干旱区生态环境知识资源中心

The tributary-trunk stream relationship is investigated with respect to hyperconcentrated flows and coupled wind-water processes in the Yellow River, China. Ten small tributaries that drain only 3% of the total drainage area of the trunk stream transport large amounts of relatively coarse sediment from the desert to the trunk stream during hyperconcentrated floods. The resultant strong sedimentation often jams the trunk stream, leading to serious disasters. This study reveals the cause of this interesting phenomenon and proposes countermeasures for disaster reduction. A typical sediment-jamming event (SJE) in July 1989 was thoroughly analysed based on the observational data, including the beginning, development and final stages of the event. An index of the geomorphologic effectiveness of the tributary on the trunk stream and a number of indices describing SJEs and the influencing factors are adopted, based on which a discrimination relationship for the occurrence of SJEs is established and some statistical relationships are also established. The SJE’s hydrological and geomorphologic impacts are discussed at short timescales (from several days to one month) and at long time scales (up to 46years). The results may help to gain a new insight into the study of the tributary-trunk stream relationship, and provide useful information for sediment management and disaster-reduction planning in the drainage basin. Countermeasures are suggested to reduce the channel sedimentation and the risk of sediment-jamming disaters.