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EXPLAINED: How Monsoon Got Held Up, Why Many Parts Are Yet To Get Normal Rainfall

The start-stop monsoons this year have already resulted in a decline in the sown area over last year, a worrisome sign amid a jump in inflation. The government’s weather officials have now said that rain clouds have now covered the entire country after a pause, but vast areas of the country are still staring at deficient rainfall, which may spell trouble for agriculture.

How Far Has Monsoon Advanced?

The Indian Meteorological Department (IMD) had said that the southwest monsoon had travelled up the country till about the middle of last month following its slightly delayed onset over Kerala on June 3 as it was borne on by a “favourable atmospheric circulation and a low pressure system over Bay of Bengal”.

By June 13, IMD said, the monsoon had “covered most parts of the country except northwest India”. However, a trough in mid-latitude westerly winds led to a weakening of easterly winds over northwest India, which then caused a hiccup in the advance of monsoon into remaining parts of northwest India.

On July 13, the IMD said in a weather bulletin that the southwest monsoon had further advanced into the remaining parts of the country, including Delhi and the areas in UP, Punjab, Haryana and Rajasthan that had till then been untouched by monsoon rains. The weather office, hence, concluded that the southwest monsoon had “covered the entire country on July 13 against the normal date of July 8, adding that the persistence of “moist easterly winds from the Bay of Bengal in the lower levels… resulted in enhanced cloud cover and scattered to fairly widespread rainfall”.

What Had Caused The Delay?

IMD had noted on July 12 that post June 20, there were “weak/break monsoon conditions” across the country that had affected the further advance of rain clouds across the country. Noting the reasons for delay, it said that one factor was the lag in the formation of low pressure area over Bay of Bengal while the absence of a monsoon trough at mean sea level near Delhi also played a part. It added that the monsoon was also held up as “5-6 western disturbances moved west to east across North India, which dominated over the monsoon easterlies”.

But from July 9 onwards, “easterly winds were established over planes of Northwest India”, leading to an increase in cloudiness and relative humidity.

What Is The Status Of The Rainfall Now?

According to state-wise data for distribution of rainfall across the various districts between June 1 and July 19, about 58 per cent of a total of 693 districts for which data was available had received at least normal rainfall while 287 districts (42 per cent) had seen deficient rainfall.

Of these, 84 districts — the bulk of them lying in the three states of Telangana, Tamil Nadu and Karnataka — had received “large excess” rainfall. On the other hand, 247 districts, with Madhya Pradesh, UP, Gujarat, Odisha and Rajasthan accounting for more than half of them, had received deficient rainfall.

According to IMD, when rainfall is ≥60 per cent of long period average (LPA), it is termed “large excess” while excess rainfall is said to have occurred when it ranges between 20-59 per cent of the LPA. Shortfall of between 99-60 per cent is categorised as “large deficient”. Lag in rainfall of between 59-20 per cent is termed deficient rainfall. Normal rainfall ranges between -19 per cent to +19 per cent of the LPA.

The forecast for this year for the country as a whole was that rainfall would be 101 per cent of the LPA. The LPA for estimating southwest monsoon is based on the average rainfall over the period between 1961-2010, which is 88cm.

IMD says that “when the rainfall averaged over the country as a whole is within… 90 per cent to 110 per cent of LPA, the rainfall is said to be ‘normal’ while rainfall is said to be ‘below normal’ when it is less than 90 per cent of LPA. Rainfall more than 110 per cent of LPA is classified as ‘above normal’.

How Has The Monsoon Affected Cropping Patterns This Year?

Earlier this month, news agency Reuters said that total sowing area this year had clocked a decline of more than 10 per cent over last year due to the slowing down of the monsoon. Indian farmers have planted 49.9 million hectares with summer crops so far in 2021, it said, adding that the data was provisional and could be revised as the season continues.

The main summer crop, rice, had been sown over 11.5 million hectares till July 9 as against 12.6 million hectares in the previous year although the cropping area for sugarcane was unchanged over 2020 at 5.3 million hectares.

About half of all agricultural land in India is dependent on the monsoon, which itself accounts for 70-90 per cent of yearly rainfall. Reports say that the poor rainfall so far can negatively impact India’s economic recovery amid the Covid-19 induced recession. Agriculture represents about 15-18 per cent of India’s over $2 trillion economy. An adverse consequence of inadequate or delayed rainfall will be the rate of inflation, which in June breached the Reserve Bank of India’s upper ceiling of 6 per cent.

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Source: News18