摘要
拉萨河上游直孔水库于2006年建成以来,水库拦沙与下泄清水冲刷使下游卵砾石河床逐渐粗化,其粗化程度、范围和平衡状况有待研究。2018年4月的野外考察和现场观测拉萨河直孔水库上下游辫状河道,选取5个观测点,测量河床表面卵石中值粒径,同时利用无人机30 m低空航测,经过图像处理生成实测区域的高分辨率河床洲滩地形,计算洲滩表面粒径和相对粗糙度的空间变化。结果表明,采用无人机航测方法可较高精度地提取河床表面的卵石粒径级配,中值粒径的平均误差为18.7%。由于水流冲刷和分选作用,直孔大坝下游1 km河段内河床粒径粗化已完成,坝下游10 km范围内沿程粒径减小,至坝下游22 km后河床粒径逐渐恢复正常。
Since its completion in 2006, the Zhikong Reservoir on the upper Lhasa River has trapped incoming sediment and released clean water, causing a relatively fast coarsening of the gravel riverbed in the downstream channel;but the degree and scope of the coarsening and the equilibrium status of gravel bed are not understood yet. In April 2018, we conducted a field survey of the riverbed around the reservoir focusing on five sites and manually measuring the median particle size of gravels and pebbles on the riverbed surface, and adopted unmanned aerial vehicles(UAV) taking photographs at a height of 30 m. Through image processing and generation of the high-resolution terrain data, we calculated spatial variations in the gravel particle size and relative roughness of the bar surface. Results show that the UAV aerial survey method can extract the particle size of gravel bed surface in good accuracy, and the mean error in median particle size calculations is about 18.7% in comparison with the manual measurements.Owing to flow scour and sorting, the coarsening in the river section of 1 km long below the dam has reached its equilibrium;and the particle size decreases along the course in the 10 km long section below the dam, and gradually recovers to the normal up to a distance of 22 km below the dam.
作者
鲁瀚友
李志威
胡旭跃
胡铁松
袁昕亚
LU Hanyou;LI Zhiwei;HU Xuyue;HU Tiesong;YUAN Xinya(School of Hydraulic Engineering,Changsha University of Science&Technology,Changsha 410114;Key Laboratory of Water-Sediment Sciences and Water Disaster prevention of Hunan Province,Changsha 410114;State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan 430072)
出处
《水力发电学报》
EI
CSCD
北大核心
2020年第8期104-111,共8页
Journal of Hydroelectric Engineering
基金
国家自然科学基金项目(91647204,51709020)
关键词
床沙粒径
卵石洲滩
水库影响
相对粗糙度
无人机航测
riverbed particle size
gravel bar
dam effect
relative roughness
UAV aerial survey
