PUNE: Water conservation and planning is the need of the hour. Although it sounds cliché, the truth is according to the study by India Meteorological Department (IMD), 30 per cent of country’s area was under drought condition, whenever all India southwest monsoon rainfall was –15 per cent or less than the normal.
While talking to Sakal Times, Dr Pulak Guhathakurta, Scientist F, Head, Climate Data Management and Services, said, “Meteorological drought during the southwest monsoon season and for the northeast monsoon season over five meteorological subdivisions of India for the period of 1901 to 2015 has been examined using district and all India standardised precipitation index (SPI).” The study is titled – ‘Trends and variability of meteorological drought over the districts of India using standardised precipitation index and the authors were P Guhathakurta, Preetha Menon, PM Inkane, Usha Krishnan and ST Sable in December 2017.
“Whenever all India southwest monsoon rainfall was less than −10 per cent or below normal, for those years all India SPI was found as −1 or less. Composite analysis of SPI for the below normal years, viz., less than −15 per cent and −20 per cent of normal rainfall years indicate that during those years more than 30 per cent of country’s area was under drought condition, whenever all India southwest monsoon rainfall was –15 per cent or less than normal,” Dr Guhathakurta added.
“During 115 years’ period, there were 24 years when rainfall departure was less than –10 per cent and thus were below normal years. During the period 1901–2015, there were four years, viz., 1965, 1972, 2002 and 2009, when SPI was in the extremely dry category and out of that 1972 was the most,” he said.
Trend analysis of monthly SPI for the monsoon months identified the districts experiencing a significant increase in drought occurrences. Significant positive correlation has been found with the meteorological drought over most of the districts of central, northern and peninsular India, while negative correlation was seen over the districts of eastern India.
“For the first time, meteorological drought analysis was done over districts and its association with equatorial Pacific Sea Surface Temperature (SST). Temporal correlation of all India southwest monsoon SPI and south peninsular India northeast monsoon SPI has been done with the global SST to identify the teleconnection of drought in India with global parameters,” Dr Guhathakurta added.
It has been observed that the variability of monsoon droughts over India is significantly influenced by the tropical sea surface temperature anomalies.
The regions in western and southwestern parts of the country, viz., east and west Rajasthan, west Madhya Pradesh, Saurashtra and Kutch, Konkan and Goa, Madhya Maharashtra, coastal and south interior Karnataka and also in eastern sides, viz., coastal Andhra Pradesh, and Gangetic West Bengal have no districts showing decrease in SPI or increase in drought occurrences.
A DECREASE IN SPI VALUES SEEN IN DISTRICTS
Districts of central India and extreme south peninsular India during the months of June, July and September, while in August it was over eastern, north-eastern and Tamil Nadu region. In east MP, Bihar, Jharkhand, east UP, Punjab, Uttarakhand, Kerala and northeast states during July and August. While more number of districts show a significant decreasing trend in August than July, but for the state of Kerala, the decreasing trends are not significant.