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There was one consolation you could derive from the celebration of the World Meteorological Day (WMD) at the Regional Meteorological Centre, Chennai, March 23. The specialists pointed out – with facts and figures – that there had been many dry years for Chennai and Tamil Nadu. Would you believe that Chennai, which had an average 1,266.9 mm rainfall for the previous millennium, had received only 552.2 mm of rain in 1904, and 635.3 mm in 1938?

But there were also great deluges like in 1943 when it received 2,134.8 mm of rain, and in 1946, 2,085 mm and in 1996 it was 2,444.8 mm!

Though the experts had comforting words saying there was no overall change in the rainfall pattern or abnormal loss of forest cover, there was this nagging doubt: deficit rainfall in the earlier years was all right because the ‘users’ were also fewer in numbers. With the capital growing and spreading out, the need for water has risen sharply. But that is another story.

The WMD is celebrated to commemorate the formation of the World Meteorological Organisation (WMO) March 23, 1950.

This year’s theme was ‘Weather, Climate and Water in the Information Age.’

As part of the WMD celebrations, the Regional Meteorological Centre, Chennai, had organised for talks by various eminent speakers like Dr A Mohanakrishnan, chairman, Cauvery Technical Cell, Chennai, and T N Balasubramanian, professor and head, Department of Agricultural Meteorology, Tamil Nadu Agricultural University, Coimbatore.

S Sridharan, chairman, Indian Meteorological Society (IMS), said in his welcome address meteorology had developed in the latter half of the 19th century and said future advancements would include technologically advanced instruments like weather radars, which play a vital role in tracking cyclones.

Dr Mohanakrishnan, speaking on ‘Weather, Climate and Water in the Information Age’, said overall, rainfall has remained stable and there was no serious threat to the forests.

Mohanakrishnan, explaining the significance of water, said there were hundreds and thousands of tanks scattered all over Tamil Nadu and Andhra Pradesh and they were being used for storage. Apart from this, Tamil Nadu has built 50 small reservoirs in the last three years, he said.

To a question about the total storage area in Tamil Nadu, Mohanakrishnan said it stood at 180 tmc ft.

Prof Balasubramanian, speaking on ‘Monsoon and water crisis in Tamil Nadu’ said “Monsoon plays a vital role in agriculture and Tamil Nadu depends on the two monsoons, South-West and North-East.”

Giving statics of the two monsoons, the professor said the South-West Monsoon gives 32 per cent rainfall, the North-East gives 48 per cent, 15 per cent of rains are summer rains and the balance 5 per cent is unseasonal rains.

Out of the 30 districts in Tamil Nadu, Dharmapuri, Salem, Kanyakumari and Villupuram are dependent upon the South-West Monsoon, and other districts benefit majorly from the North-East Monsoon.

Explaining the demand for water in Tamil Nadu, he pointed out that 40 per cent to 50 per cent, i.e., 26 lakh hectares out of 1,30,069 km2 of the total geographic area, is irrigated and the average annual rainfall for the state is 946 mm. Agriculture requires 85 per cent of the total available water. The supply-demand gap in the year 2025 will be two million hectare metre (MHM).

Balasubramanian urged farmers to adopt water-saving techniques and not to plant crops that require more water. Citing World Bank statistics, he said the industry and power sectors use 13 per cent of water, the community uses 4 per cent of water and irrigation, 83 per cent.

The north-eastern part of Tamil Nadu receives more rain than other parts of the state. Groundwater is exploited more, he added.

S R Ramanan, director, Regional Cyclone Warning Centre, Chennai, speaking on ‘Review of Performance of South-West Monsoon 2003’, said in 2002, the South-West Monsoon was deficient by minus 49 per cent. 

Y E A Raj, deputy director general, Regional Meteorological Centre, Chennai, who spoke on ‘Global Features Associated with the South-West and North-East Monsoon 2003’, said if the southern oscillation was positive, it would lead to a good South-West Monsoon but bad North-East Monsoon and vice versa.

In 2003, the South-West Monsoon was good for India. The rainfall deficiency for the years 1996-98 was better than 1999-2003, which was was sub-normal.

V K Raman, director, Meenambakkam Regional Meteorological Centre, gave vital statistics in his speech on ‘Salient Features of Chennai City Rainfall’. From 1901-2003 the annual rainfall for Chennai had been 1,266.9 mm. In 1996, Chennai received 2,444.8 mm of rain; in 1943, 2,134.9 mm; in 1946, 2,085 mm; in 1997, 2,085.8 mm; and in 1930, it was 1,998.7 mm.

Speaking about low rainfall in Chennai through the years, he said in 1904, the metro received only 552.2 mm of rain, in 1938, 635.3 mm; and in 2003, 738.1 mm. In 1926, Chennaivasis got only 797.6 mm rain and in 1927, 823.5 mm.

Meteorologist P V Revikumar who reviewed the performance of the North-West Monsoon, said for 12 districts had received less rains and the deficieny level for Chennai was minus 54 per cent.

M Jarraud, secretary-general, World Meteorological Organisation, in his message distributed during the celebration, said “For this day, the theme 'Weather, Climate and Water in the Information Age' is selected in recognition of the vital role of technology in advancing meteorological, hydrological and related geophysical sciences that enable the National Meteorological and Hydrological Services (NMHS) to contribute to the socio-economic development and to the protection of the environment. WMO, therefore relies on, and actively promotes, the application of such technologies to the monitoring, understanding and prediction of the behaviour of the atmospheric and oceanographic systems and the water cycle.”