BENGALURU: In Sarjapur and surrounding areas, borewells going deeper than 600feet which are not sources of large amounts of water, are not sustainable. Instead, investing in recharge wells might be a better alternative.
This was revealed during a three-year programme called the `participatory aquifer mapping process' in eight urban micro-watersheds on the Bellandur-Sarjapur Road, spanning about 33sqkm, by Wipro Technologies along with Biome Environmental Trust and Advanced Centre for Water Resource Development and Management (ACWADAM).
The highlights of the assessment, revealed on Friday at a meeting of all stakeholders and residents said: The Total Dissolved Salts (TDS) found in borewell water is higher than that found in shallow, open well water. "The cost of treating water is higher in the case of borewell water, compared to open well water," said Avinash Krishnamurthy of Biome.
"People are averse to using open wells, as they believe the deeper you dig, the cleaner the water. Due to this, over two decades, there has been a shift from using shallow wells to borewells. The likelihood of striking water is higher in shallow wells than in borewells," said Himanshu Kulkarni of ACWADAM. The area has about 30 old, open irrigation wells, some of which were wet.
The team spoke with all stakeholders involved: welldiggers, plumbers, people and communities who owned and used these wells. They surveyed more than 200 wells.
Traditionally, lakes have been discharge points, but a study of the shallow wells along the north side of Kaikonderahalli lake for a year found that the lake functioned both as a recharge and discharge point.During the monsoon, it func tions as a discharge point by recharging shallow wells nearby. However, in drier months, the lake functions as a recharge zone, and begins to receive water from the shallow wells.
"The lake seems to be recharging shallow aquifers. However, borewells around the lake appear to be dry, so rejuvenation of lakes has not necessarily resulted in high yield from neighbouring borewells," said Shubha Ramachandra of Biome."Three or four shallow wells and irrigation wells around the lake yield 40,000-50,000 litres of water a day . For shallow aquifers to be recharged, recharge wells must be dug."