GUWAHATI, Sept 16 – Guwahati and its adjoining areas are likely to suffer a crisis in the form of groundwater depletion, if efforts are not made to optimise the use of the resources. Both State Government and citizens must take steps that would help recharge groundwater, which has been exploited at a worrying rate. Noted geologist Dr Pranavjyoti Deka told this to The Assam Tribune, adding that groundwater of Assam needs to be mapped and a comprehensive plan about its use should be prepared. The issue has gained currency with recent scientific announcements indicating that rainfall in Assam and other parts of the North East is likely to decrease due to climatic changes. Substantial reduction of rainfall would contribute to less water reaching underground aquifers. Well acquainted with the geologic formations of Guwahati and adjoining areas, Dr Deka said that the region’s groundwater is recharged by two major sources – rainfall and the river Brahmaputra. Any decrease in rainfall will lower the groundwater level in areas where the chief source is rainfall. There are many areas, he asserted, where the Brahmaputra cannot recharge the groundwater due to the character of sediments or distance from the source. Many of the channels, which were earlier linked to the Brahmaputra, have been blocked and others have dried up, he pointed out. The absence of these channels has also lessened the scope of groundwater recharge. Dr Deka said the State Government must come up with legislation to halt the unplanned exploitation of groundwater, and take steps to ensure that highrise buildings cannot simply go on extracting the resource at will. “The Government must ensure that highrise buildings which rely on groundwater have recharge units,” he remarked. He favoured a cap on the volume of groundwater that highrise buildings can extract, so that the valuable resource is not wasted. In many areas, wells and ordinary tubewells have run dry as nearby high-rises continue to draw groundwater in huge amounts. Conservation and maintenance of natural and man-made water bodies, he believes, is another priority for protecting groundwater resources. Depletion of such features will constrain key sources of groundwater recharge. Change in land use has also added to the concerns over groundwater. Loss of vegetative cover has increased the rate of surface run-off, which in turn reduces percolation of water to the ground below. This problem is acute in the hilly terrain in and around the city, where more surface run-off has also resulted in erosion and deposition of soil in low-lying areas.