The role of in situ stress in determining hydraulic connectivity in a fractured rock aquifer (Australia)

Mortimer, L.; Aydın, Adnan; Simmons, Craig T.; Heinson, Graham; Love, Andrew J.

doi:10.1007/s10040-011-0760-z

Cited by 16 publications

(6 citation statements)

References 36 publications

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“…For all these processes, hydraulic conductivity of geological formation plays a vital role in the movement of fluids, which depends on the secondary features like fractures and fissures and their length, density, orientation, etc. in particular in the hard rock regions (Mortimer et al 2011). …”

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Search for hydraulic connectivity between surface reservoirs and surrounding aquifers in the reservoir-triggered seismic environment (Koyna region, India) using hydrochemical and isotopic signatures

Reddy

Nagabhushanam

2015

J Seismol

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Triggered seismicity is an accepted hypothesis in the present days. However, detailed hydrogeological investigations are lacking in the well-known reservoirtriggered seismic (RTS) zones. Here, we made an attempt to understand the direct linkage between the well-known Koyna-Warna reservoirs believed to be under the RTS zone (situated in the Deccan volcanic province (DVP), India) and the surrounding groundwater system up to 250 m deep from the ground surface. Seismic activity in the region started soon after the impoundment of water in the Koyna reservoir and being continued over the last four and a half decades. Though researchers have carried out numerous studies on the Koyna seismicity, no hydrogeological investigations were attempted. Hence, hydrogeological, hydrochemical, and isotopic investigations were carried out for 7 years on groundwaters from 15 deep bore wells (up to 250 m) and two surface reservoir waters to elucidate the direct hydraulic connectivity between them. No appreciable seasonal change was observed in piezometric heads of the artesian wells, but the semi-artesian wells did show fluctuation of~2 to 12 m during different years, which did not have any relation with the reservoir water levels. No considerable seasonal change in hydrochemistry was observed in individual wells due to the confined nature of the aquifers. The hydrochemical and δ 18 O data of the studied deep groundwaters and reservoir waters, being different from each other, rule out the possibility of direct hydraulic connectivity between them and surrounding groundwater (up to 250 m), even though favorable topographic conditions exist for linkage. The radiocarbon ages, being incomparable between different well waters, support the inference drawn from hydrochemistry and stable isotope data.

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confidence: 98%

Search for hydraulic connectivity between surface reservoirs and surrounding aquifers in the reservoir-triggered seismic environment (Koyna region, India) using hydrochemical and isotopic signatures

Reddy

Nagabhushanam

2015

J Seismol

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“…The stress field may be considerably influent over the fluid control patterns, especially in fractured rocks with low matrix permeability (Mortimer et al 2011b), as the regional stress state controls joint apertures and the potential reactivation of existing fractures (Henriksen & Braathen 2006). Therefore, the conductivity of a particular joint varies with its orientation in the in situ stress field (Henriksen & Braathen 2006): the flow occurs preferentially along joints that are normal to the minimum principal stress (a 3 ) direction, due to low normal stress (Mortimer et al 2011b), or inclined (around 30°) to the maximum principal stress (ai) direction, due to dilatation (Mortimer et al 2011b).…”

Section: Lineament Map Within the Tpis (Intramunicpal Public Territormentioning

confidence: 99%

“…Therefore, the conductivity of a particular joint varies with its orientation in the in situ stress field (Henriksen & Braathen 2006): the flow occurs preferentially along joints that are normal to the minimum principal stress (a 3 ) direction, due to low normal stress (Mortimer et al 2011b), or inclined (around 30°) to the maximum principal stress (ai) direction, due to dilatation (Mortimer et al 2011b). Moreover, joint permeability might be expected to be more stress-dependent at shallow depths (up to 200m), at which groundwater is usually extracted (Mortimer et al 2011b). …”

Section: Lineament Map Within the Tpis (Intramunicpal Public Territormentioning

confidence: 99%

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Structural hydrogeology in the Kenogami uplands, Quebec, Canada /

