During the flood period in 1957, especially from July to August, there were frequently rainfalls in Songhua River basin, most areas of which, had been dull and rainy lasting almost 40 days. The right tributary of downstream of Nen River as well as Second Songhua River Basin, broke out heavy rains and storms many times which led to deluges and catastrophic floods in main rivers of that basin.
There were catastrophic floods which can not be seen in 20 or even 50 years in the upstream of Songhua River, Yalu River, the tributary of Nen River, Chouer River and Taoerhe. In Haerbin station on the main river of Songhua River, the flood was the fiercest one since the establishment of PRC, whose maximum flow rate was measured to be 12200 steer per second. Flood-peak discharge was adjusted to 14300 taking the store and regulates the effect of Fengman reservoir into account, ranking second since 1898 just after the level in 1932.
Process of precipitation
Precipitation was largely in July and August rather than June. From the start of July to the end of August, most areas in Songhua Basin had heavy rainfall lasting almost 40 days and even 45 days, during which, there were ten hard rains or rainstorms.
On 15th July, whole Songhua River Basin was rainy while was no uniform for different areas, it reached to 50 mms to 100 mms in upstream of Nen River and Kachahe Basin of Lalin River as well as upstream of Huifa River and Yinma River.
On 15th to 16th July, one local rainstorm centralized in Keshan county distributed among Wuyuerhe and Nemorhe, the tributaries of Nen River, whose maximum rainfalls in 24 hours rose to 220.7 mms on 15th July.
On 24th to 25th July, the belt of downstream of YaLuhe, Qiqihaer merged with Taoerhe Heidimiao rained heavily. On 24th, the torrential rain centralized in Heidimiao, whose daily rainfall was 89.5 mms, the daily rainfalls in other areas all more than 50 mms. On 25th, there were rainstorms in Panshi station on the Second Songhua River, Tudingzi station on Mushihe and Taipingshan station, whose daily rainfall was 63.9 mms.
From 26th to 30th July, the storm focused on Yitonghe Basin with the daily rainfall of 60 mms to 80 mms. In 27th, the storm was mainly in Taoerhe and Huolindun Basin of Nen River with the daily rainfall of 500 mms to 100 mms and other three days did not suffer the heavy rain.
From 1st to 5th August, the storm principally in middle and lower reaches as of Nen River as well as its tributaries: Ganhe, Yinhe, Yaluhe, Taoerhe, Huolinhe. Chaersen station of Taoerhe, with the rainfall of 136.9 mms, had the most moisture. During this period, there were extremely heavy rains in Second Songhua River and Yitonghe, for example, Wongke station of Yitonghe had a 143.6 mms rainfall.
On 8th to 9th August, the left tributary of Nen River merged with upstream of Hulanhe rained heavily. The torrential rain centralized in Nanguan station of Hulanhe, whose rainfall was 110 mms, the daily rainfalls in Longanqiao station of Wuyuhe was 62.1 mms.
From 10th to 15th August, moisture started from Keluo River, Ganhe River, Nemor River on upstream of Nen River and then spread to Taoerhe, the downstream of Nen River, and wetland on the north of the river. The rainfall in Tongmeng statin of Nen River was 103 mms during 10th to 13th, in Hezhen station of Taoerhe was 136.9 mms during 10th to 14th, in wetland center station of northern Nen River was 117.6 mms during 11th to 15th.
From 18th to 19th August, the storm principally in the Second Songhua River, Yinma River, lower reaches of Yitonghe as well as areas alone Sonhua River. It was not raining heavily with a rainfall of 25 mms to 50 mms, and the maximum was 78 mms in Songhuajiang Station.
From 20th to 22nd August, the storm principally in the Second Songhua River, upper reaches of Lalin River. In 21st, there was the heaviest rain with all Mudan River Basin above 100 mms and being 154.4 mms in Sijitong station.
From 26th to 29th August, there was a wide scope of rainy regions. In lower reaches of Nen River and the Second Songhua River as well as Hulan River, Lalin River, Mayi River, middle and lower reaches of Mudan River, were less than 50 mms in retrospect of rainfall. As for the maximum, Changwu station on the wetland of northern Nen River was 146 mms and Lanxi station of Hulan River was 117 mms.
All the 10 rains were centralized in the three rains from 24th July to 5th August archly in Yaluhe, Chuoer River, Taoer River, the right tributaries of Nen River as well as Yitonghe which lies in the middle of Jilin province, and the area of which more than 100 mms rainfall reached to 500 thousand square kilometers, and the another rain from 20th to 22nd . Chaersen station of Taoer River suffered 304 mms rainfall during 24th July to 5th August, 1.19 times than what the sum of July and August were 254.7 mms, which brought out the big flood in right tributary region and middle and lower reaches of Nen River.
On 20th to 22nd , the rain caused by the proceed north typhoon mostly distributed in the basins of Second Songhua River, Mudan River, Yalu River on the east part of Northeast China, which contributed to deluges in Second Songhua River and Mudan River.
During this progress, there were over 40 days in July and August raining in the whole Songhua River Basin. Mudan River Basin, the Second Songhua River region and the middle and lower reaches of Nen River region were the main rainy regions, and the July and August’s rainfall of the latter two areas were more than 200 mms generally.
Major features of the rain of this flood season were the lasting time and its frequency as well as the rainstorms and torrential rains during which.
Keshan station on Nen River Basin, on 15th July, reached to 150 mms in the maximum hour, 201.2 mms in the maximum six hours, and 220.7 mms the whole day. From 1st to 5th , August, the rainfalls in Chaersin station of Taoer River and Nianzi station of Yaluhe were 136.9 mms and 111.2 mms exceeded what they were for many years in August of 103.9 mms and 107.8 mms. From 24th July to 5th August, the total rainfall in Chaersin station was 304 mms, 1.19 times than 254.7 mms, what it used to be for a long time. Some other stations in Taoer River Basin were more than 250mms.
From 20th to 22nd August, it was heavy rains in Mudan River Basin, especially in 21st, when the rainfall rose to more than 100 mms. The daily rainfall in Sijitong station was 154.5, 1.2 times than where it used to be in August.
From 24th July to 5th August, and from 20th to 22nd August, it was heavy rainy in the area of Fengman Reservoir and Yitonghe Basin. During the former moisture, Mingli station on the upper reach of Fengman Reservoir, Liujiazi station and Xinlicheng on Yitonghe, were more than 200 mms and other stations all above 100 mms. As for the latter period, the rainfall in Fengman reservoir was 50 mms to 100 mms.
The information is provided by Disaster Risk Reduction Knowledge Service.
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