Flood composition of main stream belonging to Nenjiang river

With a total length of 1370 km and a basin area of 297 thousand square kilometers, Nenjiang River is the North source of the main stream of Songhua River. The flood in the main stream of Nenjiang River is mainly formed by the runoff from the tributaries on the right side. These tributaries originate from the east slope of Greater Higgnan Mountains. Affected by topography, they are one of the rainstorm centers in the northeast area. Because the middle and upper reaches of the tributaries are in mountainous areas and the runoff is fast and concentrated, which is liable to form a great flood. In the middle reaches of Nenjiang River, we take the Fulaerji Station and the lower reaches of Jiangqiao Station as the control to analyze the regional composition of the major floods.

Peak composition of flood of the Fulaerji Station of Nenjiang River Generally，there are three types of the flood composition in the Fulaerji Station of Nenjiang River. The first is the upstream flood such as 1953、1955、1988 and 1989 and the 30 day flood volume which came from upstream ratio up to 62.6~85.3%. The second is the interval flood. Interval flood peak in 1998 accounted for 76.9% of Fulaerji and the 30day's flood volume accounted for 62.1%; The last is the whole basin flood such as 1969.

Table.1 The peak composition of flood in flood year of the Fulaerji Unit：(m^3/s)

Table.2 The composition of 30day's flood volume in flood year of Fulaerji
Unit：(10⁸m³⁸)