Silva¹

2012

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Characterizing the joint system is a very significant component of investigations on fractured rock aquifers, as the secondary porosity controls the groundwater flow. It is also important to analyze the types of interactions between the joints, e.g., the types of termination and the dominancy of a certain joint set, since such information helps to understand the tectonic events that were responsible for the generation of the joint systems in the aquifer. Moreover, the current stress field is usually the most significant in controlling joint aperture, which plays a major role in groundwater flow.The main objective of this work is to characterize an aquifer in fractured crystalline rocks with a fairly homogeneous lithology, defining a hydrogeological model of the study area, through structural surveys at different scales and hydrogeologic data analyses. This study was carried out in the Kenogami uplands, within the Saguenay graben, Quebec. It aimed to answer the following questions: (1) is there a structured joint system in the bedrock, that is, is it possible to identify preferential joint orientations and structural domains? (2) Can joint systems be defined at different scales, e.g. regional and local scales? If yes, are there any relationships between the systems observed at different scales? (3) Can any correlation between the joint system(s) and the past and present stress fields be identified? (4) Is there a relationship between the hydrogeological properties obtained from boreholes and the joint system(s)?The structural survey involved three main phases. First, a characterization at the regional scale of the joint system is derived from air photo interpretation, lineament analysis, and a general field survey at selected sites. The latter involves the investigation IV of the spatial distribution of the main joint sets, and the study of the relative ages of joint sets and past stress field components conducted on horizontal outcrops. Second, a detailed structural survey of selected road cuts was carried out to define and characterize the main joint sets that compose the joint system in the study area. Third, the realization of geophysical borehole logging provided valuable information at depth, especially regarding subhorizontal joint sets. These steps allowed to answer the questions proposed in the beginning of this research.This project allowed the characterization of an aquifer in fractured crystalline rocks, regarding the following aspects: joint systems at different scales, past stress fields, hydraulic properties and the possible relationships between these parameters. The methodology adopted may be applied to other studies on fractured rock aquifers.Finally, a conceptual model was developed for the fractured rock aquifer in the Kenogami uplands, using the unit block approach. This model may be extrapolated to a regional scale, and it reflects the predominance of the subvertical joints in the study area.Other contributions from this work include the introduction of procedures for applying Terzag...

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“…Structural elements such as fault zones also strongly govern the behaviour of these systems (Forster & Evans 1991;López & Smith 1995;Bense et al 2013). The nature, abundance, orientation and connectivity of these water-bearing features are largely governed by the history and nature of structural deformation of the bedrock, and commonly impose strong anisotropic flow and transport parameters on these bedrock aquifers (Hsieh et al 1985;Bour & Davy 1997;Mortimer et al 2011). Weathering processes furthermore lead to an alteration of bedrock composition and associated aquifer properties resulting in enhanced fracture connectivity and an overall vertical stratification/ zonation of bulk aquifer properties, ranging from highly altered shallow regolith horizons to more competent sparsely fractured bedrock at depth (Dewandel et al 2006;Krásný & Sharp 2007;Lachassagne et al 2011).…”

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Groundwater in fractured bedrock environments: managing catchment and subsurface resources – an introduction

Ofterdinger

MacDonald

Comte

et al. 2019

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The role of in situ stress in determining hydraulic connectivity in a fractured rock aquifer (Australia)

Cited by 16 publications

References 36 publications

Search for hydraulic connectivity between surface reservoirs and surrounding aquifers in the reservoir-triggered seismic environment (Koyna region, India) using hydrochemical and isotopic signatures

Search for hydraulic connectivity between surface reservoirs and surrounding aquifers in the reservoir-triggered seismic environment (Koyna region, India) using hydrochemical and isotopic signatures

Structural hydrogeology in the Kenogami uplands, Quebec, Canada /

Groundwater in fractured bedrock environments: managing catchment and subsurface resources – an introduction

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