As the formation of runoff in Northeast of China roots in rainfall, the distribution of annual average depth of runoff is as similar as precipitation distribution. In the high level area, southeast of Northeast of China, the depth of runoff rises to 200~500 mms, as for some local areas, such as the middle and lower reaches of Yalu River which reaches to 500~700 mms and runoff of upstream of Yalu River as well as Baitoushan Tianchi of Changbai Mountains reaches to 500 to 600 mms. In Dudan River, Lalin River, Tangwang River and the second Songhua River, the amount of runoff is about 300 to 500 mms. In the extensive regions of Northeast of China on the west, the south, and the southwest, the number of runoff is merely 100 to 200 mms. in the plain area of middle and lower stream of Nenjiang River merges with upstream of Xiliaohe River, the annual amount of runoff is below 50 mms, and there are a lot of areas even less than 25 mms.
The uneven distribution of annual change in Northeast of China is more obvious than that of rainfall, what’s more, there are prominent persistent features in alternating change of wet and dry seasons according to series analysis material of Haerbin Station in Songhuajiang Basin. The annual average runoff velocity in Ha'erbin hydrometric Station between 1898 to 1982 runs 1304 cubic meters per second, while between 1898 and 1927, that is quiet withered, only 885 cubic meters per second, the same phenomenon happened in Eergu'Na River in the upstream of Heilongjiang River.
There is a great different distribution of annual runoff, volume of runoff of wet season from June to September makes up over 70% of the whole year, from July to August, that's amount is between 50% and 70% of the whole year. In winters, middle and small rivers even are setting off in dry seasons.
The rivers flow of 1500 cubic meters per capita in the Northeast of China, about 60.6% of the national per capita. Rivers flow of 590 cubic meters per acre, and about 31.20% of the national average, were clearly lower than the national average level. Distribution of average river runoff over many years by provinces, Liaoning province is 32.5 billion cubic meters and 830 cubic meters per capita, per acre 627 cubic meters; Jilin province is 34.5 billion cubic meters and 1414 cubic meters per capita, per acre 584 cubic meters; Heilongjiang province is 64.7 billion cubic meters and 1782 cubic meters per capita, per acre 487 cubic meters; Four East League of Inner Mongolia of 33.5 billion cubic meters, 3225 cubic meters per capita, per acre 920 cubic meters.
The information is provided from Disaster Risk Reduction Knowledge Service.
Comment list ( 0 )
