Piece 2 - Hydrodynamic properties

How does water actually move through the fractured layer?

A fractured aquifer is not simply a porous medium with a few fractures.

At Maheshwaram, hydraulic tests at different scales were used to characterize the fractured-weathered layer. Slug tests, injection tests and pumping tests were interpreted using analytical approaches including double-porosity, anisotropic and fractional-flow models.

Key findings

Strong vertical anisotropy of hydraulic conductivity, with an average ratio close to 10.
Horizontal fractures play a major role in groundwater flow.
Fracture-network conductivity was estimated at approximately
2.1×10−52.1\times10^{-5} m/s.
Block conductivity was approximately
5.1×10−85.1\times10^{-8} m/s.
Thus, the fracture network is roughly 400 times more conductive than the blocks.
Effective porosity was estimated at 6.3×10−36.3\times10^{-3}.
Approximately 90% of storage was associated with the primary fracture network affecting the rock blocks, while the larger-scale secondary fracture network contributed about 10%.

[Gallery picture]

Fractures control transmissivity, while smaller-scale fracture networks contribute substantially to groundwater storage.