Why is there a rainstorm in Taiwan Province Province?

The definition of rainstorm, rainstorm, when there is continuous rainfall, and the accumulated daily rainfall reaches 130 mm, a "rainstorm special report" will be issued; If the rainfall is less than130mm, but more than 50mm, which may cause disasters, a "special report on rainstorm" will be issued. This disastrous rainy weather usually occurs in May and June of the rainy season; Or when the rainy season front in spring and autumn and the southerly airflow in summer are strong, there will be convective rainstorm or torrential rain. The attack of typhoon and the introduction of strong southwest airflow are also one of the reasons for heavy rain or torrential rain.

Rainstorm in Taiwan Province Province: The natural environment formed by the geographical location, climatic conditions and topography of Taiwan Province Province is full of rainstorms and floods, and the sediment deposition of the Yellow River forms the Taibei Basin, as well as the plain areas such as Yanglan, Taichung, Zhang Yun, Jianan, Kaohsiung and Pingtung. These endless fields, which are formed by abundant rain, are the land that aborigines depend on for hunting and living, and also the natural environment faced by the ancestors who crossed the sea to open up wasteland. Therefore, it can also be said that there would be no rich and prosperous Taiwan Province Province without storms and floods.

Although the rainstorm and flood have contributed to the civilization of Taiwan Province Province, when the rainstorm and flood occur, the rapids, choppy waters, landslides, and overflow may cause great loss of life and property.

According to statistics, during the 30 years from 1950s to 1980s, the average annual direct loss caused by floods in Taiwan Province Province reached 142 billion yuan (calculated in the currency of 1980s), accounting for about 0.68% of the gross national product. In order to prevent and avoid floods, and then store and use floods for the benefit of the people, we should study the rainstorm and floods in Taiwan Province Province, so as to plan appropriate and effective countermeasures.

As early as four years tomorrow (1624), before the Dutch occupied Taiwan Province Province, China people had moved to Taiwan Province Province, but until the return of Taiwan Province Province to the Qing Dynasty in the 22nd year of Kangxi (1683), there were few records about typhoons and heavy rains in the literature.

Although there is no modern hydrological instrument to measure the size of the rainstorm and flood in Qing Dynasty, the date and disaster situation of the rainstorm and flood can be found in various historical documents and memorials, and some of them also record the depth of the flood. If we only calculate the time when Taiwan Province Province belonged to the Qing Dynasty, that is, from the 22nd year of Qing Emperor Kangxi to the 21st year of Guangxu (1683- 1895), there were 220 windstorms on February13.

After the Japanese ruled Taiwan Province Province, modern meteorological and hydrological observation instruments were introduced, and meteorological observation stations, rainfall stations, water level stations and hydrological stations were set up. , and has a relatively reliable quantitative record. According to statistics, there were 178 typhoons hitting Taiwan Province Province in the 49 years from the first 15 years of the Republic of China to the 34 years of the Republic of China (1897- 1945), with an average of 3.7 times a year. According to the data, from the first year of the Republic of China to the thirty years, the frequency of floods was the highest, with an average of 2.2 times a year, which was roughly equivalent to the last year of the Qing Dynasty. In the 50 years of Japanese rule in Taiwan Province Province, there were only 8 years without floods.

After the recovery of Taiwan, it not only continued to carry out various observations, but also promoted the modernization of hydrological observation, widely set up rainfall stations and hydrological stations, purchased advanced hydrological instruments, and improved the quality of hydrological data. According to the statistics of the Meteorological Bureau, during the 57 years from 1934 to 1990, a total of 243 typhoons hit Taiwan Province Province, with an average of 4.26 typhoons per year. Among them, there were 8 typhoons in 1980 and 1990, 7 typhoons in 3 years and 6 typhoons in 3 years.

According to the statistics of the fire department, from 1947 to 1989, there were 1463.39 * * in Taiwan Province province. Another 37 floods were caused by rainstorm, such as the August 7th flood in 1948, with a total of 183 times, with an average of 4.25 times a year. The most frequent floods occurred in 1989, 8 times in 1979, 8 times in 1983 and 7 times in five years, all after 1970.

Typhoon and rainstorm cause disasters. Due to the increase of population and development and utilization area, the average number of floods caused by rainstorm is increasing every year. However, after 1970, ten construction projects were completed, the economy developed rapidly, the land was intensively used, and the land subsidence in the coastal plain became more and more serious, which may be related to the increase of the average number of floods per year, and also increased the disaster losses.

Cause of rainstorm: destroying forest will increase the amount of water flowing out of forest catchment when it rains, thus increasing the flood volume. However, basically, forests can only significantly reduce the amount of water in minor rainstorms, but cannot significantly reduce the amount of water in heavy rainstorms that will cause major disasters.

It is also considered that El Nino phenomenon and its appearance may cause meteorological anomalies and lead to concentrated heavy rain. El Nino current is a warm current from north to south along the coast of Peru in South America after Christmas. Generally speaking, it may lead to heavy rain in the tropical eastern Pacific with little rainfall, while the rainfall in the originally rainy tropical western Pacific may decrease or even appear drought. El Nino is a phenomenon in which the sea surface temperature in the eastern and central tropical Pacific Ocean is abnormally lowered and the trade winds become stronger.

The influence of global warming is the cause of heavy rain. It has been pointed out that due to global warming, the average amount of water vapor on the earth will increase, heavy rainfall and tropical depression will also increase, and the flow of rivers will increase by more than 7%.