Monsoon variables

Spread of rain is more important than total precipitation

If the long-range monsoon prediction of the India Meteorological Department (IMD) holds true, the country can hope to get good rain during the four-month rainy season (June to September) for a fifth year in a row. Such prolonged phases of normal monsoon are quite infrequent, even if not unprecedented. The IMD anticipates the total seasonal rainfall to be 96 per cent of the long-period average. Though this prediction does not tally with the projection of below-normal rainfall (94 per cent) announced a day earlier by private weather forecaster Skymet, the difference is only marginal, which, for all practical purposes, is insignificant. What matters is not the total precipitation but its spread over time and space. Even deficient rainfall, if evenly distributed, can prove more rewarding than an ill-distributed normal or above-normal rainfall. Actually, only a fraction of the total rainwater is utilised for agriculture and other purposes, or is conserved in the surface and underground water aquifers. The bulk of it flows down wastefully to the seas, eroding the precious soil in its wake.

For the economy, a normal monsoon is vital for several reasons. Nearly 52 per cent of the country’s farmland relies wholly on rainfall for crop production, and agricultural income is a key determinant of rural demand for industrial goods and services. Robust growth in agriculture is imperative also to rein in food inflation, which had remained elevated for some time. It ruled at 5.95 per cent in February this year before softening to 4.79 per cent in March. Food prices account for over 40 per cent of the consumer price index. That apart, monsoon rainfall, which comprises over 70 per cent of the country’s annual precipitation, is critical for refilling the reservoirs to meet the lean-season requirement of water for irrigation and hydropower production.

This year, the IMD’s monsoon forecast was awaited rather eagerly because of the apprehension of the emergence of the El Nino (the warming up of the waters of the equatorial Pacific Ocean), which generally, albeit not always, mars the monsoon’s performance. The indication from the IMD, fortunately, is that this phenomenon would not begin to materialise before almost half the monsoon season is over. More importantly, there are a couple of redeeming factors as well, which might counter-balance the El Nino’s ill effects. These are the Indian Ocean Dipole (IOD) — temperature variations in the opposite poles of the Indian Ocean — and the relatively meagre snow stock in the northern hemisphere and Eurasia, which is believed to have a positive bearing on the monsoon system.

However, this is only the preliminary reckoning of the likely performance of the forthcoming monsoon. A better, and more reliable, picture would emerge from the updated forecasts to be issued by the IMD in May and June. Besides, there is no indication yet of the likely timing of the onset of the monsoon, which is critical for farmers to make their cropping plans and arrange for seeds and other inputs accordingly. This information, too, would be provided by the IMD in its subsequent weather bulletins. But the Central and state agriculture departments need to keep contingency plans ready to cope with any situation that might arise due to unforeseeable aberrations in weather, which are becoming too frequent due to climate change.