Why is it flooding in Central India?
Scientists have not linked the current spell with climate change, but central India has been recording a rising trend in extreme heavy rain events
An overflowing Narmada threw life out of gear in parts of Madhya Pradesh and Gujarat and water released from the Hirakud dam flooded several districts of Odisha on the weekend. At least 24 people were killed in flooding in MP and Odisha and thousands were displaced as heavy rainfall lashed other parts of India, causing reservoirs to overflow. Rainfall has been 25% more than normal in August, which India Meteorological Department (IMD) says is the highest for the month in 44 years. The previous highest in August was recorded in 1983, when rain was 23.8% more than the normal. Here’s a quick look at reasons for flooding in central India:
• Persistent very heavy to extremely heavy rainfall, measuring over 20 centimetres (cm), was recorded in two-three days between August 25 and 27 in Odisha and from August 27 to 30 over Madhya Pradesh (MP).
MP’s Chhindwara district’s 12 weather stations recorded between 20 and 41 cm of rainfall on August 28 to 29. Chaurai recorded 41 cm in a day. India Meteorological Department (IMD) authorities are still assessing the data to come to the conclusion whether this is the highest-ever precipitation recorded on a day.
Gujarat region continues to record very heavy rain.
• A well-marked low-pressure area had formed over the Bay of Bengal, which moved very slowly from August 24 to 31 up to western Rajasthan bringing extremely heavy rainfall in its path. “Our analysis shows extremely heavy spells over MP were recorded only during one day between August 28 and 29 that triggered flooding. There is no likelihood of another low-pressure area forming over the Bay of Bengal immediately,” said RK Jenamani, senior scientist, national weather forecasting centre (NWFC), IMD.
• Now, rain will gradually reduce over central India and will begin over the northern plains, according to scientists. “Extremely heavy rain in MP and other parts of central India is mainly because of the formation of strong low-pressure area over western MP and eastern Rajasthan. We are expecting rain to decrease gradually over central India but Gujarat may experience very heavy rains for one more day. Rains will increase over the northern plains, when the monsoon trough shifts northwards around Wednesday (September 2),” said Dr Mrutyunja Mohapatra, director-general, IMD.
• Such unusually heavy rains led to rivers flowing at extreme flood situations. It signifies that the highest flood level is breached. Stretches of Mahanadi, Wainganaga and Narmada rivers are still flowing in extreme flood situations. Eight dams in Odisha, Maharashtra, Karnataka, and MP are at 100% capacity and will have to release water to accommodate more rainfall.
• While the floods have disrupted lives in these states, the excess rainfall can improve soil moisture and help with a good crop during the upcoming rabi season. “There are different ways of harvesting water. But the most important source of water for agriculture is groundwater. The focus should be on local storage and recharge systems. We have to store rainwater and avoid its run-off,” said Himanshu Thakkar, coordinator, South Asia Network of Dams, Rivers and People.
• The country has recorded 26.3% excess rains in August –-- the highest in 44 years with 61.5% excess over central India, 36.7% excess over the southern peninsula, 19.1% deficient over east and the north-east and 1.9% excess over the north-west parts of the country.
Scientists have not linked the current spell with climate change, but central India has been recording a rising trend in extreme heavy rain events.
According to “Assessment of Climate Change over the Indian Region”, a report of the Union Ministry of Earth Sciences (MoES) released earlier this year, showed that from 1950 onwards there has been a significant rising trend in the frequency and intensity of extreme heavy rainfall events over central India, along with a decreasing trend in the moderate rain events.
A study published in the Nature journal in 2017 by Indian Institute of Tropical Meteorology (IITM) had concluded that there was a three-fold rise in extreme rainfall along the west coast and central India between 1950 and 2015.