By Dr R. H. Patil, Department of Agricultural Meteorology, UAS, Dharwad
This year, as per the India Meteorological Division (IMD), New Delhi forecast given on 14th May the onset of southwest monsoon over Kerala was likely to be on 31st May with a model error of ± 4 days and Kharif season (Jun-Sep) is going to be normal in the state which is a positive thing during the hard times of COVID-19 pandemic.
The rainfall anomalies also suggested that North Interior Karnataka (NIK) region is likely to witness above-normal rainfall during the four months of Kharif. Kharif is the most critical period for farmers of India during which almost 75% of annual total rainfall is received and helps boost food grain production.
It is equally important for the farmers of north Karnataka as most commercial and cash crops like cotton, chilli, maize, green gram, soybean, groundnut, and paddy that help farmers gain economically are grown in large areas during Kharif.
While excess rain marred the last two Kharif seasons (2019 and 2020) across most parts of NIK leading to widespread flooding and crop losses, the farmers of this region want the least during this season is another excess rainfall or drought. They badly need a normal monsoon spread uniformly over four months to harvest bumper crops. However, predicting the ever-dynamic behaviour of weather is an easier said than done task.
The latest progress of monsoon and conditions in ocean water and wind movement suggests that monsoon is likely to hit Kerala coast either on-time i.e., May 31s or June 1 or even a day or two early, but what is a little concern is the strength of the monsoon.
Impact of cyclones on the onset and strength of the monsoon
Because of the rapid heating of ocean waters until the end of April, especially in the Arabian Sea and Bay of Bengal, we witnessed two depressions turning into extremely severe cycles and left a trail of destruction in their path.
Tauktae cyclone which was formed in the Arabian sea during the second week of May went along the coast some 200-250 km in ocean waters next to Karnataka but delivered heavy rains in the coastal region, much needed moderate to heavy rains in the Western Ghats, Malnad region and moderate rain at most places across plains of North Interior Karnataka (NIK). This helped farmers at most places to prepare farmlands. However, Tauktae cyclone left a trail of destruction in Coastal Maharashtra and Gujarat. Lots of lives were lost, and it damaged the property on its path despite advance tracking of the cyclone path and the best efforts of the Government and NDRF teams.
Similarly, a week later, the second depression of the season originated in the Bay of Bengal and soon turned into a severe cyclone named Yaas and hit Odisha and West Bengal again, leading to loss of life and property.
Both Tauktae and Yaas cyclones, as per IMD MC, Bengaluru experts, carried lots of moisture from the ocean waters raining in their path of movement leading to cooling of ocean surface water temperature than normal for the period, and also cooled most of the landmass of the southern peninsular region during the peak month of summer.
The lower than normal ocean surface water temperature (SST) and weaker winds may not delay the monsoon on time, but strength will be reduced, which means, as per IMD experts, the first two weeks of monsoon may bring less rainfall than normal rains and later monsoon may pick up its strength.
IMD also says the monsoon may cover the whole of Karnataka between June 5 and 10, but due to the effect of two back-to-back cyclones and the latest conditions, there is also a chance that the monsoon may effectively cover Karnataka later than forecasted.
Likely scenarios in case of the weak onset of Monsoon:
The weak onset of the monsoon may lead to a couple of scenarios for the NIK region: either the whole of NIK region including coastal and Malnad may receive less than expected rain during the first two weeks, or it may bring normal rain to Coastal, Western Ghat and Malnad region, but rest of NIK including plains may remain dry or sub-optimal for sowing during first two weeks.
This will throw a spanner in the plan of things of farmers from the NIK region, especially in the Malnad region and adjoining districts like Belagavi, Dharwad, Haveri and Gadag, where this summer excess pre-monsoon rains have been received. In fact, between 1st March and 29, May five districts received excess rainfall between + 75 to +316 % compared to the long period average for the period. Another four districts received above-normal rainfall ranging between +35 to +40% over a long period average for the same period.
Most farmers from these districts have prepared their land and either taking up sowing, especially paddy and maize in the Malnad region, or buying seeds like green gram, soybean, maize and onion and getting ready to take up sowing with soaking rain. In the above scenarios, sowing would be delayed, but in any case, we may have to wait and watch the progress and strength of monsoon for another few days before drawing any definite conclusion before planning definitive Agro-advisories and measures.
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