Consecutive days of moderate rainfall helped fill up Pune dams last year: IMD
PUNE Even though the heavy rainfall events in Pune city have increased over the past few years, a recent study undertaken by scientists at India Meteorological Department (IMD) Pune has highlighted that consecutive days of moderate rainfall in the city and adjoining areas last year filled the three dams (Panshet, Varasgaon and Khadakwasla) solving the drinking water issue.
Monsoon kicked off a little late in July (2020) which prompted local authorities to think about cutting down the water supply and exploring the option of artificial rainfall.
The paper was presented by Anchal Khushwaha, junior scientist with the weather forecasting division of IMD, Pune at the annual monsoon workshop organised by Indian Meteorological Society, Pune on ‘Cloud precipitation process.’
Along with Khushwaha, Jyoti Sonar, a scientist in the weather forecasting division, was also a part of the paper “Extreme rainfall warnings in monsoon 2020- Steps to liasoning with disaster managers for Maharashtra state’.
The paper was guided by Anupam Kashyapi, head of the weather forecasting division, IMD, Pune.
Research at the weather forecasting division aims at various operational aspects to benefit various users.
Kashyapi said that the monsoon every year has a unique characteristic. “Consecutive moderate rainfall has an impact on low lying areas and allied aspects. Similarly, last year there was a query from local governing authorities about dam recharge. This was later resolved as the forecast given by IMD was realised,” said Kashyapi.
Khushwaha said that last year, during the latter part of June and early July, rainfall was not good enough.
“This created a little bit of panic among the local governing bodies like the Pune Municipal Corporation (PMC), Pimpri Chinchwad Municipal Corporation (PCMC)and Central Water Commission, Pune. However, a sequence of consecutive days of mostly moderate rain in isolated areas in and around Pune district from June to September 2020 helped the recharge of Panshet dam,” she said.
“We found that during June 3 to June 5, 2020, the mean rainfall for Pune district for three consecutive days was 36.99 millimetre per day which resulted in 23.33 per cent of dam recharge,” said Khushwaha.
The study also revealed that between July 23 to July 26, 2020, the mean rainfall for the Pune district for four consecutive days was 17.45 millimetre per day which resulted in 40.42 per cent of dam recharge. Also, from August 5 to August 8, 2020, the mean rainfall for four consecutive days was 20.06 millimetre per day which resulted in 70.75 per cent of dam recharge.
Kashyapi said, “A similar trend was observed between August 13 to August 17, 2020, where the mean rainfall for Pune district for five consecutive days was 15.34 millimetre per day which resulted in 100 per cent of dam recharge.”
“From September 9 to September 12, 2020, the mean rainfall for Pune district for the period of consecutive four days was 17.57 millimetre per day which maintained the 100 per cent of dam recharge till the end of the season. Because of this good rainfall, ultimately the dam recharge for Pune district was 100 per cent of its capacity,” said Kashyapi.
He added that though there was a panic among various stakeholders due to erratic rainfall, the dam was recharged 100 per cent due to light to moderate rain in and around Pune.
Last year, as per IMD, Maharashtra received normal rainfall (16 per cent more than normal) while Madhya Maharashtra received excess rainfall (29 per cent more than normal), as well as Pune district, also received excess rainfall (40 per cent more than normal).
Increased warnings for heavy rainfall events
Sonar has also worked on another paper which highlights that Madhya Maharashtra last year received 89 warnings for extreme rainfall events between June to September.
“My paper ‘Extreme rainfall warnings during Monsoon 2020 by IMD’, explores how many warnings were issued between June 2020 to September 2020 for extreme rainfall events,” she said.
“In Maharashtra, a total of 299 warnings were issued. In Madhya Maharashtra, which includes Pune, a total of 89 warnings were issued due to extreme rainfall events,” said Sonar.