What are the main hazards caused by storm surge disasters?

(A) the main characteristics of storm surge

Storm surge refers to the abnormal rise of sea level caused by strong atmospheric disturbance such as tropical cyclone (typhoon, hurricane) and temperate cyclone (cold current). The sea level fluctuation recorded by coastal tide gauge or estuary water level station is usually a comprehensive feature of sea level change caused by long-wave vibration such as astronomical tide, storm surge and tsunami. The general tide gauge has filtered out the sea surface fluctuation caused by short-period waves for a few seconds. If the storm surge coincides with the astronomical climax (especially during the astronomical tide), the storm surge is often accompanied by violent wind and waves, which will often make the tides in the coastal areas affected by it soar, and even the tides will destroy and devour the seawalls.

Some people call storm surge "storm tsunami" or "meteorological tsunami". In China historical documents, it is often called "sea overflow", "transgression", "tsunami" and "tidal wave", and storm surge disaster is called "tidal disaster". The spatial range of storm surge is generally from tens of kilometers to thousands of kilometers, and the time scale or period is about 1-65438+.

According to the characteristics of atmospheric disturbances that induce storm surges, scholars at home and abroad divide storm surges into two categories: typhoon storm surges caused by tropical cyclones (or tropical storm surges, which are called hurricane storm surges in North America and tropical cyclone storm surges along the Indian Ocean coast) and temperate storm surges caused by temperate weather systems such as temperate cyclones. China is one of the few countries in the world where both kinds of storm surges are very serious, and storm surges may occur all year round. All the coasts from south to north are not spared. Storm surge is usually named after the weather system that causes storm surge at home and abroad. For example, the storm surge caused by typhoon 1980 (internationally known as typhoon Joe) is called typhoon storm surge 8007 or storm surge Joe; 1969 The storm surge caused by Hurricane Camille, which landed in North America, is called the Camille storm surge.

Whether the storm surge can cause disasters depends largely on whether its maximum storm tide level overlaps with the astronomical high tide level, especially with the astronomical high tide level. Of course, it also depends on the geographical location, coastal morphology, coastal and seabed topography of the affected areas, especially the socio-economic (disaster-bearing body) situation in the coastal areas. If the maximum storm tide level coincides with the astronomical high tide level, it will lead to catastrophic tidal disasters. For example, typhoon storm surges No.8923 and No.92 1 6+0992, from August 28th to September1day, were affected by the strong tropical storm No.0/6 and astronomical tides. Storm surge disasters have occurred in the eastern coast of China since 1949. The flood disaster has spread to Fujian, Zhejiang, Shanghai, Jiangsu, Shandong, Tianjin, Hebei, Liaoning and other provinces and cities. The combined action of storm surge, huge waves, strong winds and heavy rain has hit the coastline of nearly 10,000 kilometers from Dongshan Island in Fujian in the south to the coast of Liaoning Province in the north. 193 people died, seawall 1 170 km was damaged, farmland was affected19.33 million hectares, 333,000 hectares were damaged, and the direct economic loss was more than 9 billion yuan.

Of course, if the storm surge level is very high, even if there is no astronomical tide or high tide, it will cause serious tidal disasters. This is the case with the storm surge of typhoon 8007. At that time, it coincided with the flat tide in the astronomical tide, and the extremely high storm surge water level of 5.94 meters still caused serious storm surge disasters. According to the opinions of storm surge experts at home and abroad, storm surge disasters are generally divided into four grades. Namely, catastrophic tidal disasters, severe tidal disasters, relatively large tidal disasters and mild tidal disasters. The storm surge disasters in China discussed in this section include the extraordinary tidal disasters and some serious tidal disasters along the coast of China from 1949 to 1995.

(2) Storm surge disaster

Storm surge disaster ranks first in marine disasters, and most of the major coastal disasters caused by strong storms in the world are caused by storm surge. On June 5438+0970+065438+1October 13, a tropical cyclone storm surge disaster shocked the world. A storm surge more than 6 meters high claimed 300,000 lives and drowned 50 livestock. More than 1000000 people are homeless. Despite warnings of tropical cyclones and storm surges, another severe storm surge in April still claimed130,000 lives. On September 26th, 2009, the surrounding area of Nagoya on the top of Ise Bay in Japan suffered Japanese history. The highest tidal level reaches 5.8 1 m. At that time, the water level along the coast of Ise Bay soared, and the storm surge provoked thousands of waves to rush to the embankment. The tidal seawall was washed away in a short time, causing 5 180 deaths, more than 70,000 casualties, and the affected population was 65.438+0.5 million. The direct economic loss (current price) was 85.2 billion yen, including hurricane (typhoon) storm surge and temperate gale storm surge. 1969 Hurricane -Camille, which landed on the Gulf Coast of the United States, triggered a storm surge of 7.5 meters, which is the first storm surge record in the world so far. Historically, the Netherlands has been flooded by seawater more than once, and it has reclaimed land from the sea more than once. These lands protected by tidal dikes account for about all the land in the Netherlands.

