摘要
小型水坝随着服役时间的增长,其面临的安全、经济和生态方面问题日益突出,针对一些修复价值较低的病险水坝,实施降等或报废拆除已成为一种综合最佳的管理措施。拆坝后,原库区大量淤沙无控释放将改变原有河道形态,对水生生物栖息地造成影响。为预测拆坝后河道在不同时间尺度上的变化特征,以长江流域乌江水系内的西河水坝为研究对象,建立二维水沙数学模型,分别研究了拆坝后水沙输运造成的短期和长期河床形态变化。结果表明:拆坝后短期内,坝址上游主河道发生了强烈的冲刷下切,且水库淤沙前缘部分出现了显著的淤积抬高,相比而言,坝址下游河床变化并不明显,只有坝下河段及河口附近出现较显著的泥沙淤积;在拆坝后长期的河床演变过程中,坝址上下游河道均发生了不同程度的冲刷下切,拆坝2年后下游河床逐渐趋于稳定,而上游主河道由冲刷下切转化为冲淤交替的演变趋势,河床形态不断调整变化。本研究可为病险坝和小水电报废拆坝后的河道治理、水生生物栖息地修复提供参考依据。
As the serving time of low-head dams prolonged,security,economy and ecology issues of these dams have become increasingly prominent.For small dams with little repair values,forced retirement or demotion would be the best management measure.After removal of the dam,large amounts of sediment in the reservoir will be released,which leads to the change of river morphology hence affecting aquatic habitats.To predict the evolution characteristics of river channel in different time scales,Xihe dam in Wujiang drainage system was chosen as an example.By establishing two-dimensional sedimentation model,riverbed evolution in different time scales after dam removal was simulated and studied.The results showed that:in the short term after dam removal,the upstream of the dam experienced a strong scour,and sedimentation appeared in the front part of the reservoir delta;in contrast,the riverbed changes in the downstream of the dam was not obvious,only a small amount of sediment deposition occurred near the estuary and downstream of the dam;as for the long-term evolution after dam removal,both the upper and lower reach experienced different degrees of scour.After 2 years of dam removal,the morphology of downstream riverbed tended to be stable,while the evolution of the upstream transformed from scour to alternating deposition and erosion,and the riverbed morphology was under constantly adjusting.Results of our study can provide important basis for further river channel managements,aquatic habitat restorations after removal of sick dams and small hydropowers.
作者
唐磊
何术锋
莫康乐
林育青
马君秀
陈求稳
TANG Lei;HE Shufeng;MO Kangle;LIN Yuqing;MA Junxiu;CHEN Qiuwen(Nanjing Hydraulic Research Institute,Nanjing 210029,China)
出处
《水科学进展》
EI
CAS
CSCD
北大核心
2019年第5期699-708,共10页
Advances in Water Science
基金
国家重点研发计划资助项目(2016YFC0502205)
国家杰出青年科学基金资助项目(51425902)~~
关键词
拆坝
水沙模型
河道演变
溯源侵蚀
沉积
dam removal
sedimentation model
channel evolution
headward erosion
deposition
