Artificial recharging of an unconfined aquifer with an injection well in Ghataprabha sub-basin– A research report by National Institute of Hydrology

The report deals with the artificial recharging of an unconfined aquifer with injection well in the Hukkeri taluka in Ghataprabha sub-basin of Krishna river. The Ghataprabha sub-basin of Krishna like most river basins of peninsular India has been facing groundwater development problems varying in nature and severity. It has got a wide spectrum of issues such as cases of failure of wells at several places on the one hand, while some areas becoming unfertile due to waterlogging.

The Hukkeri taluk in the Ghataprabha sub-basin has been experiencing depletion of its aquifers for a number of years. The problem has been investigated through mathematical modeling techniques and plausible measures for recharging the aquifers have been evolved.

The increased dependence and utilization of groundwater has caused depletion of aquifers in many parts of the country. Artificial recharge methods using percolation tank, injection wells and spreading basins have been proposed and implemented to certain extent in order to resuscitate the depleting groundwater resources.

The important issues associated with artificial recharge are the nature of the rechargeable water source, the system of recharge to be used, the expected injection rates, the hydraulic response of the system to injection and the management of the injected water as part of the total water resources system. Mathematical modeling is a powerful tool in the investigation of artificial recharge processes and evaluation of viable strategies.

In order to address local-scale groundwater issues, a calibrated three dimensional regional finite difference model, based upon the United States Geological Survey (USGS) modular three-dimensional finite difference groundwater flow model MODFLOW, generated for the Ghataprabha sub-basin has been used as a basis for the local scale modeling of the Hukkeri region, which has been experiencing drying of open and borewells in recent times.

The generated microscopic model with finer mesh is calibrated and validated using MODFLOW. Various options of artificial recharge measures have been tried out with the calibrated model and results analyzed. Analysis of the results shows that maintaining a higher water-level in the Ghataprabha river reach in the downstream of Hidkal Dam and in the Hiranyakeshi tributary is the best option for maintaining a reasonable water table depth in the area.

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