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• HPT surveys at a site with K spanning nearly-seven orders of magnitude. • HPT reveals both sharp and gradual changes in K values across layer boundaries. • Integration of HPT-inverted K into HT yields better matches with permeameter K. • HPT K can help HT refine layer boundaries and capture intralayer K variability. Hydraulic profiling tool (HPT) and hydraulic tomography (HT) have been developed as promising techniques for the high-resolution characterization of surficial aquifer systems. HPT surveys can be rapidly conducted at a resolution of 1.5-cm, but provide only one-dimensional vertical profiles and require site-specific formulae to relate HPT measurements to K. Geostatistics-based HT can estimate three-dimensional distributions of hydraulic parameters, but may fail to provide detailed information and can be smooth when pumping/observation data density is sparse and usually are constrained to the area enclosed by the pumping and observation network. In this study, HPT and HT surveys were conducted at the North Campus Research Site (NCRS) in Waterloo, Ontario, Canada to characterize a glaciofluvial multi-aquifer-aquitard system with permeameter K values spanning nearly seven orders of magnitude. We first performed the geostatistical analysis of K values derived from 11 HPT surveys using the power-law model developed for the NCRS by Zhao and Illman (2022b). Then, the benefits of incorporating HPT K profiles into HT were evaluated for the reconstruction of hydraulic parameter fields. Results showed that the arithmetic mean of 11 HPT K profiles was nearly one order of magnitude higher than that of the 544 permeameter test K measurements. The K fields interpolated by ordinary kriging captured the vertical alternating layering patterns of aquifer and aquitard layers, while they over-predicted the values by nearly one order of magnitude than permeameter K for the top part of the aquifer system. By incorporating the kriged K values as prior means for the geostatistics-based HT, improvements were found in capturing spatial heterogeneity of K fields for areas both inside and outside the well cluster and in drawdown predictions than the inversion case using only pressure head data. The inclusion of vertical variation information of K derived from HPT into HT was also helpful in refining the vertical locations of estimated layer boundaries and introducing intralayer variation patterns of K for both aquifer and aquitard layers. This study demonstrates the potential ability of HT and HPT and advocates the joint use of both techniques for the characterization of subsurface heterogeneity at highly heterogeneous sites such as the NCRS. [ABSTRACT FROM AUTHOR]

• Inverse modeling approach proposed to invert cm-scale K from HPT surveys. • Based on inverted K , a new power-law model was developed for HPT surveys at NCRS. • The site-specific model predicted K values that correspond well with permeameter K. • Integrating HPT-inverted K into SSHT better defined sharp boundaries of a K field. Direct-push based hydraulic profiling tool (HPT) and geostatistically-based hydraulic tomography (HT) are two promising techniques for the high-resolution estimation of hydraulic conductivity (K) for unconsolidated sediments. Although HPT surveys could be conducted rapidly, relating the 1.5-cm resolution injection logging profiles to K always involve the upscaling of centimeter-scale measurements to coarser intervals for the development of site-specific formulae. On the other hand, K fields reconstructed by HT could be smooth when pumping test data are sparse. In this study, an inverse modeling approach was firstly utilized to estimate K values directly from HPT survey data for the glaciofluvial deposits at the North Campus Research Site (NCRS) in Waterloo, Ontario, Canada. A site-specific power-law relationship was generated for the NCRS to relate HPT profiles to the vertical distributions of K. Then, the proposed inverse modeling approach was evaluated with a two-dimensional synthetic aquifer under controlled conditions, and the estimated K profiles from inverse analysis of synthetic HPT surveys were incorporated into the steady-state HT. Results of the field study showed that K estimates from the developed formula corresponded better with K values from permeameter tests, than those estimated from the empirical model of McCall and Christy (2010) for HPT surveys. Moreover, through synthetic experiments, we demonstrated that integration of K values inverted from HPT into steady-state HT analyses yielded K tomograms that were significantly better than the geostatistical inversion results relying on pumping test data alone. Overall, this study highlights the need in developing site-specific formulae for the HPT and the joint implementation of HPT and HT techniques for the more cost-effective high-resolution characterization of subsurface heterogeneity. [ABSTRACT FROM AUTHOR]

• HPT pressure logs (P c) can be rapidly collected in unconsolidated deposits. • P c data provide information on sharp and gradually-varying layer boundaries. • Integrating HPT-derived hydrostratigraphy and HT yields a K field with sharp boundaries. • HPT K estimates require additional evaluations for highly heterogeneous deposits. Hydraulic tomography (HT) has been developed as a robust technique in characterizing subsurface heterogeneity over the last two decades. Hydraulic conductivity (K) and specific storage (S s) estimated by geostatistically-based HT inversion approaches are typically smooth and lack geological features when observation data density is sparse. Although integrating geological information can be helpful in adding structural features into parameter fields, costly efforts are required to obtain borehole logging through conventional coring and sampling. Also, identification of geological features such as layer boundaries from sampled materials can be a subjective process. In this study, corrected pressure (P c) logs collected during hydraulic profiling tool (HPT) surveys are utilized to derive the local hydrostratigraphic layers of the glaciofluvial deposit at the North Campus Research Site (NCRS) in Waterloo, Ontario, Canada. Site-specific geological models representing aquifer and aquitard layers are developed and calibrated to drawdown data of multiple pumping tests. Results show that estimated K fields correctly reflect the variation features of permeameter-estimated K profiles, as well as the spatial distribution of high and low K sediments. The calibrated geological models performed better than the geostatistically-based inversion approach in predicting independent pumping tests used for model validation. Moreover, by including K estimates of geological models as prior means, the estimated K fields reveal both intra- and interlayer heterogeneity, and the performances of drawdown prediction are further improved for the geostatistical inversion approach. Overall, our study suggests that, integration of stratigraphic information derived from HPT P c logs is useful for HT to capture the sharp boundaries in K fields, especially when the pumping test data is sparse. [ABSTRACT FROM AUTHOR]