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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Sediment management and morphodynamics : Effects of delta extension on base level rising of the lower yellow river
Effects of delta extension on base level rising of the lower yellow river
nnel avulsion and extension of the Yellow River delta in response to sediment deposition caused by
heavy sediment loads entering the estuary, the water stage at a discharge of 3000 m3/s (denoted by H3000) at Lijin station
(the endpoint of the lower Yellow River) rose by 2.5 m between 1950 and 2000, with an average rate of 5 cm per year.
The water stage or channel bed elevation at Lijin station acts as the local base level of the lower Yellow River (LYR), and
its rise is significant for the long-term evolution of the upstream channel. Impacts of delta evolution on the changes of
H3000 at Lijin were analysed in this study. The results showed that whenever channel avulsion occurred, the river length
decreased abruptly and the channel slope increased. The channel length then increased at a decreasing rate, while the
slope decreased exponentially with time and reached an equilibrium value after 5 to 6 years. This phenomenon indicates
a significant characteristic of the delayed response of the fluvial system. Based on differences in the evolution of channel
reaches upstream and downstream of the diversion point at the Yellow River delta, two generalized models for the
longitudinal changes of the extended delta channel were proposed. An equation for calculating H3000 at Lijin was
developed by using the delayed response model for modelling morphological responses of fluvial rivers to perturbations.
H3000 at Lijin during the last 60 years was calculated well by the proposed method, which considers the impacts of water
and sediment conditions and delta evolution on the changes of the local base level of the LYR. This study helps to
increase the understanding of the interactions of delta evolution and upstream channel reaches where high sediment
yield is present.Form Required :
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Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Sediment management and morphodynamics
Date Published : 20/08/2015
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