摘要
枢纽蓄水运用改变了坝下河段的水沙条件,其中径流过程的变化,改变了不同流量级水流的水动力条件和造床能力,输沙量的改变,是引发坝下游河床调整的关键。根据三峡和丹江口下游近坝河段实测资料,分析了相对窄深,低水分汊、两岸约束很强,以及低水分汊、两岸约束很弱等3种类型河段在蓄水以后冲淤调整特点,在此基础上分析了其冲淤变化对航道条件的影响。结果表明:当河段相对窄深时,河段冲刷主要为下切;当河段为相对宽浅的低水分汊河段且河岸约束较强时,蓄水以后的冲淤变化主要体现为江心洲滩的冲淤调整、汊道深泓高程差的冲淤调整,并引起主支汊分流比的调整;当河段为较为宽浅的低水分汊河段且河岸约束相对较弱时,则冲刷调整不仅限于分流比的调整,甚至会导致大的分汊格局的调整。无论如何调整,都有可能引起新的航道问题。
The reservoir operation changes water and sediment factors at the downstream reach. And the change of runoff process is the key factor which initiated river bed adjustment in downstream of the dam. It changes the hydrodynamic condition, the bed building ability and sediment discharge of different rate of flow. Based on the observed data of the near-dam reach downstream the Three Gorges and Danjiangkou river, this paper analyzes the characteristics of erosion and deposition adjustment after impoundment in different river patterns, and the impact on navigation condition. The result shows that the erosion presents as incision when the riverbed is relative narrow and deep; To the low-water branching reach with strong boundary conditions where the riverbed is wide and shallow, the scour and deposit variation characteristics mainly presents as erosion and deposition adjustment of river island, height deviation of thalweg in the inlets and the adjustment of split ratio after impoundment; To the low-water branching reach where the riverbed is wide and shallow and the lateral boundary conditions are weak, the scour and deposit variation characteristics is not restricted to the adjustment of split ratio, and the pattern of the braided reach may even be changed. It will bring new channel problems at all adjustments.
出处
《水运工程》
北大核心
2008年第7期109-114,共6页
Port & Waterway Engineering
基金
国家科技支撑计划项目(2006BAB05B03-05)
973项目(2003CB415205)
国家自然科学基金项目(50479036)
关键词
近坝段
再造床
低水分汊
航道
near-dam reach
river reformation
low-water branching reach
navigation channel
