There was a downpour in the northeast of Hebei Province, the west of Liaoning Province, and in Xiliaohe River Basin of the Inner Mongolia on the 24th-26th, July, 1962. At the downpour centre, Renjiayingzi station on Xiliaohe River valley, the rainfall was 305.1mm on 25th, July, there was an extraordinary flood historically in Xiliaohe River valley. Because the Hongshan reservoir in the Laoha River was located in the upstream of Xiliaohe River, it was at the beginning of the reservoir's opration so that the empty status greatly decreased the damage that the flood might bring in the downstream of Xiliaohe River valley. In 1962, the number of incoming flood peak was 12700m³/s, the flood flow of six days was 12,780,000,000m³, more than the designed value once in a million years.
Rainfalls process
Affected by typhoons, it was raining heavily in the downstream of Luan River and the area alone Bo Sea on 24th July. The rainfall in the south region of Luan River was 374.0 mm,the rainfall in Bogezhuang served as 288.2 mm. The rainfall in Lengkou came as 302.8 mm on 25th, the rainstorm moved northwestward. The three days' rainfall in Shangzhangzi, Lingyuan County on the upper reaches of Daling River totaled 401.4 mm, as for the maximum measurement result, the average moisture in Chaoyang station on Dalin River whose catchment area was more than 10256 square kilometers served as 248.5 mm. Renjiayingzi on the upper reaches of Laoha River had a total rainfall in three days of 305.1 mm more than what it had been ever.
This storm affected many palces, such as Xiliao River, Li River, Dalin River, Yongding, Daqing in Hai River Basin as well as the plain in front of Yazihe. Rain belt ran from southwest toward northeast and the gross area that had a rainfall amount more than 100 mm covered 200 thousand square kilometers. The rainfall center was in Shimianzi on the lower reach of Li River with three days' total rainfall of 458.4 mm.
Xiliao River rainstorm spreaded in Laoha River, Jiaolai River and the mainstream of Xiliao River, during this drainage area, there was 48800 square kilometers with a rainfall over 100 mm, 20700 square kilometers with a rainfall over 150 mm. Storm center was near Hongshan Reservoir. On 25th, the greatest rainfall was 305.1 mm in Renjiayingzi. Among three days, the areas with a rainfall more than 250 mm covered 3700 square kilometers, more than 200 mm covered 8900 square kilometers, more than 150 mm covered 12800 square kilometers, more than 100 mm covered 17400 square kilometers. The average rainfall near Hongshan Reservoir was 158 mm.
Due to the high strength and extensive scope of the torrential rain, there burst out catastrophic floods in Dalin River in the west of Liaoning province and the upper reaches of Xiliao River in the Inner Mongolia Autonomous Region. In Chaoyang station on Dalin River, there was an incredible one-in-100-year flood-peak of 15600 stere per second, which brought about the collapse in Deligi medium Reservoir on Laohushan River. The rainstorm in the upper reaches of Xiliao River contributed to a catastrophic flood with an average speed of 12700 steres per second, over what it was desighed for the flood flow once in a million years, which had increased by 1.8 times from 11800 stere per second to 25900 steres per second in 1964.
The information is provided by Disaster Risk Reduction Knowledge Service.
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