Changing dynamics of monsoon

More lead time for forecasts is crucial for planning and strengthening capacity to respond effectively to disasters

By Author Dr Ramesh Chennamaneni   |   Published: 21st Aug 2019   12:05 am Updated: 20th Aug 2019   11:00 pm

With global warming, monsoon is changing, breaking well-established ‘rules’, and becoming more and more erratic and unpredictable. So the criteria of monsoon onset need to be refined accordingly. Climatological norms, which are a 30-year average of a weather variable, must be reconsidered in the context of climate change.

The Indian summer monsoon is likely to withdraw from the central part of India between October 14 and 24. This unique forecast, made for 70 days in advance, is the only available forecast for India from the Potsdam Institute for Climate Impact Research in Germany, which has proved successful for three years in a row.

Long-term Forecast
The monsoon withdrawal date is of crucial importance for the Indian people. In a warming world, severe storms and floods during monsoon retreat are becoming frequent. Such a long-term forecast could help the government do strategic planning, consolidate resources and strengthen capacity to respond effectively to disasters.

The end of the season is shifted due to very high temperature on the periphery of monsoon in Pakistan and Afghanistan. It takes longer time when the whole continent cools down to the temperature of monsoon withdrawal. The Potsdam Institute for Climate Impact Research (PIK) said, “we hope this alert in August will be taken into account at carrying out preventive measures in the system of dams in order to prevent its overfilling and floods in October.”

Crucial For Planning
Close to half of the global population depends on the monsoon rainfall. Floods in different States raise questions about the understanding of monsoon, preparedness to deal with rivers in spate to reduce the gap between climate research and its application in policy, business and societal decisions, particularly regarding agriculture, hydrology and water resources, and migration issues.

Prior knowledge of the date of monsoon onset is of vital importance in India. More lead time for monsoon forecasts is crucial for planning agriculture, water and energy resources management.

The southwest monsoon has left a trail of destruction this year. Nearly 500 people have reportedly lost their lives in Kerala, Karnataka, Maharashtra, Gujarat, Assam and Bihar. In Kerala, which experienced its worst deluge in a century last year, over 80 people have lost their lives in five days since August 8. In neighbouring Karnataka, the toll stands at over 48. Northern Karnataka, which was facing drought-like conditions in May, is now under water and the State is witnessing its worst floods in 45 years. In Maharashtra, more than 40 people have lost their lives in Sangli and Kolhapur districts, while the Marathwada and Vidharbha regions are reeling under a drought.

monsoon

Flood Fury
The floods this year have drawn attention to the changing dynamics of the southwest monsoon. Take the case of Kerala. According to the India Meteorological Department (IMD), the State recorded over 25% deficit in rainfall between June 1 and August 7. But Kerala has nearly made up the deficit in the past five days. Similarly, on August 8, Karnataka received nearly five times the rainfall the State receives in a day. Kodagu, the State’s worst flood-hit district, received 460% cent above normal rainfall between August 5 and 11.

In fact, monsoon rains in the past five years have followed a pattern: A few days of intense rainfall sandwiched between dry spells. But this behaviour of monsoon has changed all over the Indian subcontinent.

The focus this year, as in the past, has been on providing relief to the flood-affected. But questions must also be asked about the ways States prepare for, and deal with, floods. The vagaries of weather, for example, demand cooperation between States that share a river basin. This year, Maharashtra and Karnataka bickered over opening the gates of the Almatti dam on the river Krishna. By the time the two States agreed over the amount of water to be discharged from the dam’s reservoirs, the damage was already done.

The floods also drive home the urgency of focusing on nature’s mechanisms of resilience against extreme weather events. Policymakers and planners have shown little inclination to place wetlands, natural sponges that soak up the rainwater, at the centre of flood control projects.

Misplaced Priorities
Flood governance in the country has placed inordinate emphasis on embankments. But the floods in Bihar and Assam showed — for the umpteenth time — that these structures are no security against swollen rivers. Of course, what is true for the Western Ghats States may not hold for Assam and Bihar. But the message from the floods this year is clear: there is a need to revisit the understanding of the monsoon, particularly under changing climatic conditions, and find ways to deal with its fury.

According to the World Meteorological Organization, July’s global average temperature matched (and maybe broken) the record for the warmest-ever logged month – July 2016. Global heat in July was replaced by torrential rains in August in Asia and North part of Europe. Heavy rainfall has also triggered flooding in central and northern parts of India, Pakistan, Bangladesh and Nepal leaving tens of thousands displaced and millions affected.

The summer monsoon rainfall is the most important source of water in India. About 80% of the river flow occurs during the four to five months of this season. India collects and stores rainwater in the system of dams in the monsoon season to sustain itself in the dry season. In particular, hydroelectric power plants are driven by the water collected during the monsoon.

Taking into account very intensive rainfall in August, dams are supposed to be full in September. It is very important to alert the management of the dams that monsoon is unlikely to stop at the beginning of October in the central part of India.

Looking back to 2018, the severe cyclonic storm Titli appeared unexpectedly around October 11, and it was still rainy until October 18. In 2017, monsoon withdrew from the region around October 15. It is now well-established that the monsoon is changing with climate change. In view of this, a new approach must be evolved.

(The author is an MLA and Chairman, Indo-German Climate Change Project)

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