PUNE: Long dry spells or wet spells are not only worrying the government, but it has become a dinner table worry at each and every household across the country. Although, there are various opinions by scientists over climate change and its impact, the changes in monsoon pattern are vivid and clear.
“There have been changes in the monsoon pattern in Maharashtra and India for sure. At the same time there has been an observation that the amount of rainfall in August has seen an increase across Maharashtra while it is decreasing in July,” said Dr Pulak Guhathakurta, Scientist F, Head, Climate Data Management and Services.
While talking to Sakal Times, Dr Guhathakurta said, “The pre-monsoon and winter rainfall in the State is decreasing. The rains which took place because of combative heating in the months of March and April too have decreased. Similarly, the overall monsoon has increased in Madhya Maharashtra while in Vidarbha it has decreased in Wardha, Bhandara, Latur and Osmanabad.”
In a research paper titled, ‘Detecting changes in rainfall pattern and seasonality index vis-`a-vis increasing water scarcity in Maharashtra’ by him and Elizabeth Saji, they studied the long rainfall data series (1901–2006) of districts of Maharashtra in monthly and seasonal scales and then mean rainfall and coefficient of variability are analysed to get the spatial pattern and variability.
“Geographical location of Maharashtra is such that it can be broadly divided into four meteorological subdivisions by India Meteorological Department. It includes sub-division Konkan and Goa which is to the extreme west, elongated north-south along the west coast of India.
“Due to this topographical feature, the region receives very high rainfall during monsoon season. The Vidarbha region is to the extreme east of the State. The mean monsoon or annual rainfall of this region is less than that of Konkan and Goa but more than the other two sub-divisions. The other two subdivisions, viz., Madhya Maharashtra and Marathwada have almost similar rainfall pattern although Madhya Maharashtra has a slightly higher mean monsoon or annual rainfall,” he explained.
Not a single district of Maharashtra reported increasing trends in rainfall from January to May (except Latur). In spite of increasing trends in monsoon rainfall in many areas, the decreasing trends in the first five months resulted in an increase in heating and may have an effect in the shortage of soil moisture, groundwater and lowering the groundwater level. Out of the 12 months, August has proved to be very good for Maharashtra as most of the districts have shown increasing trend in August rainfall. The other good month is October.
“The epochal decadal activity has shown that from 1901 to 1950 there was a dry spell and after 1951, it was a wet spell. So, from 1951 to 1971 we had a wet spell which did not notice any major changes in the rainfall pattern,” Dr Guhathakurta said. In the paper ‘Observed changes in southwest monsoon rainfall over India during 1901-2011’, the authors P Guhathakurta, M Rajeevan, DR Sikka and Ajit Tyagi analysed the southwest monsoon over India as a whole from 1901 to 2011 of 640 political districts of India.
He added, “However from 1971 till now there has been a decrease in some parts as the dry spell has been stretched over to nearly five decades now. The epochal activity means dry-wet-dry-wet spell cycle. Now, we are expecting that after 2021 the wet spell might begin. Meanwhile, the frequency of extreme events of floods or droughts over various regions in the country has been increased and this is because of climate change factor. The number of dry days is increasing and the rainfall from light to moderate, too, has seen a decreasing trend,” he said.