PUNE: Groundwater recharge and movement is dependant on the structure of soil beneath ground level, along with the amount of rain and percolation area available, states a geological and topographical study. While the state provides 40 per cent of flat terrains for percolation of rain water, there is presence of 82 per cent of hard basalt rocks in the sub-structures, which block groundwater recharge and movement.
Pune city lies in the basalt rock area which has low porosity, resulting in just 10 per cent of rain water percolation. “The city has a varied ground water level where the main areas of Swargate, Satara Road, Tilak Road and the neighbouring areas have groundwater at 1 to 2 meter from the ground level. Fringe areas such as Baner, Pashan, Undri and NIBM Road have ground water at 6 to 7 meter deep,” said Suresh Khandale, additional director of Groundwater Surveys and Development Agency (GSDA). The rain water harvesting systems to recharge groundwater are suitable to gradually increase the level. Fringe areas have an alternate option of using surface tanks to tap rain water.
Where urban areas are considered to have low rain water percolation due to paving of soil and concrete roads, there is a lower water dip in groundwater level observed here. “Due to excessive use, over 100 villages around the city have a groundwater level dip of more than one meter even after a rain water percolation rate of more than 10 per cent. Also, the urban areas have basalt structures weathered over time, providing areas for groundwater movement while rural areas have hard primary structures,” said Dilip Satbhai, a city based hydrologist. He also added that utilisation of ground water has risen by 50 times in the rural areas in the past 10 years.
As citizens face water shortage, artificial groundwater recharge methods such as rain water harvesting are in need for both urban and rural areas. “In a city like Pune, roof-top rain water harvesting is a popular concept, especially for recharging bore wells. However, restricting the use of water could be more effective. There must be a balance in the conservation and utilization to sustain natural resources like groundwater,” added Satbhai.