The annual phenomenon called monsoon, which is the lifeline for India’s agri-sector, arrives on the southern tip of Kerala in the first week of June and retreats from Rajasthan by September. Rain-dependent farm produce contributes about 14% of India’s economy but the sector employs more than half of India’s 1.3 billion population.
The weather forecaster Skymet has predicted below normal monsoon rains during June-September 2019 (summer monsoon), which is 93% of the long-term average. The culprit is warming of the eastern equatorial Pacific Ocean which is called El Niño phenomenon. This precipitation-deficient scenario is likely to have an impact on the availability of drinking water and rain-fed khariff crop output which is going to affect the living conditions of people in 80% of the country. The RBI has projected a rise to 3.9% by the end of December.
Overall, the amount of summer monsoon rainfall is influenced by a number of factors including El Niño, enhanced convection (increase in moisture in air due to high evaporation) over tropical west Pacific Ocean, Indian Ocean Dipole (IOD), etc. A strong El Niño induces changes in the atmospheric circulation over the tropical Indo-Pacific region leading to severe drought in many regions like Australia, Southeast Asia and India, while flooding other parts of the world such as the US Midwest and Brazil. The IOD is an ocean-atmosphere phenomenon in the Indian Ocean characterised by a difference in sea-surface temperatures between tropical eastern and western Indian Ocean.
In a research published in Pure and Applied Geophysics, researchers from Indian Institute of Tropical Meteorology, Pune, found that the summer monsoon during the past 22 El Niño years the Indian monsoon rainfall was mostly below normal over most parts of the country. However, the association between El Niño and deficient rainfall or drought was observed over the region west of longitude 80 E and north of 12 N (or 75% of India).
During the five strong El Niño years — 1877, 1899, 1911, 1918, and 1972— many areas of India suffered large rainfall deficiencies and severe droughts. There were four moderate El Niño years — 1887, 1914, 1953, and 1976 — when the suffering was marginal. The Indian Meteorological Department (IMD) had forecast a normal monsoon for 2018. However, the monsoon resulted in a 9.4% deficit in rainfall. Not just that, 2018 was also the fifth consecutive year to register a shortfall. Deficit monsoon has become chronic with 13 of the last 18 years witnessing below-normal rains. The period also saw 7 drought years — 2002, 2004, 2009, 2014, 2015, 2016 and 2017.
Rains replenish 67% of annual groundwater resource. The deficit rains are taking toll on groundwater levels in north India, thereby affecting crop productivity through reduced irrigation. The situation is a matter of concern in Punjab, Rajasthan, Haryana and Delhi, where the annual groundwater consumption is more than the annual groundwater recharge. Less rainfall and more pumping of groundwater for commercial activities lead to further drop in the groundwater table,
