长江全流域大洪水下三峡水库对洞庭湖区防洪贡献分析

基于长江中下游一、二维耦合水动力学模型，以1954和1998年洪水为典型，模拟了三峡水库调蓄前后洞庭湖区的洪水过程，定量分析了三峡水库对洞庭湖区防洪的贡献.结果表明：在长江发生1954和1998年全流域大洪水期间，三峡水库实施兼顾对城陵矶河段的防洪补偿调度，可有效缓解荆南三口河系及湖区的防洪压力，减少荆南三口1.58%和0.61%的分洪量，削减荆南三河24.6%和18.4%的洪峰流量.洞庭湖区最高水位降低0.50~0.93和0.51~0.82 m，削减值空间上呈现北强南弱、东高西低的分布格局.遇1954年长江中下游防御型大洪水，三峡水库调蓄后洞庭湖区超额洪量可减少43.2亿m³，但仍存在大量的超额洪量需要妥善处理.

Analysis on flood control contribution of the Three Georges Reservoir for the Lake Dongting area under basin-wide severe floods of Yangtze River

Based on the one- and two-dimensional coupled hydrodynamic model of middle and lower reaches of the Yangtze River, taking 1954 and 1998 flood as the typical floods, the flood processes of the Lake Dongting area before and after the flood control operation of the Three Gorges Reservoir were simulated. Quantitative analysis was carried out for the flood control contribution of the Three Georges Reservoir for the Lake Dongting area. The results indicate that, during the basin-wide severe flood period of the Yangtze River such as 1954 and 1998 floods, after the operation of the Three Gorges reservoir, the flood control pressure of the three rivers in southern of Jingjiang River and the Lake Dongting area was effectively alleviated. About 1.58% and 0.61% of the flood diversion volume and 24.6% and 18.4% of the peak discharge of the three rivers in southern of Jingjiang River could be reduced; in addition, 0.50-0.93 and 0.51-0.82 m of the maximum water level of the Lake Dongting area could be reduced. From the perspective of spatial distribution, the decrease value shows a pattern that the north and east was stronger than the south and west. Under the extreme floods the Yangtze River such as 1954 flood, the flood volume in the Lake Dongting area could be decreased by 4.32 billion m³ after the Three Gorges Reservoir operation, whereas excessive floods still should be handled properly.