During July 26th to 28th in 1981, the mountain boarder areas of Gai county, Fucheng county and Xinjin county those three counties which in the south of Liaoning province , Xiongyue River, Liguan River, Fuzhou River and upper reaches of Biliu River, the southern tip of Qianshan mountain, had an extraordinary rainstorm, rare floods and mudslides had been formed. Old Hat Mountain in the center of rainstorm, its main peak is 848.3 meters high; the mountain range is southwest-to-northeast direction; the elevation is 200 to 500 meters, and the vegetation is good. All the above rivers originate from the Old Hat Mountain; the river bed gradient is large, cross section is narrow, and the current is swift. Rainstorm center located in Tongyi commune's Tangjia village in Xinjin county, individual rainfall (14 a.m in July 26th to 20 a.m in July 28th) was 768.9 mm, it was an extraordinary rainstorm in very short time, small area, and very intense; it caused flash floods and mudslides; it caused 664 people died and shenyang railway was suspended for 13 days; some areas suffered devastating disasters.
Rainfalls process
Extraordinary rainstorms started from 14 a.m on July 26th and ended in 20 a. m on 28th, it took 54 hours , rainstorm mainly concentrated on 27th, according to the data of 61 rain stations in the rain area, the rainfall on 27th occupied 85% of the rainfall in three-day. Rainstorm center was located in the east of Changda railway from Xinjin to Gai county, Xijiu station recorded the maximum 24 hours rainfall of 581.5 mm, three-day rainfall was 644.2 mm. Near the Xijiustation, the investigation into Tangjia village that its three-day rainfall was 768.9 mm, 24 hours rainfall was 745.8 mm, the heavy rainfall was extremely rare which nearly the maximum 24 hours of rainfall measured in the whole province. The intensity of this rainstorm is very strong, the largest rainfall intensity in 24 hours rainfall was from 23 a.m in 27th to 4 a.m in 28th, average hourly rainfall was 50~ 60 mm. The actual measurement of Xijiu station in six hours was 395.0 mm, in three hours was 233.0 mm, it reached 116.5 mm in one hour. Broke the highest record in this aera.
The cover area of this extraordinary rainstorm was relatively small. The area of covered land which rainfall in three days above 100 mm was about 22 thousand square kilometers, the area that rainfall above 200 mm was 3830 square kilometers, the area that rainfall above 300 mm was 1762 square kilometers, the area that rainfall above 400 mm was 638 square kilometers, the area that rainfall above 500 mm was 262 square kilometers, the area that rainfall above 600 mm was 118 square kilometers, the area that rainfall above 700 mm was only 19.2 square kilometers .
This extraordinary rainstorm was under the situation of radial high pressure stability circulation in the eastern coast of our country, due to No.7 and No. 8 of the two landing typhoons in the low pressure moved counterclockwise to north, and interacted with the cold air in the west, added the convergence lifting effect of Old Hat Mountain topography, formed the result of the successive influence of several mesoscale strong rain groups.
The information is provided by Disaster Risk Reduction Knowledge Service.
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