Delayed onset, withdrawal of monsoon: Time for farming in India to adjust?

A few weeks back, the India Meteorological Department (IMD) said that the southwest monsoon is expected to begin its withdrawal from parts of Rajasthan from the first week of September.

However, later it updated the forecast saying that in view of the changed weather conditions that include a build-up of the fresh weather systems in the Bay of Bengal, the withdrawal could be delayed.

If the monsoon withdrawal is again delayed this year, this would mean that for the second straight year, the southwest monsoon isn’t leaving the country on time.

This is also in tune with the analysis done by IMD a few years back, where it had reworked the monsoon arrival and withdrawal dates over central, west and north India, except for southern parts of the country.

Also Read: Deficient rainfall likely to hit kharif production in Uttar Pradesh

If the onset and withdrawal of monsoon get delayed frequently then it could have a profound impact on the sowing pattern of kharif crops and also many other things directly associated with the monsoons.

A delayed withdrawal of monsoon might help in leaving good soil moisture for the preceding rabi crops, but it could make the standing kharif crops prone to damage and pest due to prolonged exposure to rains at the pre-harvesting stage.

So when does IMD consider monsoon as having been withdrawn from the country?

According to the IMD, withdrawal of southwest monsoon starts from extreme north-western parts of the country is not attempted before 1st September.

Thereafter, after 1 September, the following major synoptic features are considered for the first withdrawal from the western parts of northwest India.

These are cessation of rainfall activity over the area for continuous five days, the establishment of anticyclones in the lower troposphere and considerable reduction in moisture content as inferred from satellite water vapour imageries and tephigrams.

Thereafter, further withdrawal from the country is declared, keeping the spatial continuity, reduction in moisture as seen in the water vapour images and prevalence of dry weather for five days.

In total, the withdrawal of the southwest monsoon is from the southern peninsula and hence from the entire country only after 1st October, when the circulation pattern indicates a change over from the southwesterly wind regime.

Change in onset and withdrawal dates

In April 2015, in a move that could have some impact on agriculture, water and power management in parts of the country, the IMD revised the monsoon onset and withdrawal dates over parts of North-West, Central and West India delaying it by 3-7 days in some case and advancing it by few days in some other cases.

However, the annual rains will continue to hit the Kerala coast around June 1, while leaving the country around October 15.

The withdrawal dates over much of central and north-west India, where a substantial part of the farming activities are dependent on rains, were now expected to be 7-14 days later than their usual time.

The met department revised its monsoon onset and withdrawal dates over parts of India based on its extensive analysis of recent data.

For changing the onset dates it studied data from 1961-2019 and for revising the withdrawal dates it studied data from 1971-2019.

Till now, the monsoon’s onset and withdrawal dates were fixed using data from 140 monitoring stations from period of 1901-1940.

As a result, the southwest monsoon was now expected to hit Mumbai on June 11 instead of June 10, a delay of one day, but leave the city around October 8 instead of September 29, a delay of almost 9 days.

In Bhopal, the rains were henceforth expected to hit the city around June 22 as against the current onset date of June 15 but start withdrawing from 30 September instead of the current withdrawal date of September 20, a delay of 10 days.

In Lucknow, the monsoon was now expected to come around June 23 instead of June 22 but leave around October 3 instead of September 30.

In Delhi, the monsoon would arrive henceforth around June 27 instead of 23 but leave around September 25 instead of 22.

Overall, the IMD said that in states like Maharashtra, Gujarat, Madhya Pradesh, Chhattisgarh, Telangana, Andhra Pradesh, Odisha, Jharkhand, Bihar and parts of Uttar Pradesh, the monsoon will be delayed by 3-7days compared to the existing normal dates.

However, over extreme northwest India, the monsoon will arrive a little earlier, on July 8, as compared to the existing date of 15th July.

The total quantum of monsoon rains that India receives in the four-month season has also come down as the Long Period Average (LPA) for the June to September months has now been revised at 87 centimetres based on data collected between 1971-2020.

Earlier the LPA was 88.1 centimetres based on data collected between 1961 to 2010.

New and Old Monsoon Onset and Withdrawal Dates Over Some Major Cities

	Onset		Withdrawal
Cities	New Date	Old Date	New Date	Old Date
Mumbai	6/11/2022	6/10/2022	10/8/2022	9/29/2022
Bhopal	6/22/2022	6/15/2022	9/30/2022	9/20/2022
Lucknow	6/23/2022	6/20/2022	10/3/2022	9/30/2022
Delhi	6/27/2022	6/23/2022	9/25/2022	9/22/2022
Chandigarh	6/26/2022	7/1/2022	9/22/2022	9/22/2022

Source: IMD

Impact

Experts said the last two rabi and kharif seasons and their growing uncertainty have played a big role in lowering India’s wheat and rice production consecutively in a year.

Going forward these uncertainties will only get worse. Crops and seed varieties have to be developed that can withstand long days of monsoon stress or excess rains.

Also, fertilizer application, management of urban infrastructure and pesticide usage has to be tuned to cater to more acute and severe pest attacks.

The whole farming system in short has to be geared up to face such long-term changes in the climatological conditions in the country.