Considering the potential effect of faulting on regional-scale groundwater flow: an illustrative example from Australia’s Great Artesian Basin

Flowing wells: terminology, history and role in the evolution of groundwater science

“…In his book about flow systems, Tóth (2009) states that since the 1960s, hydrogeology's basic paradigm has shifted from confined flow in aquifers (aquitard-bound flow) to cross-formational flow in drainage basins, i.e., flow paths change from through a confined aquifer to across aquitards and different depths of aquifers in heterogeneous basins. Although cross-formational flow (inter-aquifer leakage) had already been anticipated by Chamberlin (1885), it was identified in the Dakota artesian basin through aquitards in the 1960s (Swenson, 1968), and it was recently identified in the Great Artesian Basin through faults (Pandey et al, 2020;Smerdon and Turnadge, 2015). Moreover, although the concept of flowing wells in the context of aquitard bounding is introduced in almost every groundwater textbook, the concept of unconfined-flow flowing wells in homogeneous basins has been included in few textbooks (Domenico and Schwartz, 1998;Freeze and Cherry, 1979;Heath, 1983;Kasenow, 2010;Lohman, 1972b).…”

Identifying groundwater compartmentalisation for hydraulic fracturing risk assessments

“…Groundwater compartmentalisation is important for determining the potential migration routes and receptors of fracking fluid contaminants because it can create groundwater flow directions different to regional trends. 22,23 Where basins and groundwater flow extend across multiple jurisdictions this could be important because each jurisdiction may have different groundwater management legislation. 23 Compartmentalisation is also important because it can discourage lateral groundwater flow and encourage upward flow in the presence of a vertical head gradient.…”

“…22,23 Where basins and groundwater flow extend across multiple jurisdictions this could be important because each jurisdiction may have different groundwater management legislation. 23 Compartmentalisation is also important because it can discourage lateral groundwater flow and encourage upward flow in the presence of a vertical head gradient. 14 A compartmentalised basin may therefore create compartments with higher vulnerabilities to contamination because regional lateral groundwater flow cannot dilute any fracking fluid contaminants.…”

“…This effect is hypothesised to be greatest when faults strike perpendicular to the regional flow direction, thereby creating areas of reduced or no flow. 23 Conversely, isolated compartments could prevent the regional movement of contaminants; contaminants would be restricted to the compartment they originate from, thereby protecting surrounding aquifers in neighbouring compartments. 17 For the Bowland Basin we identified a number of possible examples of compartmentalisation, suggesting that areas of the Bowland Basin are compartmentalised.…”

“…17 Compartmentalisation can induce flow directions different to regional trends, create areas of no flow or reduced flow, and produce large variations in groundwater levels, temperatures and compositions. [21][22][23] All these effects have implications for groundwater abstractions, fluid injections, and the potential subsurface movement of contaminants. Consequently, there is a need to be able to adequately identify groundwater compartmentalisation for environmental risk assessments of fracking operations.…”