Cyclonic system may overlap with high tide to maximise damage if landfall happens late evening on May 26
The Sundarbans, spread over 20,000 square kilometres on either side of the India-Bangladesh border, are likely to be highly affected because of tropical cyclone Remal. The cyclone is set to make landfall late May 26 evening around Khepupara in Bangladesh’s Barisal division, according to India Meteorological Department (IMD) sources.
Khepupara is adjacent to the Bangladeshi section of the Sundarbans. It is around 100 km away from the Indian border.
The deep depression over the Bay of Bengal will turn into cyclonic storm Remal on May 25 evening. It is likely to cause significant damage to the Indian part of the Sundarbans as well. The Bangladesh Meteorological Department (BMD) also predicted a similar trend of the cyclone.
According to IMD, a major part of southern West Bengal (including Kolkata) will be impacted to varying degrees with heavy to very heavy rainfall as well as storm winds with speeds in the range of 62 to 91 kilometres per hour (kmph).
A scientist of IMD told Down To Earth (DTE) that the cyclone may make landfall late evening on May 26, rather than midnight as predicted officially so far.
Sundarbans experts point out that in case of a late evening landfall, the cyclone impact may overlap with high tide which will be set into motion by 7 pm and reach a peak around 11 pm on May 26. This could lead to storm surges and majorly damage embankments, affecting thousands of people.
“The administration is taking all steps as required. We will evacuate people from vulnerable areas as per protocol,” West Bengal’s Sundarbans Affairs minister Bankim Hazra told this reporter on May 25.
Moving away from Indian coast
The special bulletin released by IMD at noon on May 25, reads, “The deep depression over East Central Bay of Bengal (lies) about 440 km south-southeast of Khepupara (Bangladesh), about 440 km south-southeast of Sagar Islands (West Bengal) and 480 km south-southeast of Canning (West Bengal).”
The communique further stated: “It is very likely to continue to move nearly northwards and intensify into a Cyclonic Storm … around 25th May evening. Continuing to move further northwards, it would intensify into a Severe Cyclonic Storm by 26th May morning on northwest and adjoining northeast Bay of Bengal by 26th May morning and cross Bangladesh and adjoining West Bengal coasts between Sagar Island and Khepupara by 26th May midnight as a Severe Cyclonic Storm with wind speed of 110-120 gusting to 135 kmph.”
However, a senior scientist associated with the IMD cyclone division in Delhi has confirmed that the landfall is likely to happen close to Khepupura in Bangladesh as per the model analysis on May 25 morning.
“After turning into a cyclone, it will not have to traverse a long area, around 400 km, before landfall that may happen in late evening. Hence, the probability of becoming stronger gets diluted, and the cyclone will be in the ‘severe’ to ‘very severe’ category,” said the expert.
IMD has officially predicted on May 25 morning that the wind speed at landfall is expected to be “110-120 gusting to 135 kmph”. A cyclone is categorised as ‘very severe’ when it touches wind speeds of 120 km per hour.
Sundarbans on alert
Saiful Islam, a climate scientist and Intergovernmental Panel on Climate Change author from Bangladesh, told this reporter on May 25 morning that BMD has also predicted the landfall to be around Khepupara.
Islam, however, cautioned that the process is a dynamic one and it is difficult to pinpoint the exact location of landfall as of now.
“Sundarbans, across the border, is supposed to be highly affected by cyclone Remal, and one can say that multiple factors linked to climate change, particularly global warming and rising sea surface temperature, are contributing to the increasing trend of high intensity cyclones in the area,” said Islam.
IMD has predicted that “storm surge of about 1 metre above astronomical tide is likely to inundate low lying areas of coastal west Bengal around time of landfall”. According to the Kolkata Port Trust, the expected highest astronomical level during May 26 night high tide is about 5 metres. An addition of another 1 metre may cause overtopping and breaching of mud embankments in various places.
“The time of the landfall is very important. If it happens around midnight as predicted so far, then the impact of the embankments will be less, as the low tide will have begun. However, if the landfall happens late evening, it will add up with high tide as happened in the case of Cyclone Aila, and can cause extensive damage in the Indian Sundarbans particularly in Gosaba, Hingalguge and Sandeshkhali blocks,” noted Subhas Acharya, a member of the Sundarbans Development Board in West Bengal.
“Kolkata is likely to witness storm winds in the range of 60 to 90 km so far but that may come down. The city is expected to receive a lot of rain in between May 26 afternoon and May 27 afternoon, with very high rain for about 4-5 hours,” said an IMD Kolkata scientist.
“Kolkata may actually witness winds in the speed range of 40 to 50 kmph, almost like norwesters, as the system will make landfall about 150 km away from Kolkata,” stated another IMD expert.
A senior official of the state disaster management department shared that almost all south and central West Bengal districts have been alerted about cyclonic storm and rainfall. Other districts have been alerted over heavy rain.
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