Temporal and spatial variations of sediment rating curve in Songhua river basin and their implications.

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Tuesday 30 june 2015

12:51 - 12:54h at Mississippi (level 1)

Themes: (T) Sediment management and morphodynamics, (ST) Sediment transport mechanisms and modelling, Poster pitches

Parallel session: Poster pitches: 5A. Sediment - Erosion

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This paper aims at exploring the relationship between water discharge and suspended sediment concentration (SSC) in the Songhua river basin, located in the northeast of China. Based on daily discharge and suspended sediment concentration (from April to October) recorded at four gauging stations (Jiangqiao, Dalai, Harerbin and Jiamusi) on the main stem channel during the time periods 1955~1987 and 2005 ~2010 and the annual runoff and sediment data from 1955-2010, the conventional statistical method was used. The results indicate that in the daily time scale an downward parabolic opening was found to describe the relationship between water discharge and SSC before to a certain magnitude of discharge (about 5000 m3/s) However after this order magnitude, the relationship between water discharge and SSC is difficult to determine, which is mainly due to the impact of the sequences of occurrence of bigger flood. The flow corresponding to the maximum of SSC is increasing along the stream. The decrease of SSC with increasing discharge corresponds to the cross-section shape suddenly broadening. In the annual time scale, the sediment rating curve presents a power function. It indicates that sediment transport regime in the Songhua river basin was influenced by the complex processes of water and sediment inputs from the upstream and also by the channel boundary conditions. Although an obvious decline in runoff and almost no change in sediment transport due to climate change and enhanced human activities, the sediment transport regimes during 1955~2010 did not change.