Author(s): Jianguo Chen; Cuixia Chen; Dangwei Wang
Linked Author(s): Jianguo Chen
Keywords: Reservoir sedimentation; Channel erosion; Bankfull discharge; Water level; Efficiency of channel erosion
Abstract: Based on the field data of the Xiaolangdi Reservoir and Lower Yellow River from 1999 to 2018, this paper analyzes reservoir sedimentation and its Influence on channel in the Lower Yellow River during the nearly 20 years operation of the Xiaolangdi Reservoir. The result shows that from 1999 to 2018, the total deposition of Xiaolangdi Reservoir reached 3.488×109m3, only 26.7% of the incoming sediment load could be sluiced out of the reservoir. Under the new conditions of incoming runoff and sediment, the Lower Yellow River unavoidably suffers erosion. From 1999 to 2018, the whole erosion of the river amounted to 2.92×109 t. The erosion in flood season is 61.1% of the annual erosion, about 83.6% of the erosion occurs in upper reach of the river covering a length of 495 km. The efficiency of channel erosion becomes weaker and weaker. The smallest bankfull discharge of the Lower Yellow River in the post-flood season were increased from 1800 m3/s in 2002 to 4300 m3/s in 2018. The water levels corresponding to the discharge of 3000 m3/s in the pre-flood season of 2018 obviously dropped down by 1.67m-3.20m in the Lower Yellow River, as compared with those in the pre-flood season of 1999. The surface bed materials in 2018 were nearly two times as coarse as those in 1999. Further research shows that, the increased flow energy coursed by 1m3 sedimentation in the Xiaolangdi Reservoir are capable to scour 0.84t sediment in the downstream channel, therefore, the sediment detention by reservoirs are still one of the most effective measures for sedimentation reduction in the Lower Yellow River.
Year: 2024