Our approach towards water-use management must change... IMD predicts rain, but how that water is managed is a state subject
There would be more unusual behaviour of rainfall patterns and intense rain in less number of days due to climate change
NEW DELHI: A week after the southwest monsoon covered the entire country, some parts of India are still reeling under rain deficit. The India Meteorological Department (IMD) has predicted that the monsoon would be near normal at the end of the four-month season. In an interview, K.J. Ramesh, director general of meteorology at IMD, talks about what the scenario is likely to be during next two months and how the department plans to strengthen its forecasting skills in view of the newer challenges. Edited excerpts:
The overall rain deficit stands at 13%. Is the IMD confident about its prediction of a normal monsoon?
June ended with a huge deficit of 33%, but within a span of 10 days, from 1 July to 12 July, it came down to 14%. A lot of accumulated deficit was covered. Monsoon showed a phase of remarkable recovery. Then, there was a gap of 8-10 days. It is again in a very active phase and is likely to show equal intensity as seen during the first week of July. We would definitely see another 10 days of good rains. By July-end, the accumulated deficit would be single-digit. What could have been detrimental to the monsoon was El Niño and that threat has passed. It was oscillating between weak to neutral so far, but is now neutral. The Indian Ocean Dipole (IOD) is positive, which favours the monsoon. There should not be any problem. However, continuous rainfall may not happen.
Half the monsoon season has passed. How do you view the rainfall scenario so far?
Over 50% of the area in India is rain-fed and sowing depends on sufficient residual soil moisture. If we look at the distribution of soil moisture in the country, it is fairly high in areas where it has rained and it is suitable for sowing. Central India has the maximum soil moisture content at present. The last two weeks of accumulated acreage deficit figures released by the ministry of agriculture shows the deficit has come down to 7% as compared to last year. The acreage is increasing. Our focus is that sowing should be completed before the first week of August and that deficit comes down to zero. Uttar Pradesh and Bihar have received good rains in July. Further augmentation of soil moisture is expected. Chhattisgarh is a plateau region, so all water goes to rivers, except for its northern part. Improvement is required in Andhra Pradesh, Karnataka, Telangana, Jharkhand, and Odisha where sowing needs to pick up.
The country is facing a severe water crisis and deficient rains could worsen the situation.
The water crisis is not because of rainfall. The monsoon was not bad last year as far as reservoirs are concerned. In September, the levels in reservoirs were better than the previous year and even the 10-year average. How come all that water was over by February? There is something wrong with our water-use approach. Monsoon rainfall would come only in July next year. In between there is no mechanism for rainfall, so why was that stored water not used properly? Why is it not first reserved for drinking purpose, taking the baseline requirement of summer into consideration? Our water-use management needs to undergo a different approach. Reservoirs, local tanks, aquifers from where groundwater is extracted need to be filled. IMD predicts rain, but how that water is managed is a state subject.
How do you explain the stark variation in rainfall received within cities, districts and states? Bihar witnessed intense floods this season, while parts of it were facing deficits.
Rainfall leads to run-off. When the holding capacity (field capacity) of soil moisture reaches 100%, the water would start flowing out of soil, which is called run off. Now if it continues to increase because of heavy rain, it converts to local flooding. In Bihar, it was not just local rain, but the continuous rainfall in the hills of Nepal, Sikkim, and Bhutan. All that rainwater is coming downwards and that’s how north Bihar was flooded. In case of the Mumbai floods, it is not just rainfall, but the development regime pursued over the years. Rainfall needs a passage to drain out, but if natural drainage system is blocked because of certain development choices of the past, they will have to deal with the consequences.
Does IMD have any plan to strengthen its weather forecasting services for farmers amid the worst agrarian crisis?
The reservoir storage in-flow from rain can support irrigated wheat, rice, and sugarcane. There is no deficit on the west coast, so reservoirs will get filled up. We need to worry about the yield of rain-fed areas of pulses, oilseeds and cereals. Crops need at least 70mm of rain for sufficient soil moisture for sowing to take place. We are preparing a crop calendar, by observing when sowing actually happens for a particular crop in a district. Once we put a dynamic crop calendar in our advisory support system, we can tell which week up to the 13th week (normal crop cycle), the crop needs mandatory rainfall and whether it’s likely to happen or not. If there is forecast of a dry spell and soil moisture is not expected to last that long, then we can advocate supplementary irrigation locally. IMD evaluates the soil moisture daily and predicts the soil moisture for the next 10 days based on the rainfall forecast. This information is also sent out to farmers twice a week through 132 Agromet units for four major crops. This should take care of large dry spells for rain-fed crops.
How has changing climate variations influenced the rainfall scenario?
There would be more unusual behaviour of rainfall patterns and intense rain in fewer number of days. These circulation anomalies caused by climate variations can happen anywhere, anytime during the season. There were no such records in the past, but new records can get created. When extreme events take place, they have no preferred location. That is how places such as Barmer in Rajasthan are witnessing floods. New zones of extreme events are getting created and there are new kinds of extremes. All this is a manifestation of climate change.
How does IMD plan to strengthen its prediction capabilities in future amid these challenges?
Two years ago, we upgraded to high performance computing facility, which enabled us to run 3x3km models for three-day prediction and probabilistic prediction of rainfall in districts in different ranges, up to 5cm, 5-10cm in 12x12km grid scale (144sq. km). For 2024, we have sought funds from the government to enhance our computational capabilities, so that we could predict at a much finer scale of 5 x 5km. Till April, we could not predict lightning and thunderstorm, but now we can. We have also improved our prediction of tropical cyclones with the dynamic atmosphere-ocean coupled model, which proved extremely helpful in the prediction of Cyclone Fani. The next target is to do coupling for land surface and the atmosphere, which would make our forecasting capabilities better, not only for heavy rainfall, but also for forecasting thunderstorms, lightning, and hailstorms.