为了定量评估荆江三口、湘资沅澧四水以及区间来水洪水入湖时洞庭湖内部超额洪量分布情况,以长江干流螺山站、东洞庭湖七里山站、南洞庭湖鹿角站、西洞庭湖南咀站及小河咀站等分别作为区域出口控制断面,建立洞庭湖洪水水文模型,利用1996年、1998年、2017年典型洪水数据率定参数,计算三峡水库运行前后再现1954年洪水(长江防御目标洪水)时洞庭湖内部超额洪量分布情况。研究结果表明三峡水库调洪作用明显,但遭遇目标洪水时城陵矶附近仍有215亿m³超额洪量,且洞庭湖要承担143亿m³超额洪量,其中西洞庭湖、南洞庭湖、东洞庭湖分别承担26亿、62亿、55亿m³超额洪量,该结果与西、南、东洞庭湖区蓄洪垸蓄洪总量相当。本研究结果可为长江中游防洪布局优化提供技术参考。

To quantitatively assess the distribution of excess flood volume in Dongting Lake during the inflow of floodwaters from the Jingjiang River's three diversion outlets, as well as the Xiangjiang River, Yuanjiang River, Zijiang River, and Lishui River, we establish a regional flood routing model. Our model focuses on key control sections, namely the Luoshan station in the Yangtze River's main stream, the Qilishan station in East Dongting Lake, the Lujiao station in South Dongting Lake, and the Nanzui and Xiaohezui stations in West Dongting Lake. By calibrating the parameters using typical flood data from 1996, 1998, and 2017, we calculate the distribution of excess flood volume within Dongting Lake during the 1954 flood (defense target flood for Yangtze River) before and after the Three Gorges operation. The results highlight the apparent flood regulation effect of the Three Gorges reservoir. However, even when facing the target flood, an excess flood volume of 21.5 billion m³ remains near Chenglingji, with Dongting Lake bearing an excess of 14.3 billion m³, among which the West Dongting Lake, South Dongting Lake, and East Dongting Lake bear excess flood volumes of 2.6 billion m³, 6.2 billion m³, and 5.5 billion m³, respectively. This result is equivalent to the total flood storage volume of the storage embankments in the Dongting Lake area. The findings serve as a technical reference for optimizing flood control layout in the middle reach of the Yangtze River.