In the history of China, the loss of life and property caused by storm surge is shocking. 1782 In Qing Dynasty, a strong temperate storm surge affected seven counties from Wudi to wei county. 1On April 28th and 29th, 985, a storm surge occurred in Bohai Bay, which destroyed almost all the buildings in Dagukou and turned the whole area into a "Zeguo". More than 2,000 people died in the Haiphong camp. On August 2nd, 1922 strong typhoon storm surge hit Shantou, causing huge storm surge disaster. According to historical records and textual research by Zhu Kezhen, a famous meteorologist in China, more than 70,000 people were killed and more people were homeless. This is the storm surge disaster with the largest death toll in China since this century. According to Chaozhou Chronicle, the typhoon "shakes mountains and shakes mountains". Heavy rain poured down, the water depth of the flat land was more than ten feet, and the coastal area was less than ten feet, and many villages were involved in the waves. ""especially the victims, such as the sand outside Chenghai, the whole village lost their lives and property. "This county has a village with a population of more than 65,438+100,000. More than 7,000 people died in this storm surge disaster. The local government turned a blind eye to this, which led to the epidemic raging and more than 2,000 deaths. Typhoon wind force exceeds 12. There have been many very serious storm surges in Shanghai in history. The most serious one occurred in 1696. " On the first day of June in the thirty-fifth year of Kangxi, the wind and rain were like a note, the time was too dry, and the ditches flooded in an instant, cheering. Two hours later, the tsunami broke out suddenly, the hurricane resumed, and the tide took the wind and momentum. Jiading, Chongming, Wusong, Chuansha, Zhelin Eighth and Ninth Regiments, etc. , has lost thousands of feet, 18000 kitchen households, more than 100000 people drowned. Night suddenly fell, people stopped caring for each other, and there was no way to escape until the morning water receded and the bodies piled up like mountains. This is the deadliest storm surge disaster in China since it was recorded in writing.

According to statistics, during the year 2000 from Han Dynasty to A.D. 1946, there were 576 catastrophic tidal disasters along the coast of China, and the number of people killed in a tidal disaster ranged from several million to tens of thousands to hundreds of thousands.

In the 40 years since the founding of the People's Republic of China, China has been hit by storm surges many times, which has also caused huge economic losses and casualties. 1956 12 (Wanda) caused a severe storm surge, which flooded 400,000 mu of farmland in Zhejiang Province and killed 4,629 people. No. 1969 No.3 (Vio). It caused a serious storm surge disaster in Shantou area. Shantou city was flooded, the streets were flooded1.5-2m, and the Niu Tianyang levee was washed away. With the efforts of the local government and army, there are still 1554 deaths. However, compared with the storm surge 1922 with the same intensity in the same area, the death toll decreased by 98% .5438+April 5, 096. Seawater flooded into the land for 20 to 30 kilometers, causing the most serious storm surge disaster along the Bohai Sea since 1949. The Yellow River Estuary was pushed by tides, flooded, and the disaster situation intensified, causing heavy losses to people's lives and property in Laizhou Bay and the Yellow River Estuary. On another occasion,1April 23, 969, the temperate storm surge in the same area caused seawater to invade the coastal areas from Wudi to Changyi and Laizhou. During the 45 years from 1949 to 1993, there were 269 typhoon storm surges with the maximum water increase exceeding 1 m in the * * process in China, of which 49 storm surges exceeded 2m and 10 exceeded 3m. * * * caused 14 catastrophic tidal disasters. A total of 547 temperate storm surges occurred along the Bohai Sea and the Yellow Sea coast in China, with the maximum water increase exceeding 1m, of which 57 were over 2 m and 3 were over 3 m, resulting in 4 severe tidal disasters, 6 major flood disasters and 6 1 time of mild tidal disasters.

In the past 40 years, despite the rapid increase of coastal population, the number of people who died from tidal disasters has obviously decreased, which cannot but be attributed to the superiority of China's social system and the success of storm surge forecasting and early warning. However, with the development of industry and agriculture in coastal areas and the increase of coastal infrastructure, the disaster-bearing bodies are getting bigger and bigger, and the direct and indirect losses of each storm surge are getting bigger and bigger. According to statistics, the average annual economic loss of storm surge in China has increased from about 654.38 billion yuan in the 1950s to about 1000 billion yuan now. It has increased to about 2 billion yuan per year at the end of 1980s and 7.6 billion yuan per year at the beginning of 1990s, reaching 93.2 billion yuan and 654.38+0992 and 654.38+0994 respectively. Storm surge is becoming the main restricting factor of coastal opening and social and economic development.