Geographical characteristics of the Bay of Bengal

Its deep-sea basin is roughly U-shaped with a depth of 4500m. The basin floor has two characteristics: the east is a straight ridge of 90 degrees east longitude, which is 5,000 kilometers long, and the Ganges Delta is alluvial by shelf sediments. The crest of the ridge at 90 degrees east longitude is about 21.34m deep, and its northern end is covered with sediments from the Ganges Delta. There are dendritic ditches (fan valleys) in the delta.

Because of its topographic effect, various forces are concentrated in circumferential annular flow, so tidal range, static vibration and internal waves are obvious. Its coastal trade is developed, and its main ports are Kolkata, Madras, Bangui, Chittagong, Yangon, Mahlman, Phuket, Thailand, Penang, Banda Aceh, Indonesia, Jaffna and Sri Lanka. The Bay of Bengal is the birthplace of tropical storms. It is generally believed that most of these storms occur in the tropical waters of 5 -25 degrees north and south latitude. Typhoon, produced in the western Pacific Ocean, often attacks the Philippines, China, Japanese and other countries; Hurricanes originate in the Atlantic Ocean and often attack the United States, Mexico and other countries. They are called hurricanes. Every year from April to June 10, that is, at the turn of summer and autumn, violent storms are often accompanied by tidal waves, which set off huge waves and roared to the mouth of the Ganges-Brahmaputra River, causing great disasters. 1 970165438+1October 12, a strong storm formed in the Bay of Bengal hit Bangladesh, killing 300,000 people and leaving more than110,000 homeless. On September 20th19th and 20th, 2005, heavy rains hit southern India, causing floods in the coastal state of Andhra Pradesh, leaving nearly 654.38+million people homeless and causing a large number of casualties among local residents. Due to heavy rain, two major rivers have no dikes, resulting in the flooding of railway tracks and main roads leading to the city, at least 23 trains connecting northern and southern India have been cancelled, and another 12 train has been diverted to other routes. In Andhra Pradesh, 100 towns and 1300 villages were cut off, thousands of trees and telephone poles were uprooted by strong winds, and railways, highways and traffic were seriously blocked. According to local media reports, most of the dead died of electric shock or house collapse. The airport runway in the port city of Visaka Putnam is still closed due to accumulated water.

More than 35,000 residents living in low-lying areas have been evacuated to temporary shelters in government buildings and schools. Reuters quoted the office of Bangladesh Disaster Response Center as saying that the gale caused by tropical depression in the Bay of Bengal caused huge waves as high as 1.3 meters along the coast of Bangladesh, causing 1.2 million people to flee their homes. The official of the office said: "Some rivers have burst their banks, and the soaring river has washed away the bridge. In addition, at least 65,438+0,000 families have moved from the worst-hit Noakali area to the highlands. " According to local meteorological officials, at least 40 fishing boats were missing when the storm landed on the southern coast last weekend, with about 300 fishermen on board. An official of the Ministry of Fisheries said: "This fishing fleet used the fishing season to enter the Bay of Bengal, apparently ignoring the warning of bad weather." The Coast Guard and fishermen's organizations then launched a search and rescue operation in Dubo Acali, a disaster-stricken city in the south. Officials of the Ministry of Fisheries said that these missing fishermen may still have hope of survival, because according to past experience, "some missing fishermen can return safely after the storm". Bangladeshi government officials have not commented on this news. However, the local meteorological department said that storms and tornadoes formed in the Bay of Bengal in September and1October each year will hit the eastern coasts of Bangladesh and India. Just in time for the full moon, the gravity of the moon and a series of small earthquakes made the flood more fierce.