strategy , known as GARDIT ( General Aquifer Research Development and Investigation Team ) strategy that aimed to deliver an increase in withdrawal of 70 million lit / day , using this water for public and private supply , and to bring G . W . levels under control . There has been a more rapid decline in G . W . levels in the central and southeast London than expected , caused restriction of withdrawal Govt . Chennai :
The Ground water problem in Chennai is opposite . Chennai is underlain by various geological formations from ancient Archaean to the Recent Alluvium . Ground water in Chennai district occurs in all the geological formations viz ., the Archaean crystalline , Gondwanas , Tertiaries and alluvium . The crystalline rocks are weathered and jointed / fractured . The degree and depth of weathering varies from place to place and the thickness of weathered mantle varies from less than a meter to about 12 m in this district . The successful bore wells drilled tapping the deeper fractured aquifers in Saidapet , Adyar , Kasturba nagar , Gandhi nagar and Ashok nagar revealed the existence of fracturing down to depth of 60 m below ground level . The granular zones below the Kankar layer in the depth range of 20-28 m bgl in Poes Garden probably represent Tertiary sandstones and tube wells tapping these granular zones yield 2 to 3 lps . The C . P . R Environmental Educational Centre made a survey in and around Chennai city , and the results show that crisis in both water availability and pollution is worsening gradually with each day . On one hand , the quality of water is getting worse , and on the other hand , the level of water level is going down rapidly . Water samples from different locations were collected from wells and boreholes and analyzed for their portability . Total dissolved Solid ( TDS ) exceeded 500 mg / l ( desired limit in drinking water ) in 83 % of samples , and 72 % of samples contained more than 1000mg / l . About 38 % of samples contained more than 2000 mg / l of TDS , and 22 % of samples contained high level of iron content . Proper water resource management and rainwater harvesting may reduce the problem .
6
Integrated River Basin Management Society