Geology Reference
In-Depth Information
9
Upscaling of Slug Test Hydraulic
Conductivity Using Discrete
Fracture Network Modelling in
Granitic Aquifers
Dominique Bruel, Faisal K. Zaidi
1
and C. Engerrand
Centre de Géosciences, Ecole des Mines de Paris
35 rue St Honoré, 77300 Fontainebleau, France
1
NGRI, Uppal Road, Hyderabad-500 007, India
INTRODUCTION
The Indian sub-continent is underlain by hard rocks aquifers that are devoid
of primary porosity and occupy more than two thirds of the landmass. These
aquifers are highly vulnerable to pollution and resource depletion because
they are the most heavily exploited by the population for agriculture, industry
and domestic needs. These hard rocks aquifers, in general, consist of three
layers: the weathered zone that can be considered as a porous media, the
fissured/fractured zone, which is heterogeneous, and the fresh basement
which is generally devoid of any openings unless and until some deep seated
tectonic fractures are present. Aquifers in such geological settings are,
therefore, of very variable quality, inherently to the heterogeneous nature of
the fracture networks. Due to the adaptation of the latest drilling technology
in India during the last few decades, ground water has been exploited on a
large scale. But this uncontrolled exploitation of the resource has resulted in
an alarming decline in water levels. The characterization of the flow and
storage of ground water in these systems is a challenging task since flow and
transport processes are very different from those occurring in the porous
matrix. Furthermore there is an extremely high degree of contrast between
the hydraulic conductivity of the fractures within short distances. An
estimation of the groundwater resources is only possible through an estimation
of flow and storage parameters in the fracture systems but it is anticipated
that the responses of pumping tests performed in well field cannot be analyzed
through classical aquifer-testing methods that assume a homogeneous aquifer.
