Redundant and Nonredundant Information for Model Calibration or Hydraulic Tomography

Abstract

Drawdown data from independent pumping tests have widely been used to validate the estimated hydraulic parameters from inverse modeling or hydraulic tomography (HT). Yet, the independent pumping test has not been clearly defined. Therefore, the goal of this paper is to define this independent pumping test concept, based on the redundant or nonredundant information about aquifer heterogeneity embedded in the observed heads during cross-hole pumping tests. The definition of complete, moderate redundancy and high nonredundancy of information are stipulated using cross-correlation analysis of the relationship between the head and heterogeneity. Afterward, data from numerical experiments and field sequential pumping test campaigns reinforce the concept and the definition.

Potential of Hydraulic Tomography in Identifying Boundary Conditions of Groundwater Basins

“…The numerical results also signify the advantages of HT surveys over multiple simultaneous pumping tests in capturing groundwater basins' true boundary conditions and in producing a higher‐resolution characterization of subsurface heterogeneity. These results corroborate that HT surveys collect nonredundant information (Wen et al, 2020), critical for inverse modeling of groundwater problems.…”

“…The responses collected during each stress at a different location are tantamount to a snapshot of aquifer heterogeneity from a different angle and perspective. In other words, each snapshot carries non-fully redundant information (Wen et al, 2020) and leads to an estimate of the spatial distribution of aquifer properties, and it is then cross validated and updated with a new snapshot. Consequently, synthesizing the multiple sets of aquifer signals to characterize spatial patterns of hydraulic parameters in the subsurface results in higher accuracy than conventional aquifer tests.…”

Multiscale Hydraulic Conductivity Characterization in a Fractured Granitic Aquifer: The Evaluation of Scale Effect

“…As shown in Table 3, even though the pumping location is fixed at BW6, estimates from either analytical or least squares methods change with different combinations of three observation boreholes from the four. Such a change in the estimate due to the change of one of the three observation boreholes signifies the explanation of THT's logic by Wen et al (2019). That is, adding a new observation borehole provides new information about heterogeneity to THT analysis.…”

Identification of groundwater basin shape and boundary using hydraulic tomography

“…Thus, HT allows us to gather non-redundant information of the aquifer from a limited number of wells. The collection of non-redundant information can improve the estimation of heterogeneity (Wen et al, 2019). This improvement has also been validated by many experiments of HT in synthetic aquifers, laboratory sandboxes, and field operations (e.g., Yeh and Liu, 2000;Liu et al, 2002;Zhu and Yeh, 2005;Liu et al, 2007;Straface et al, 2007;Ni et al, 2009;Yin and Illman, 2009;Bohling and Butler, 2010;Wen et al, 2010;Cardiff and Barrash, 2011;Huang et al, 2011;Berg and Illman, 2012;Cardiff et al, 2012;Illman et al, 2015;Tso et al, 2016;Zha et al, 2016).…”