Geostatistics of the Borden Aquifer: High‐Resolution Characterization using Direct Groundwater Velocity Measurements

In 1986, a seminal data set from the Canadian Forces Base (C.F.B.) Borden aquifer, Ontario, Canada, was published, illustrating, in unprecedented detail, the spatial distribution of hydraulic conductivity (K). Among many contributions attached to that data set was a geostatistical examination of field-based data for comparison with theoretical predictions of macro-dispersivity. However, that work treated K as a static parameter and the sole source of flow variability. Here, point velocity probes (PVPs) are used to extend the earlier work by collecting a novel high-resolution data set of groundwater velocity (v) measurements in the C.F.B. Borden aquifer. Velocity is a dynamic parameter of fundamental importance, closely tied to solute dispersion. Over 400 velocity measurements were collected along a transect perpendicular to flow, analyzed geostatistically, and compared with the analysis of the B-B′ cross-section of K reported by Sudicky (1986), https://doi.org/10.1029/wr022i013p02069. The PVP measurements exhibited geostatistics similar to those previously estimated by Sudicky (1986), https://doi.org/10.1029/wr022i013p02069. This finding suggests, as implicitly assumed in the previous work, the distribution of v is primarily controlled by K. PVPs also provided a novel, high-resolution data set of groundwater flow directions. Since the ultimate objective of aquifer characterization includes the definition of velocity fields, this work not only extends the 1986 work, but also demonstrates a viable alternative for characterizing flow patterns in aquifers—with the advantage that direct v measurements reflect variability in porosity and hydraulic gradient, as well as K. This could ultimately be advantageous at sites with greater heterogeneity or other dynamic hydrogeological variabilities more pronounced than those at the Borden site.