present a multi-step workflow that involves integrated borehole techniques to gain information concerning groundwater flow. Measurements from core-scale to field-scale enable us to better build a subsurface geological structure divided into the unconsolidated layer and the fractured bedrock. In addition, neutron logging and mercury injection capillary pressure techniques allow for the development of vertical porosity distribution in the alluvial layer. For fracture characterization, the fracture geometry is delineated using a series of borehole imaging techniques and single-hole tests to differentiate the individual permeable fractures from other hydraulically inactive fractures. Combining the hydraulic and geometric evaluations, the presence of large-scale connective fracture networks is identified. Our high-resolution three-dimensional (3D) site-scale conceptual model is expected to contribute to improving the reliability and availability of numerical groundwater models.

Application of Vertical Electrical Sounding and Toxicity Tests for the Analysis of Vertical Hydraulic Connectivity through the Vadose Zone

“…Indeed, some phenomena serve as continuous warnings about the deterioration resulting from the improper use of water and other natural resources, although certain issues may necessitate more in-depth investigation for their detection. In the majority of instances, the adverse effects of pollution on both surface and underground hydrological systems are primarily attributed to urbanization processes [4][5][6][7]; this is because the incursion of infrastructure modifies the natural hydrological conditions of a river, for instance, with the construction of dams, spillways, sewage discharges, or dikes, among others [8][9][10].…”