洞庭湖区超标准洪水数值模拟研究

Study on super-standard flood situation in Dongting Lake area

  • 摘要: 洞庭湖区是我国洪涝灾害频发的地区之一,随着近些年来极端天气越来越频繁,研究洞庭湖区在遭遇历史极端洪水下的防洪形势极具现实意义。以1870年、1935年、1954年长江洪水为研究对象,通过建立长江、洞庭湖及蓄滞洪区一二维耦合水动力模型,在现有地形及工程措施条件下,对洞庭湖区的水位及超额洪量进行模拟计算。 结果表明:三峡及上游水库群补偿调度条件下,若遭遇1870年、1935年和1954年洪水,荆江附近及城陵矶附近的超额洪量大幅下降,再结合荆江地区及城陵矶附近蓄滞洪区的运用,洞庭湖区可安全度汛。三峡水库调蓄使枝城洪峰流量大幅下降,松滋口、太平口、藕池口(以下称为三口)洪峰流量也随之下降,洞庭湖区各站水位有所降低;蓄滞洪区分洪运用降低了莲花塘水位,荆江水面比降加大,三口洪峰流量进一步下降,受上游来水减少及下游水位降低的影响,湖区水位进一步下降。通过定量预测特大洪水长江中游及洞庭湖区防洪情势,可为洞庭湖治理提供科学依据,为提升湖区防洪减灾管理能力奠定基础。

     

    Abstract: Dongting Lake area is one of the areas with frequent flood disasters in China. With the increasing frequency of extreme weather in recent years, it is of great practical significance to study the flood control situation of Dongting Lake area under historical extreme floods. Taking the floods of the Yangtze River in 1870, 1935 and 1954 as the research object, by establishing a one-dimensional and two-dimensional coupled hydrodynamic model of the Yangtze River, Dongting Lake and flood storage and detention area, the water level and excess flood in Dongting Lake area are simulated under the conditions of existing topography and engineering measures. The results show that under the condition of compensation operation of the Three Gorges and upstream reservoirs, if the floods in 1870, 1935 and 1954 occur, the excess flood volume near the Jingjiang River and Chenglingji decreases significantly. With the application of flood storage and detention areas in Jingjiang area and Chenglingji area, Dongting Lake area can safely stand the flood. The regulation and storage of the Three Gorges reservoir has greatly reduced the peak discharge of Zhicheng, the peak discharge of the three rivers in Southern Jingjiang has also decreased, and the water level of each station in Dongting Lake area has decreased. The application of flood diversion in the flood storage and detention area has reduced the water level of Lianhuatang, increased the water surface gradient of the Jingjiang River, and further reduced the peak flow of the three rivers in Southern Jingjiang. Due to the reduction of upstream and downstream water levels, the water level in the lake area has further decreased. By quantitatively predicting the flood control situation of the middle reaches of the Yangtze River and Dongting Lake area, the study provides a scientific basis for the governance of Dongting Lake and lays a foundation for improving the management ability of flood control and disaster reduction in the lake area.

     

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