Border rivers disappear

Uthukotttai: The departed northeast monsoon has left rivulets on the Tamil Nadu-Andhra border dry. The Arni river that flows through Periyapalayam, draining into Pulicat, and the Kosathalaiyar that drains into the Ennore creek, are dry as their water catchment areas, mostly small pockets of reserve forests located close to the Tamil Nadu-Andhra Pradesh border, have not received their due annual rainfall, leaving several check dams and small reservoirs in Tiruvallur and Vellore districts low on water. The only respite is that the small streams from the hillocks located inside the reserve forests are providing some inflow into these reservoirs, mostly catering to local irrigation.

Small streams from the hillocks located in Varadapalyam, Nagalapuram, Satyavedu and Pichattur on the borders of Chittoor and Tiruvallur districts usually enable a good supply of water into Poondi and the nearby land to be irrigated in Tiruvallur district, but with the destruction of forests and vegetation, the local water resource from these regions has reduced drastically over the years, said a forester in Tiruvallur district.

Streams were narrowing due to human intrusion, said R. Sridhar, a member of the Chennai Trekking Club. The water level in all the reservoirs in Tiruvallur and small dams was low this season and the inflow into the water bodies was in deficit, said a municipal engineer. According to Regional Meteorological Department sources, Tiruvallur and its nearby areas recorded a deficit rainfall of 42 per cent, receiving only 34 cm of rainfall this season against the usual 52 cm.

Next: District borewells already overtapped for water

District borewells already overtapped for water

K Karthikeyan | DC

Chennai: Chennai Metro Water (CMWSSB) might do well to rework its summer contingency plan a bit. It would not be a bad idea to consult the geologists in the state water resource organisation (WRO) before it starts digging 25 large borewells at Cuddalore and Tiruvallur, from where it plans to tap over 40mld to mitigate the water crisis during the dog days.

GO Ms.No: 52 issued by TN government on March 2, 2012, and the most recent investigation done by the groundwater circle of the state WRO would explain why the contingency plan is ill conceived. As per the GO, both Minjur and Tamara­ipak­kam (Ellap­uram bloc­k), where CMW­SSB plans to dig wells­,­ we­r­e classifie­d as dark or overexploited blocks.

A block will be classified as overexploited if over 100 per cent of the groundwater available there is utilized. Six of the 14 blocks in Tiruvallur district have been classified as overexploited, excluding Gumm­idip­oon­di, which was classified as semi-critical under press­ur­e from the gover­nmen­t.

Even WRO has admitted that salt water-sea water interface moved from 3.5km in 1972 to 10km in 1999. The scenario is not enc­ouraging in CMW­SSB’s other target Neyveli either.

The artesian wells located within 40km radius around Neyveli fell below 150feet soon after Neyveli Lignite Corporation (NLC) opened the second mine. The wells in Seem­ushnam aquifer were exha­usted nearly 15 years back, a senior geologist pref­erring anonymity reve­aled adding that the wells ought to be dug near Kumbakonam in Cudd­alore-Thanjavur aquifer if they were to tap groundwater.

The farmers in Neyveli are sure to see their open and bore wells parched if metro taps the very little water available there. According to the average groundwater level status observed by WRO, grou­ndwater of Cudd­alore and Tiru­vallur fell from 2.31­meters (from the gro­und level) and 1.88­mete­­rs in December 2010 to 6.15meters and 3.24meters respectively in December 2013.

Next: Krishna water reaches chennai

Krishna water reaches chennai

Chennai: There is some ray of hope for water starved Ch­ennaiites. The much-aw­aited Krishna water h­as finally reached the sta­te. About 45cusecs of Kri­shna water released from Kandaleru in And­hra Pradesh reached the inter-state bor­der Oot­h­ukottai ear­ly Monday.

Accor­ding to senior WRO officials who wrote to their And­hra counterparts seeking 1,000cusecs said the inflow is expected to increase steadily and a quantitative analysis would be possible by the weekend. Andhra Prad­esh , which downed Ka­nd­aleru shutters early last week, released wat­er on Saturday.

Tamil Nadu received 1.825­tmcft till last month. As per the inter-state water sharing agreement, AP should release 8tmcft du­ring July-October per­iod and another 4tm­cft during January-April period. Though the canal at Ubb­al­amadagu in An­dhra was largely the reas­on for short supply, Tela­ngana stir also did its bit to dep­rive precious wa­ter to the city.

“Krishna water is definitely a saving grace. If And­hra releases at least 4tmcft it owes us during Jan­­u­ary-April period, su­m­mer could be succe­ss­fully seen through with­out acute water sho­rt­age,” said a city water m­a­n­­ager.

The four city reservo­irs, Chem-baramb­akk­a­m, Poondi, Puzhal and Ch­­o­­lava­ram jointly store 3.144­tmcft, against the full capac­ity of 11.05­7tmcft. The curr­ent storage will roughly last up to three months.