Oral Presentation Australasian Groundwater Conference 2017

Anisotropy in hydraulic conductivity of jointed rocks – analytical and numerical interpretation of field measurements (#217)

Mahdi Zoorabadi 1 , Winton Gale 1 , Yvette Heritage 1
  1. SCT Operations Pty Ltd, Wollongong, NSW, Australia

Hydraulic conductivity of jointed rocks is controlled by conductivity of intact rock blocks and existing discontinuities. Rock discontinuities act as channels for water flow and their conductivity is relatively much higher than hydraulic conductivity of the intact rock. The geometry and inter-connectivity of discontinuity network induce variable hydraulic conductivity across various direction which called anisotropy in hydraulic conductivity. The common filed measurements which are done inside a single hole are not able to measure this behaviour properly. Interference tests which includes an injection or pumping out hole and several surrounding observation holes are the best techniques to measure the anisotropy in hydraulic conductivity. This paper presents applying the analytical and numerical models to interpret the interference test results to determine the anisotropy in hydraulic conductivity of jointed rocks. Papadepulos (1965) formulation is one of the common analytical methods to calculate the horizontal anisotropy of the hydraulic conductivity. This formulation needs injection or pumping flow rate and head changes at observation holes and can be directly apply to the test results. For 3D tensor of conductivity, the formulation which proposed by Hsieh & Neuman (1985) is common in practice. This study discuss the limitations of direct application of these two analytical methods and present a new procedure to apply them to calculate more reliable results. Additionally, 3D numerical modelling using FLAC3D was conducted as cross check to analytical models. Comparison between numerical modelling and analytical modelling shows that the proposed analytical procedure has high accuracy. Unlike numerical modelling, the proposed procedure is easy to apply and has capability to directly determine the storativity of the aquifer.

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  • We are offering awards for Career and Early Career presentations and posters. Please indicate length of time since highest degree completed.: 0 to 5 Years or currently studying