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Assessment of Recent Droughts in Tamil Nadu

Tamil Nadu, a coastal state in south India, is prone to droughts. The climate of the state ranges from dry subhumid to semiarid. The state has three distinct rainfall climates: (1) advancing monsoon period (from June to September), with strong southwest winds; (2) northeast monsoon (from October to December), with dominant northeast winds; and (3) dry season (from January to May). The normal annual rainfall of the state is about 945 mm. Tamil Nadu is classified into seven agroclimatic zones: northeast, northwest, west, southern, high rainfall, high altitude hilly, and Cauvery Delta (the most fertile agricultural zone). The Cauvery Delta zone, located in the humid tropics, has a mean annual rainfall of 1,273 mm, with more than 60% of that coming from the northeast monsoon. An analysis of summer monsoon rainfall (June–September) for 1871–1991 shows that the state experienced below-normal rainfall in 30% of these years. During the summer, the average rainfall is 266 mm, but water demand is 663 mm. Hence it is a deficit season. The northeast monsoon brings an average of 529 mm rainfall and demand is relatively low—361 mm. Table 1 gives the climatic moisture status of different stations in Tamil Nadu in winter (I) and summer (II). It clearly shows that water deficit is more common in summer. This gap can only be bridged by irrigation. However, during the winter monsoon (northeast monsoon), soil moisture is recharged. Hence, the cropping system is centered on the northeast monsoon period. Drought is more recurrent during June–September. Its severity and extent during this season is believed to be more dependent on rainfall aberrations, ground water level, reservoir level, crop conditions, and soil type. The state has predominantly red, black, and alluvial soil types. Sandy soil regions of southeast Tamil Nadu suffer from chronic droughts. Tamil Nadu farmers, with a long history of experiences with natural disasters like droughts, have adjusted to the phenomenon through trial and error. Occasionally they have adopted sericulture, as is being done in the agroclimatic west zone of the state. However, modern agriculture requires effective cropping patterns suited to the rainfall distribution or probability of drought recurrence. Hence, assessment of past droughts (both qualitative and quantitative) and their impacts on the socioeconomic status of the state are necessary and may help policy makers and others in determining new courses of action. An assessment of droughts in Tamil Nadu from 1977 to 1991 reveals recurrent drinking water shortages in major parts of the state—the city of Madras in particular. The worst drought years in the past 15 years are id ntified as 1980, 1982, 1983, 1987, and 1989. The 1987 drought, which has crippled the state’s economy, is assessed and discussed here. Table 2 gives an account of expenditures on drought management and drought combined with flood. In 1983–84, the state incurred expenditures of 106.2 Crores because both floods and droughts were severe. The drought of 1980 destroyed the groundnut crop over one lakh (100,000) hectares in the districts of Chingleput and North Arcot. As a result of the failure of the northeast monsoon in 1980, drought prevailed in 3–4 districts in early 1981, resulting in the destruction of mangoes and coconuts. The 1982 drought caused huge losses in paddy and groundnut crops as well as drinking water shortages. Even the moisture-surplus regions of the state, like the Nilgiri hills, suffered from severe drought, resulting in the destruction of more than 6,000 hectares of tea plantation. The state also lost more than one lakh hectares of paddy, millets, and pulses during the 1983 drought. Hydropower generation failed because of very low water in the Mettur reservoir. The drought of 1987 put the entire state (as well as the country) in the doldrums. About 6,000 villages, 3 lakh hectares of crops, and 108 lakh cattle were affected. The 1987 drought serves as a model chronic drought year in Tamil Nadu, and it is interesting to study its redeeming features and its management. The catchment areas did not receive any water, and there were 290 poor rainy days, 48 marginal rainy days, and 27 good rainy days. The ground water level fell steeply, up to 11 meters. This was partly due to overexploitation of ground water and partly to a lack of legislation to curb this activity until the 1987 drought, when the state government passed the Madras Metropolitan Area Ground Water (Regulations) Act. The hardest hit crops were paddy, millets, and pulses. Out of 24 lakh hectares, paddy could be sown on only 20 lakh hectares, resulting in a yield of 56 lakh tons compared to a target of 66 lakh tons. Similarly, production of millets was only 16 lakh tons (compared to a target of 20 lakhs) and pulse production was 4.27 lakh tons (compared to a target of 4.75 lakh). As a part of contingency crop planning, seeds, fertilizers, and pesticides worth Rs. 45 lakhs were distributed to 2 lakh farmers (both small and marginal). Because of poor storage in the reservoirs, the cropping pattern was changed. A unique plan of “direct sowing” was advocated in particular to the farmers of Cauvery Delta of the Tanjur district. The strategy was to raise a rainfed crop, and when the reservoir level in the Mettur dam improved, the water would be released to supplement the rainfall. A large number of farmers had to be convinced to K. K. Nathan Water Technology Centre, Indian Agril. Research Inst. New Delhi, India