New Delhi, Oct 8 (UNI) A joint study, carried out by the Central Ground Water Board and the states, has showed 839 overexploited zones in the country, where the groundwater extraction exceeds the annual replenishable resource observed during pre-monsoon and post-monsoon periods.
The latest study, carried out in 5,723 assessment units of the country have also showed that there were 226 'critical' units, where the groundwater development is above 90 per cent and within 100 per cent of annual replenishable resource and a significant decline is observed in the long-term water level trend in both the pre-monsoon and post-monsoon periods.
The study also showed that the 'dark or critical' blocks increased at a rate of 5.5 per cent during the mid-1980s to mid-1990s. If the trend continued at the same rate, a third of the blocks in the country would come in the 'grey' category within two decades.
Over 50 per cent of the 'dark blocks' were in the six states of Gujarat, Rajasthan, Haryana, Punjab, Tamil Nadu and Karnataka in 1995.
India has a tradition of using groundwater for agriculture, drinking and other domestic usages. However, with the advent of tubewells, the spread of irrigation and growth in urban areas, the state of groundwater deteriorated quickly. The commencement of intensive agriculture in the 60s has led to the exploitation of groundwater to such an extent that in areas like Mehsana in Gujarat and pockets of Punjab and Haryana it is now common for farmers to drill tubewells as deep as 500 m, often hitting the saline water beneath the freshwater aquifers.
Thus, while groundwater irrigation has been the mainstay of marginal farmers, water managers faced an enormous challenge in ensuring sustainable use of groundwater. The over-depletion of groundwater is becoming a major problem in many parts of the country, especially in urban areas.
Urban needs accounted for eight per cent of the total water consumption and water tables, around almost every town and city, were also falling, the report said.