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