The effect of low‐permeability fault zones on groundwater flow in a compartmentalized system. Experimental evidence from a carbonate aquifer (Southern Italy)

Abstract

The hydrogeological behaviour of fault zones in carbonate aquifers is often neglected in conceptual and numerical models. Furthermore, no information is available regarding the relationships between piezometric levels when significant compartmentalization occurs due to the occurrence of low‐flow fault zones. The aim of this study was to refine the conceptualization of subsurface flow in faulted carbonate aquifers and to analyse relationships between sub‐basins within a compartmentalized aquifer system in Southern Italy. The interactions between compartments that straddle low‐flow faults were investigated over four hydrologic years using a statistical approach to compare (i) the hydraulic heads within two wells located up‐ and down‐gradient of tectonic discontinuities as well as (ii) the rainfall and piezometric levels. The results of this study suggest that a set of barriers exists between the wells, and, therefore, the total head loss observed between the wells (approximately 80 m) should be distributed across several aquitards, with one aquitard exhibiting a relatively high permeability or low degree of integrity. Due to slight differences in permeability, transient conditions in aquitards can occur over relatively short periods, which is in agreement with the results of the statistical data analysis. Consequently, rather than being caused by pure aquitards, aquifer system compartmentalization likely results from slight differences in the permeability between lower‐permeability fault zones and adjacent higher‐permeability protoliths. Copyright © 2014 John Wiley & Sons, Ltd.

Integrating Hydrogeological and Microbiological Data and Modelling to Characterize the Hydraulic Features and Behaviour of Coastal Carbonate Aquifers: A Case in Western Cuba

“…On the contrary, taking into account the increase of the hydraulic gradient from 0.02% (far from the fault zones) to 1.9-4.2% (close to the fault zones) along the south-western edge of the test site, it seems that a lower-permeability fault core is associated to the local fault zones, which partially impedes fluid flow, causing the gradient to locally rise. This relationship between hydraulic gradient increase and lower-permeability fault core is in agreement with the results of experimental studies carried out in other carbonate aquifers, fissured and karstified, where the groundwater flow lines are approximately orthogonal to the direction of the fault core [36][37][38][39][40][41][42][43].…”

Hydrogeological Behaviour and Geochemical Features of Waters in Evaporite-Bearing Low-Permeability Successions: A Case Study in Southern Sicily, Italy

“…As expected, taking into consideration previous studies in similar geologic settings [16], the studied system is characterised by vertical and discontinuous heterogeneity [81], caused by various factors such as (i) the coexistence of different geological formations, (ii) their folded regular sequence, and (iii) the fractured (karstified) evaporitic intrastrata/lenses that locally increase the bulk permeability of the low-permeability system. In contrast with other heterogeneous systems, no fault zones influence fluid flow, neither enhancing [82][83][84] nor partially or totally impeding it [85][86][87].…”

Hydrogeology of continental southern Italy

“…The knowledge about the hydrogeological features of these aquifers greatly improved due to studies for the construction of the main tunnels and tapping works in southern Italy (Celico, 1978(Celico, , 1983. The hydrogeological conceptual models proposed for these aquifers (Aquino, Petrella, Florio, Celico, & Celico, 2015;Celico, 1983;Celico, Celico, De Vita, & Piscopo, 2000;Celico, Petrella, & Celico, 2006;Celico et al, 2010;Fiorillo, 2011;Petrella, Aquino, Fiorillo, & Celico, 2015;Petrella, Capuano, Carcione, & Celico, 2009) identified strong similarities and differences with those of similar aquifers in other zones of the world (Drogue, 1992;Goldscheider & Drew, 2007;Jeannin, 1998;Kiraly, 1975Kiraly, , 2002Klimchouk, 2000;Mangin, 1975;White, 1969White, , 2002.…”