‘Intense spells of rain harming Delhi's ecology’
An analysis carried out by the Centre for Science and Environment (CSE) last year showed that this trend of short, but intense rain spells is making usable water scarce in Delhi.
Up until the evening of August 20, Delhi stood at a 60% monthly rainfall deficit. On August 22, the city’s rainfall recordings showed a surplus of 11%, according to India Meteorological Department (IMD) data.
This leap was a result of intense rainfall the national capital received largely within a span of six hours on Saturday. Scientists and weather experts said that such short, intense spells may appear to be a positive indication, but they are not doing any good to the city’s ecology.
IMD recordings showed that as on Sunday afternoon, the Safdarjung weather station, which provides representative data for the city, recorded a monthly rainfall surplus of 11% and Lodi Road station recorded a surplus of 5%. The Palam observatory still stands at a deficit of 19%.
On Sunday, only the weather station at Ridge received “trace rainfall” – light rain that is not enough to be recorded.
While the rain recorded till Friday was 63.7mm, it rose to 211.2mm by August 22, as against the normal 190.2mm by this time of the month. With no rain on Sunday, the jump of 138.8mm was the highest single-day rainfall to be recorded in August over the last 14 years and the ninth highest since 1961, IMD records showed.
IMD records show that previously, Delhi received such a heavy 24-hour spell in this month on August 2, 2007, when the city got 166.6mm rainfall. The highest-ever single-day rainfall recorded during this month is on August 2, 1961 (184mm).
IMD’s forecast says that light rain is likely to continue in the city for the next few days, but from August 25, Delhi could see another dry spell.
Met officials also said that Delhi this year is likely to see a “near normal to surplus” monsoon season.
Met officials said that the majority of Saturday’s rain (138.8mm) was concentrated between a six-hour window of 2.30am and 8.30am.
“If you look at the actual number of rainy days in August this time, there have only been four. From August 9, north-west India entered into a break monsoon phase and even before that, the month had a slow start to rain. The interesting bit is that from Tuesday, there is another dry spell in the forecast. So, essentially, the surplus that Delhi has recorded this month is a result of a single day’s rainfall,” a senior IMD official said.
Experts said that such short, intense spells, which Delhi has been observing over the last decade, are not conducive for the city’s ecology.
An analysis carried out by the Centre for Science and Environment (CSE) last year showed that this trend of short, but intense rain spells is making usable water scarce in Delhi. The analysis showed that between August 13 and August 19, 2020, the city’s rainfall produced enough wastewater to meet nearly 13% of the daily water demand.
In this period, Delhi received nearly 118.4mm of rainfall —143% more than the average. Such a heavy spell can produce around 87,000 million litres of water, the analysis showed. Apart from usable water going to waste, episodes of urban flooding and flash floods are also increasing because of this trend.
Mahesh Palawat, vice-president (meteorology and climate change) at the Skymet Weather Services, said: “We can explain the scenario with a small example; if we are thirsty we will benefit from drinking water at regular intervals. What happens if someone forcefully pours it down your throat? Your body’s natural reaction will be to spit out the excess. That is what is happening with nature too. Because these rains are excess, in short durations, they are not helping the ground water recharge. Water is just flooding into the city and going down the drain.”
The Minto Bridge, which is an annual pain point for the Capital, was finally flooded on Saturday despite the authorities putting in place a new drainage mechanism there which had kept it dry during the rains over the past couple of months. Authorities barricaded the road below the bridge, where a man drowned last year.
“The whole concept of modern day city planning is to adapt to an area’s natural circumstances. If rains are getting more intense and if population is increasing, then the infrastructure and it’s management will also have to adapt to it. We need a dedicated monsoon plan for the city, which addresses all aspects of the city – drainage, traffic, manpower management etc.,” said Sewa Ram from School of Planning and Architecture