North-east monsoon, likely to set in around October 20, may follow suit
CHENNAI: This year’s south-west monsoon (June-September) may have been the worst for the country since 1972 with an overall deficiency of 23 per cent, but its adverse effect was less severe in Tamil Nadu.
During the four-month-period, the State recorded 313 mm rainfall against the normal 316 mm, a deviation of minus one per cent, according to the Meteorological Department. [The State Agriculture Department, in its policy notes for 2008-2009 and 2009-2010, regarded nearly 333 mm as the normal rainfall for the monsoon.
Going by the meteorological standards, the State witnessed a normal monsoon this time, as the value of deviation fell within the range of minus 19 per cent to plus 19 per cent.
The neighbouring Union Territory of Puducherry experienced a deficient monsoon with a deviation of minus 45 per cent. It received 180 mm rainfall against the normal 327 mm.
Of the 31 districts in the State, only four – Coimbatore, Salem, Theni and Tirunelveli – recorded excess rainfall. While rainfall in 14 districts was deficient, it was normal in the remaining 13 districts, according to the website of Regional Meteorological Centre, Chennai. [If the deviation is in the range of minus 20 per cent to minus 59 per cent, it is deficient. For excess, the deviation should be plus 20 per cent and more].
Apart from Chennai, Thanjavur, Nagapattinam and Tiruvarur, the three districts forming part of the Cauvery delta, were among the districts with deficient rainfall. Tiruchi and Madurai were among those with normal rainfall. Both Kanyakumari, which receives the benefits of two monsoons, south-west and north-east, and the Nilgiris experienced normal rainfall.
To say that the monsoon was bountiful in Coimbatore was an understatement. The district recorded 765 mm against the normal of about 193 mm, a deviation of 297 per cent. Salem registered 461 mm (normal: 380 mm); Theni – 271 mm (178 mm) and Tirunelveli – 130 mm (93 mm), the figures of deviation being 21 per cent, 52 per cent and 40 per cent respectively.
As for the Cauvery water realisation, this year’s south-west monsoon turned out to be reasonably good though it gave tense moments in its early phase. As of now, Tamil Nadu has realised 137.21 thousand million cubic feet (tmcft) of Cauvery water (against 137.97 tmcft stipulated by the Cauvery Water Disputes Tribunal in its interim order for the period since June 1).
This was because south interior Karnataka [where the catchment of Cauvery is located] recorded an excess rainfall of 27 per cent. Officials of the Water Resources Department say for the last three days, the Mettur dam received almost one tmcft a day and this trend should continue as the Cauvery delta did not receive much rain.
On the drinking water supply front, the Tamil Nadu Water Supply and Drainage (TWAD) Board, whose jurisdiction covers all parts of the State except Chennai, has started taking steps to maintain the supply level in areas where water sources are drying up. It has already created new sources in about 6,300 rural habitations, of which water supply is being given in 2,000 habitations.
Work on establishing infrastructure to provide supply in the remaining habitations will be completed by November-end. In about a dozen cities and towns, the Board has carried out combined water supply schemes ahead of the scheduled deadline, providing relief to people, says a senior TWAD Board official.
An official of the Meteorological Department says the north-east monsoon, which accounts for about 50 per cent of the State’s annual rainfall, is likely to set in around October 20, the usual date of onset. It is also expected to be normal.