摘要
The operation of large-scale reservoirs have modified water and sediment transport processes,resulting in adjustments to the river topography and water levels.The polynomial fitting method was applied to analyze the variation characteristics of water levels under different water discharge values in the Jingjiang reach of the Yangtze River from 1991–2016.The segregation variable method was used to estimate the contributions of the varied riverbed evaluation,the downstream-controlled water level,and the comprehensive roughness on the altered water level at an identical flow.We find that low water levels in the Jingjiang reach of the Yangtze River from 1991–2016 are characterized by a significant downward trend,which has intensified since 2009.Riverbed scouring has been the dominate factor causing the reduced low water level while increased roughness alleviated this reduction.From 1991–2016,there was first a decrease followed by an increase in the high water level.The variation characteristic in terms of the'high flood discharge at a high water level'before 2003 transformed into a'middle flood discharge at a high water level'since 2009.The increased comprehensive roughness was the main reason for the increased high water level,where river scouring alleviated this rise.For navigation conditions and flood control,intensified riverbed scouring of the sandy reaches downstream from dams enhanced the effects that the downstream water level has on the upstream water level.This has led to an insufficient water depth in the reaches below the dams,which should receive immediate attention.The alteredvariation characteristics of the high water level have also increased the flood pressure in the middle reaches of the Yangtze River.
The operation of large-scale reservoirs have modified water and sediment transport processes, resulting in adjustments to the river topography and water levels. The polynomial fitting method was applied to analyze the variation characteristics of water levels under different water discharge values in the Jingjiang reach of the Yangtze River from 1991–2016. The segregation variable method was used to estimate the contributions of the varied riverbed evaluation, the downstream-controlled water level, and the comprehensive roughness on the altered water level at an identical flow. We find that low water levels in the Jingjiang reach of the Yangtze River from 1991–2016 are characterized by a significant downward trend, which has intensified since 2009. Riverbed scouring has been the dominate factor causing the reduced low water level while increased roughness alleviated this reduction. From 1991–2016, there was first a decrease followed by an increase in the high water level. The variation characteristic in terms of the “high flood discharge at a high water level” before 2003 transformed into a “middle flood discharge at a high water level” since 2009. The increased comprehensive roughness was the main reason for the increased high water level, where river scouring alleviated this rise. For navigation conditions and flood control, intensified riverbed scouring of the sandy reaches downstream from dams enhanced the effects that the downstream water level has on the upstream water level. This has led to an insufficient water depth in the reaches below the dams, which should receive immediate attention. The altered variation characteristics of the high water level have also increased the flood pressure in the middle reaches of the Yangtze River.
作者
CHAI Yuanfang
YANG Yunping
DENG Jinyun
SUN Zhaohua
LI Yitian
ZHU Lingling
无
柴元方;邓金运;杨云平;孙昭华;李义天;朱玲玲;无(Department of Earth Sciences,Vrije Universiteit Amsterdam,Boelelaan 1085,1081 HV Amsterdam,The Netherlands;State Key Laboratory of Water Resources and Hydropower Engineering Science,School of Water Resources and Hydropower Engineering,Wuhan University,Wuhan 430072,China;State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai University,Nanjing 210098,China;Key Laboratory of Engineering Sediment,Tianjin Research Institutes for Water Transport Engineering,Ministry of Transport,Tianjin 300456,China;Bureau of Hydrology Changjiang Water Resources Commission,Wuhan,430010,China)
基金
National Key Research and Development Program of China,No.2018YFB1600400
Open Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,No.2017491211
Fundamental Research Funds for Central Welfare Research Institutes,No.TKS20200312。
