湄公河与洞里萨湖河湖关系研究

River-lake relationship between Mekong River and Tonle Sap Lake

湄公河是亚洲最重要的跨国水系,洞里萨湖是湄公河最大的通河湖泊,河湖关系非常复杂且一直是国际社会关注的热点问题。利用7个河湖控制站的长系列水文资料,对河湖水位和流量关系,湄公河向洞里萨湖倒灌与洞里萨湖向湄公河补水的特性、条件及成因,湄公河干流来流与洞里萨湖出流的相互顶托作用等进行了分析。分析结果表明:洞里萨湖具有洪枯水期均为近似湖相的特征;湄公河与洞里萨湖的水量交换强度大,每年汛期均会发生倒灌,年均倒灌历时122d,倒灌水量377亿m3,年均补水历时244d,补水水量711亿m3;倒灌与补水的主要水文条件为河湖水位差和洞里萨河的水位,成因机理为河湖间势能和动能的平衡规律;湄公河下泄水量与洞里萨湖出流相互顶托作用强烈,汛期倒灌期间湄公河流量每增加1000m3/s,洞里萨湖水位就会抬高0.14~0.21m,汛末9月中下旬至10月底补水期间洞里萨湖出流每增加1000m3/s,湄公河磅湛站水位就会壅高0.01~0.43m。研究成果可为柬埔寨湄公河三角洲和洞里萨湖治理提供科学依据。

The Mekong River is Asia’s most important transnational water, and the Tonle Sap Lake is the largest lake connected to the Mekong River. The river-lake relationship between them is complicated, receiving worldwide attention. Using long-series hydrological data from seven river-lake control stations, we analyzed the following topics:① relationship between the water level and flow rate;② characteristics, conditions and causes of river flowing backwards into the lake, and being replenished by the water from the lake;③ backwater effects of water flowing to the river mainstream and water flowing out from the lake. The results show that:① the lake has characteristics that are similar to lacustrine facies in flood season and dry season.② water exchange between the river and the lake is extremely frequent;water flowing backwards to the lake occurs in flood season every year with duration of 122 days, and the total volume of 37.7 billion square meters;the average duration to the river is 244 days with total volume of 71.1 billion square meters. Differences in water level between the river and the lake, and the water level of the Tonle Sap River are the two major hydrological conditions for the water exchange, and it is the result of the law of equilibrium in potential energy and kinetic energy between rivers and lakes.③ there is a strong interaction between the water discharged from the river and the lake. For every 1000 m3/s increases for the river during flood season, the water level would rise by 0.14 to 0.21 meters;at the end of flood season from mid-to-late September to the end of October, for every 1000 m3/s increase in the lake, water level of the river would rise by 0.01 to 0.43 meters. This study can provide scientific basis for the comprehensive management of Mekong Delta and Tonle Sap Lake in Cambodia.