Our country has fully entered the main flood season! This knowledge is worth keeping

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On July 1, China enters the peak flood season. How is the start date of this season determined? What is the critical period for flood control? How can one be informed in advance of flood disaster warnings? The answers are here ↓↓↓

What is the peak flood season? Analyzing based on the patterns of heavy rainfall, since 1998, 76% of the extreme heavy rainfall events in the southern region have occurred between June and August, while in the northern region, 78% of such events have taken place between July and August. Over the years, 61% of the strong typhoons that hit China between April and October, as well as 65% of the super typhoons, have occurred between June and August. From the perspective of flood occurrence patterns, since 1949, 91% of the regional floods in the major rivers of the south have occurred between June and August, and since 1998, 89% of the recorded floods have happened during this period. In the major rivers of the north, 86% of regional floods since 1949 have occurred between July and August, and since 1998, 72% of the recorded floods have taken place during this time. At 41 key monitoring stations along major rivers, the average start date of flood alerts in the southern rivers is May 26, while in the northern rivers it is June 27. Statistically, the peak flood season in southern provinces (river basins) usually begins around June 1, whereas in northern provinces (river basins) it starts around July 1. In most provinces (river basins), the peak flood season ends before August 31. Therefore, it is determined that the peak flood season in the southern part of China is from June to August, while in the northern part it is from July to August.

What is the critical period for flood control? The critical period for flood control refers to the “July to early August” period. Traditionally, this is understood to mean the last days of July to the first days of August. However, due to climate change, it is now generally interpreted as the second half of July to the first half of August. During this period, floods occur frequently across the country, making it the most challenging time for flood control each year. Historically, the devastating floods such as those along the Huai River in July 1975, the Yellow River in August 1982, and the Hai River in August 1996 and July 2023 all occurred during this time. In the Yellow River basin, 4 out of 5 regional floods since 1949 have taken place between mid-July and early August. In the Hai River basin, all 5 regional floods since 1939 have occurred during the same period. In the Liao River basin, 9 out of 11 regional floods since 1949 have occurred between late July and mid-August. In addition to the rivers in the north, major rivers in the south can also experience severe flooding. For example, in the Yangtze River basin, the highest water levels at key monitoring stations have occurred between mid-July and mid-August in 4 of the regional floods since 1949. In the Taihu Lake basin, the highest water levels in 6 out of 12 regional floods since 1949 have appeared during the same period. Therefore, the critical period for flood control is determined to be from July 16 to August 15