Three far correlation factors resulting in three large floods along the Yangtze River in the 20th century are analyzed as follws: (1) sunspot activity, (2) EL Nino event, (3) drastic earthquake in the south of the Tibet Plateau According to the basic facts between the large flood along the Yangtze River and the far correlation factor, the statistical law of the large flood along the Yangtze River is discussed It is pointed out that when the arising times of three factors reduplicate, the large flood will probably arise along the Yangtze River, which is of important indication function for the over long-term forecast of the large flood along the Yangtze River

The relationship between the peak stage and peak discharge is influenced by many factors in the flood system. Therefore, different peak discharges may occur under the same peak stage, while the same peak discharge may also occur under the different peak stages. If the peak stage set with similar peak discharges is taken as the fuzzy subset in the stage universe, then the membership function of these fuzzy subsets can be hypothesized to manifest a normal distribution graph. According to a k and b k , the mid-value of the universe element of the peak stage can be substituted into the normal distribution graph, and the fuzzy relational matrix can be obtained. Thus, the peak discharge can be calculated according to the peak stage using the fuzzy deduction theory. The relationship between the peak stage and peak discharge as Q = f(H) has an important impact on the determination of the peak discharge during the high-water level period in the flood forecast. In this paper, the fuzzy information analysis method is used to forecast the peak discharge, with the result in accordance with the actual event. This method can be seen as a new and effective method of flood prediction and forecasting.

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Three large floods along the Yangtze River in the 20th century

The Practical Application of Fuzzy Information Analysis in Flood Forecasting

In 1954, the Yangtze River valley was hit by heavy precipitation anomalies, which caused large casualties and economic losses; however, systematic analyses of the causes are lacking. Adopting the latest national historical precipitation data collected by the China Meteorological Administration (CMA) and global sea surface temperature (SST) records, this retrospective study determined the spatial–temporal distribution characteristics of the precipitation in 1954 in Wuhan, a city situated in the Yangtze River valley. The results confirmed that the 1954 precipitation anomalies were characterized by a high volume and a long period of rainfall, plus numerous cloudbursts, with most of the precipitation concentrated during June and July at the mid- and low-Yangtze areas along the Yangtze. An El Niño event caused the West Pacific subtropical highs to continually move southward during the summer, creating a long-term rainband in the drainage basin. Moreover, the continued low SSTs in the Sea of Okhotsk generated an active blocking high that continuously brought high-latitude cold air into the south, boosting precipitation over the drainage basin. This study proposed a new causal model of summertime precipitation across the Yangtze River valley in 1954, whereby the unusual SST changes initially triggered atmospheric circulation anomalies, which caused the precipitation anomalies of 1954.

/pdf/characteristics-and-cause-analysis-of-the-1954-yangtze-17x2y09y.pdf

Three large floods along the Yangtze River in the 20th century

Citations

The Practical Application of Fuzzy Information Analysis in Flood Forecasting

Characteristics and Cause Analysis of the 1954 Yangtze Precipitation Anomalies

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