摘要
大型水利枢纽的修建引起了下游河道的冲淤调整,对生态环境、防洪、航运等都有显著的影响。2008年三峡水库175 m试验性蓄水以来,城陵矶以下河段冲刷加剧。为探究水库影响下游河道冲淤调整特征及其驱动机制,分析了城陵矶至九江段河道冲淤分布及断面形态变化特征:2008年以来河道冲淤变化主要集中在基本河槽,其变化占整个平滩河槽的90%以上,且基本河槽冲刷加剧;断面形态表现为河槽冲刷下切、断面趋于窄深化。在此基础上,通过建立2008—2016年河段尺度的基本河槽形态参数与水流输沙能力的经验关系,发现螺山、汉口两站流量分别为29000~31000 m 3/s、31000~33000 m 3/s时,河槽形态与水流输沙能力的相关性最强、造床作用和水流冲刷强度最大,因此,可以认为是2008年以来影响城陵矶至九江段冲淤调整的特征流量。2008年以后,该流量级以下的水流累积造床作用凸显,是冲淤变化部位调整到基本河槽的主要原因;同时,受各站d>0.125 mm粒径组泥沙输沙量大幅度减小、航道整治工程的影响,河槽冲刷加剧。
The construction of a large-scale water conservancy project has caused the adjustment of the scouring and silting of the downstream river channel,which has a significant impact on the ecological environment,flood control and channel transportation.Since the trial experimental impoundment of the Three Gorges Dam in 2008,the downstream erosion of Chenglingji has intensified.To explore the adjust characteristics of scouring and silting and the driving mechanism of the downstream erosion of a river channel during a water control project,the spatial evolution characteristics and transverse morphological variation of the reach from Chenglingji to Jiujiang reach were analyzed.The results show that the scouring of the low flow channel in the Chenglingji—Jiujiang reach has intensified,and the morphological changes since 2008 have mainly been concentrated in the medium flow channel,of which the proportion of the evolution volume accounts for more than 90%;the transvers changes shows scouring and incising,while a sectional view displays narrowing and deepening.On the basis of the established empirical relationship between the reach-scale medium channel dimensions and the accumulated sediment transport capacity in each discharge interval during 175 m experimental water storage period from 2008 to 2016,this paper indicates that the discharge of 29000—31000 m 3/s at Luoshan Station and that of 31000—33000 m 3/s at Hankou Station can be regarded as characteristic discharges corresponding to the average top levels of braided channel bars,which are of morphological significance in constraining the passing flow in the medium flow channel and guaranteeing that the water transport capacity is the strongest.The geomorphic impact of flow below the characteristic discharge was more prominent during 2008—2016;this impact resulted in the adjustment of scouring and silting being mainly concentrated in the medium flow channel.Moreover,river channel erosion has intensified because,in addition to the construction of waterway regulati
作者
张为
吴美琴
李思璇
袁晶
高宇
ZHANG Wei;WU Meiqin;LI Sixuan;YUAN Jing;GAO Yu(State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan 430072,China;Bureau of Hydrology,Changjiang River Water Resources Commission,Wuhan 430010,China)
出处
《水科学进展》
EI
CAS
CSCD
北大核心
2020年第2期162-171,共10页
Advances in Water Science
基金
国家自然科学基金资助项目(51779184,51479146)。
关键词
基本河槽
冲淤调整
水沙条件
特征流量
三峡水库
medium flow channel
adjustment of scouring and silting
water and sediment conditions
characteristic discharge
Three Gorges Dam
