Assam may receive a fourth of its annual rainfall in the next 10 days. Around 500-600 millimetres of rainfall is expected in the Brahmaputra valley till June 19, 2022, according to weather forecasting website Windy.
Monsoon system forecast for the next 10 days on the website showed that from June 12-June 20, 2023, that is, in just eight days, Assam will exceed the normal rainfall for June by 490 to 415 mm.
Read more: Here is what Assam can do to prevent floods
According to the central government’s weather forecast agency India Meteorological Department (IMD), there is a possibility of heavy rainfall in the Assam and Meghalaya subdivision till June 12, 2021. However, the IMD has only recommended keeping an eye on the situation.
The subdivision received a total of 858.1 mm of rainfall in June 2022, according to the IMD. This was the highest downpour for the month in 121 years and had caused a huge loss of life and property in the region.
In June 2022, Assam alone received 669 mm of rainfall, 61 per cent more than the usual 415.2 mm, according to state-wise data from IMD. Meghalaya faced 1,493 mm rainfall, 107 per cent more than the average of 722.1 mm.
The state gets 2,818 mm of rainfall in a year on average. The monsoon usually reaches Assam in the first week of June. The system of monsoon winds is active and is moving towards the state at the moment, according to Windy.
Through June 17-18, a fourth of the annual rainfall — that is, about 600-700 mm may occur in Assam. Though this situation will likely be less than the record rainfall of last year, it can also bring life-threatening floods in the Brahmaputra valley.
All the rivers of Assam are responsible for floods as they receive heavy rainfall in a short period, according to a report based on 30 years of climate data by IMD (1989-2018). Water from the neighbouring Himalayas also reaches Assam very fast.
The rivers swell in a very short time and start breaking the banks. They contain a large amount of silt and debris, which quickly reach the river and increase the water levels.
The state has seen several devasting floods over the last few years. Other than in 2022, floods occurred in 2019 and 2020 as well. However, despite all the information available, disaster control authorities remain unprepared. Last year’s floods from June 14 to 29 killed 124 people, the IMD said on the basis of media reports.
Significant weather events in India in June 2022. Source: IMD
Kokrajhar district receives the highest rainfall in June and July in Assam, showed the 30 years’ IMD data. The district receives 757 mm of rainfall in June, 714 mm in July and 561 mm in August, while Chirang district receives the most rainfall in September (456 mm). The least amount of rainfall occurs in Karbi district.
Dhemaji, Dibrugarh, Jorhat, Naigon, Lakhimpur, Darrang, Golaghat, Majuli and Kamrup districts get flood affected in the state, according to the Assam State Disaster Management Authority.
In June, Chachar, Hailakandi, Lakhimpur and Dhemaji districts in Assam get 17.2 to 19 days of rainfall on average, showed IMD data.
Meanwhile, Karbi Anglong, Hojai, West Karbi Anglong, Dima Hasao, Nagaon and Golaghat districts receive rainfall for 11-13.2 days in June. The number of rainy days in other districts range to 17.2 from 13 in June.
The southwest monsoon rainfall is highest in Assam in July (28.7 per cent) and then in June (28.6 per cent), the 30 years’ data further showed. About 66 per cent of the annual rainfall is in the southwest monsoon (June-September).
The average normal rainfall in the month of June is between 415 to 490 mm. June 2018 saw 351.9 mm rainfall in Assam. June 2019 recorded 323.1 mm (deficit rainfall), 526.2 mm (large excess) in June 2020, 381.4 (normal) in June 2021 and 669.6 mm (large excess) in June 2022.