Storm surge triggered by Yaas and spring tide inflict heavy damage in Bengal
The storm surge triggered by Cyclone Yaas, which coincided with the perigean spring tide of Wednesday’s full moon, inflicted heavy damage in the coastal and deltaic areas of West Bengal, chief minister Mamata Banerjee said on Wednesday as she monitored the situation from a control room set up the state secretariat.
The state government has evacuated around 1.5 million people to cyclone and relief shelters. More people were being evacuated till reports last came in as sea and river water gushed into the low-lying areas, flooding villages.
“Because of the cyclone and the spring tide, the storm surge has caused extensive damage in the state. Several embankments have been breached. Water has gushed into many places at Digha, Shankharpur, Sagar, and Gosaba. Low lying areas have been flooded,” said Banerjee.
Storm surge is the abnormal rise in seawater level during a cyclone and can lead to flooding in low-lying areas.
Around 70km of embankment has been damaged in the coastal district of East Midnapore district, which shares a border with Odisha. In South 24 Parganas, reports of embankment breaches have been reported from at least 15 places.
At least 20,000 houses have been already damaged, according to early estimates provided by the state government.
Banerjee urged the people, who were lodged in the cyclone and relief shelters, not to return to their houses as the spring tide phase would continue till Thursday.
According to estimates given by the Kolkata Port Trust, the water levels would reach their peak around Thursday morning.
The India Meteorological Department (IMD) warned on Tuesday that the storm surge, triggered by Cyclone Yaas and the perigean spring tide, could reach up to 4 metres over and above the astronomical tide (spring tide).
“The maximum damage would be caused by the storm surge this time. On May 26, when the cyclone hits, there is also the spring tide. The damage would be the maximum in the coastal districts of East Midnapore and South 24 Parganas,” Sanjib Banerjee, deputy director-general of IMD’s regional office in Kolkata, said on Tuesday.
Experts said the water level in the sea rises at least a metre high during a spring tide, which occurs during a full moon, over a normal high tide that comes every day. The water level is highest during the perigean spring tide when the moon is closest to the earth.
“The storm surge triggered by the cyclone at East Midnapore district would be 2m–4m, while in South 24 Parganas it would be 1m–2m. This is over and above the astronomical tide (spring tide),” said Banerjee.
For storm surge, the IMD had issued a red warning, the highest level of warning that calls for taking action, for the East Midnapore district. For South 24 Parganas district an orange warning (officials to remain prepared) had been issued.