The Times of India 06.04.2013
Tamil Nadu faces 11% water deficit, stares at acute crisis: Study
CHENNAI: Tamil Nadu is facing a water deficit
of 11%, says a report. This is bad news, coming as it does at the
beginning of a torrid summer. While the current total water demand in
the state, for domestic, irrigation, livestock and industrial needs, is
1,867.85 tmcft (thousand million cubic feet) a year, the total
availability, from all resources, is only 1,681.78 tmcft.
This deficit will rise to 17% by 2045, said the report, jointly prepared by several central and state government agencies, including Tamil Nadu's public works department and the Central Water Commission.
Water experts say a 11% deficit at present means that the state is set for an acute water crisis in the coming years, and blame the situation on the lack of serious conservation efforts.
Experts who helped to conduct the study said that the overflows into the sea during the monsoon can alone meet the drinking water requirement of the entire state. The excessive extraction of groundwater in the coastal areas has resulted in sea water intrusion, the report said. Extraction of groundwater has increased manifold in Chennai, Cuddalore, Chidambaram, Nagapattinam and Tuticorin districts, where industrial and institutional activities have increased and population has shot up, it said. As per a recent classification, 139 revenue blocks, one third of the total blocks in the state, have recorded overexploitation of groundwater.
"These findings are not surprising," said Prof S Janakarajan, a water expert with the Madras Institute of Development Studies. "Apart from agricultural use, there is a rise in demand for water due to urbanization and industrial development," he said. "River aquifers have lost their capacity to recharge due to excessive sand mining. This has resulted in huge overflows into the sea during the monsoon," he said, suggesting that water bodies be restored to store the surplus flows during heavy rain.
Tamil Nadu, which had three reservoirs in the pre-independence era, has added 82 reservoirs in the last six decades and boasts of 39,200 tanks now. At least 17,879 of them, big and small, are on the coastal belt, and their status is either 'good' or 'normal'. But an alarming 80% of overflows from rivers is wasted, said the report based on a study on 'Effective utilization of northeast monsoon'.
The report has proposed 13,560 crore for works in the next decade to rectify the system. About 130 tmcft of water flows into the sea from at least 10 rivers, including the Cauvery, it said. Compare this to Chennai's drinker water needs -- 1 tmcft every month.
Sedimentation has reduced the capacity of several reservoirs between 2% and 59%. Built in 1934, Mettur reservoir, the lifeline of Cauvery delta, loses 11 million cubic metres of storage capacity a year due to sedimentation. The water tanks lose 40 to 50 million cubic metres of storage capacity each year. The report emphasised the need for consistent efforts to desilt water bodies. The silt can be used either for construction, agriculture or river restoration, it said.
"Thanks to the new reservoirs and better management of water tanks in parts of the state, either by PWD or local bodies, the deficit could be managed over the years. But the demand is shooting up every year," said a water manager. The report suggested it would be prudent to link the rivers within the state by short canals to divert the occasional flood flows to the adjoining basins. The state often witnesses a situation in which one river is in spate and other is bone dry.
The state will now be compelled to augment the capacity of existing storage structures in coastal regions, construct check dams and new reservoirs, and link rivers, wherever possible, as suggested by the report.
"Unless this is done, the future looks pretty bleak. With a majority of the rivers being interstate, dependence on neighbouring states should end," a member of the study team said. The good news is that the 41-year data shows there is no dramatic change in the trend in the onset of northeast monsoon.
This deficit will rise to 17% by 2045, said the report, jointly prepared by several central and state government agencies, including Tamil Nadu's public works department and the Central Water Commission.
Water experts say a 11% deficit at present means that the state is set for an acute water crisis in the coming years, and blame the situation on the lack of serious conservation efforts.
Experts who helped to conduct the study said that the overflows into the sea during the monsoon can alone meet the drinking water requirement of the entire state. The excessive extraction of groundwater in the coastal areas has resulted in sea water intrusion, the report said. Extraction of groundwater has increased manifold in Chennai, Cuddalore, Chidambaram, Nagapattinam and Tuticorin districts, where industrial and institutional activities have increased and population has shot up, it said. As per a recent classification, 139 revenue blocks, one third of the total blocks in the state, have recorded overexploitation of groundwater.
"These findings are not surprising," said Prof S Janakarajan, a water expert with the Madras Institute of Development Studies. "Apart from agricultural use, there is a rise in demand for water due to urbanization and industrial development," he said. "River aquifers have lost their capacity to recharge due to excessive sand mining. This has resulted in huge overflows into the sea during the monsoon," he said, suggesting that water bodies be restored to store the surplus flows during heavy rain.
Tamil Nadu, which had three reservoirs in the pre-independence era, has added 82 reservoirs in the last six decades and boasts of 39,200 tanks now. At least 17,879 of them, big and small, are on the coastal belt, and their status is either 'good' or 'normal'. But an alarming 80% of overflows from rivers is wasted, said the report based on a study on 'Effective utilization of northeast monsoon'.
The report has proposed 13,560 crore for works in the next decade to rectify the system. About 130 tmcft of water flows into the sea from at least 10 rivers, including the Cauvery, it said. Compare this to Chennai's drinker water needs -- 1 tmcft every month.
Sedimentation has reduced the capacity of several reservoirs between 2% and 59%. Built in 1934, Mettur reservoir, the lifeline of Cauvery delta, loses 11 million cubic metres of storage capacity a year due to sedimentation. The water tanks lose 40 to 50 million cubic metres of storage capacity each year. The report emphasised the need for consistent efforts to desilt water bodies. The silt can be used either for construction, agriculture or river restoration, it said.
"Thanks to the new reservoirs and better management of water tanks in parts of the state, either by PWD or local bodies, the deficit could be managed over the years. But the demand is shooting up every year," said a water manager. The report suggested it would be prudent to link the rivers within the state by short canals to divert the occasional flood flows to the adjoining basins. The state often witnesses a situation in which one river is in spate and other is bone dry.
The state will now be compelled to augment the capacity of existing storage structures in coastal regions, construct check dams and new reservoirs, and link rivers, wherever possible, as suggested by the report.
"Unless this is done, the future looks pretty bleak. With a majority of the rivers being interstate, dependence on neighbouring states should end," a member of the study team said. The good news is that the 41-year data shows there is no dramatic change in the trend in the onset of northeast monsoon.
