Effect of discontinuous aquitard on the seepage from a static water body - A research report by National Institute of Hydrology

In this study, the influence of a discontinuous aquitard on the seepage from a recharge source in a multilayered aquifer system, with the prescribed hydrogeological set-up, has been subjected to investigation.

For the purpose of investigation, a case study with recharge and discharge sources in a two layer aquifer system separated by a barrier with possible discontinuities is considered. A three-dimensional groundwater flow model is employed for simulating flow in the system. The recharging source (pond or lake) is positioned at the centre of the aquifer system in plan. 

A number of cases have been studied by making openings of varying widths in the aquitard, symmetrically located below the recharge-source to analyze the impact of a discontinuity on seepage distribution. The report deals with the influence of the dimensions of the opening in the aquitard and the aquifer characteristics on the discharge as well as on the hydraulic potentials.

The distribution of hydraulic potential in the entire system for different diffusivity values and for various aquitard openings is analyzed. A number of cases were studied and results are presented graphically.

The study revealed that of the various aquifer parameters diffusivity has significant effect on the efficiency of recharge pond. Also, it is observed that even a minor discontinuity in the barrier causes significant change in the seepage pattern.

Further studies are envisaged by incorporating aspects like:

• eccentricity of the discontinuities;
• positioning of the flow barrier;
• a range of values for head-causing flow;
• changing boundary conditions;
• changing aspect ratios of the system;
• non-uniform or transient recharge from the source.

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