Adaptive Work Strategy for Evaluating a Conceptual Site Model

Abstract:

A comprehensive, diagnostic, procedural and adaptive scheme involving a combination of geophysical and direct push methods was developed and applied in the Wurmlingen study site situated within the region of Baden-Württemberg (southwest Germany). The goal of the study was to test the applicability of electrical resistivity method in imaging resistivity contrasts, and mapping the depth to and lateral extent of field-scale subsurface structures and existence of flow paths that may control concentration gradients of groundwater solution contents. Based on a relatively fast and cost-effective areal mapping with vertical electrical sounding technique, a northwest-southeast trending stream-channel-like depression (low apparent resistivity feature) through a Pleistocene aquifer was detected. For a more detailed characterization, we implemented electrical resistivity tomography method followed by direct push (DP) technologies. Beside the use of DP for verification of structures identified by geophysical tools, we used it for multi-level groundwater sampling. Results from groundwater chemistry indicate zones of steep nitrate concentration gradients associated with the feature.