<p>At a time when government agencies cite lack of funds for not restoring sewage-filled lakes, a study has indicated the high economic value of rejuvenating the water bodies (in the form of accumulated silt) in itself is enough to take up restoration. <br /><br /></p>.<p>A bathymetric survey and collection of water samples, along with efforts by researchers at the Indian Institute of Science (IISc) and Madras Engineer Group and active participation by citizens, revealed that the silt accumulated in Varthur and Bellandur lakes is worth Rs 1,800 crore. <br /><br />Contractors charge the government for de-silting the lakes and quietly earn additional revenue by selling it to a third party. However, this aspect remained unknown. The economic value of the silt has been highly underestimated. Money earned by selling silt could be used to restore the lakes, said Prof T V Ramachandra of IISc, who is leading the study. <br /><br />Varthur and Bellandur lakes were last de-silted in 1970. The bathymetric survey shows that a large quantity of silt has accumulated over the years in both the lakes, which together are spread over 1,000 acres. <br /><br />This blocks the natural process of ground water recharge, the professor said and recommended wet dredging to remove the silt and sludge as the first step towards rejuvenation. <br /><br />The silt could be used as manure to manufacture bricks and as an alternative to sand. Varthur and Bellandur lakes have about 7.3 million cubic metres worth of silt, which if removed will not only restore the lakes, but also address all the sand problems in the city, he said. <br /><br />Prof Ramachandra also said that before restoration, Jakkur lake was surrounded by about 300 borewells and had higher nitrate levels, but de-silting the lake improved ground water recharge and the next study found no nitrate traces in the borewell water. <br /></p>
<p>At a time when government agencies cite lack of funds for not restoring sewage-filled lakes, a study has indicated the high economic value of rejuvenating the water bodies (in the form of accumulated silt) in itself is enough to take up restoration. <br /><br /></p>.<p>A bathymetric survey and collection of water samples, along with efforts by researchers at the Indian Institute of Science (IISc) and Madras Engineer Group and active participation by citizens, revealed that the silt accumulated in Varthur and Bellandur lakes is worth Rs 1,800 crore. <br /><br />Contractors charge the government for de-silting the lakes and quietly earn additional revenue by selling it to a third party. However, this aspect remained unknown. The economic value of the silt has been highly underestimated. Money earned by selling silt could be used to restore the lakes, said Prof T V Ramachandra of IISc, who is leading the study. <br /><br />Varthur and Bellandur lakes were last de-silted in 1970. The bathymetric survey shows that a large quantity of silt has accumulated over the years in both the lakes, which together are spread over 1,000 acres. <br /><br />This blocks the natural process of ground water recharge, the professor said and recommended wet dredging to remove the silt and sludge as the first step towards rejuvenation. <br /><br />The silt could be used as manure to manufacture bricks and as an alternative to sand. Varthur and Bellandur lakes have about 7.3 million cubic metres worth of silt, which if removed will not only restore the lakes, but also address all the sand problems in the city, he said. <br /><br />Prof Ramachandra also said that before restoration, Jakkur lake was surrounded by about 300 borewells and had higher nitrate levels, but de-silting the lake improved ground water recharge and the next study found no nitrate traces in the borewell water. <br /></p>