Comparison of alternative modelling approaches for groundwater flow in fractured rock

Selroos, Jan-Olof; Walker, Douglas D.; Ström, Anders; Gylling, Björn; Follin, Sven

doi:10.1016/s0022-1694(01)00551-0

Cited by 136 publications

(88 citation statements)

References 7 publications

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“…The influence of different model conceptualisations may be evaluated by having alternative conceptual models based on different geological interpretations (Selroos et al, 2001;National Research Council, 2001). Harrar et al (2003) and Højberg and Refsgaard (2005) present two different examples, both using three different conceptual models, based on three alternative geological interpretations for multi-aquifer system representative of eastern part of Denmark with glacial till plains (Højberg and Refsgaard, 2005) and in sandy outwash plains in the western part of Denmark (Harrar et al, 2003).…”

Section: What Is a Hydrogeological Conceptual Model?mentioning

confidence: 99%

Uncertainty in geological and hydrogeological data

Nilsson

Højberg

Refsgaard

et al. 2007

Hydrol. Earth Syst. Sci.

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Abstract. Uncertainty in conceptual model structure and in environmental data is of essential interest when dealing with uncertainty in water resources management. To make quantification of uncertainty possible is it necessary to identify and characterise the uncertainty in geological and hydrogeological data. This paper discusses a range of available techniques to describe the uncertainty related to geological model structure and scale of support. Literature examples on uncertainty in hydrogeological variables such as saturated hydraulic conductivity, specific yield, specific storage, effective porosity and dispersivity are given. Field data usually have a spatial and temporal scale of support that is different from the one on which numerical models for water resources management operate. Uncertainty in hydrogeological data variables is characterised and assessed within the methodological framework of the HarmoniRiB classification.

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Section: What Is a Hydrogeological Conceptual Model?mentioning

confidence: 99%

Uncertainty in geological and hydrogeological data

Nilsson

Højberg

Refsgaard

et al. 2007

Hydrol. Earth Syst. Sci.

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“…Choice of model type Studies of flow in fractured crystalline rocks have employed a wide variety of different conceptual and numerical models (Selroos et al 2002). Apart from porous medium and discrete fracture network models, lattice network models have sometimes been used to understand flow and solute transport behaviour in three dimensions.…”

Section: A Novel Lattice Network Modelmentioning

confidence: 99%

Groundwater flow into underground openings in fractured crystalline rocks: an interpretation based on long channels

Black¹,

Woodman

Barker

2016

Hydrogeol J

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Rethinking an old tracer experiment in fractured crystalline rock suggests a concept of groundwater flow in sparse networks of long channels that is supported by results from an innovative lattice network model. The model, HyperConv, can vary the mean length of 'strings' of connected bonds, and the gaps between them, using two independent probability functions. It is found that networks of long channels are able to percolate at lower values of (bond) density than networks of short channels. A general relationship between mean channel length, mean gap length and probability of percolation has been developed which incorporates the well-established result for 'classical' lattice network models as a special case. Using parameters appropriate to a 4-m diameter drift located 360 m below surface at Stripa Mine Underground Research Laboratory in Sweden, HyperConv is able to reproduce values of apparent positive skin, as observed in the so-called Macropermeability Experiment, but only when mean channel length exceeds 10 m. This implies that such channel systems must cross many fracture intersections without bifurcating. A general relationship in terms of flow dimension is suggested. Some initial investigations using HyperConv show that the commonly observed feature, 'compartmentalization', only occurs when channel density is just above the percolation threshold. Such compartments have been observed at Kamaishi Experimental Mine (Japan) implying a sparse flow network. It is suggested that compartments and skin are observable in the field, indicate sparse channel systems, and could form part of site characterization for deep nuclear waste repositories.

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“…The small networks usually comprise one to ten joints, so the application of a deterministic method is feasible, in which the position of joints is known (e.g. Tezuka & Watanabe 2000;Selroos et al 2002). In the case of larger networks, a hundred or more joints are considered, which may be generated using a stochastic approach (e.g.…”

Section: Models Of Impermeable Matrix and The Discrete Joint Network mentioning

confidence: 99%

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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Comparison of alternative modelling approaches for groundwater flow in fractured rock

Cited by 136 publications

References 7 publications

Uncertainty in geological and hydrogeological data

Uncertainty in geological and hydrogeological data

Groundwater flow into underground openings in fractured crystalline rocks: an interpretation based on long channels

Structural hydrogeology in the Kenogami uplands, Quebec, Canada /

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