洞里萨湖是湄公河最大的连通湖泊,湄公河与洞里萨湖水量交换特征一直是国际社会关注的热点问题,但相关研究成果较少。利用4个河湖控制站的长系列水文资料,分析了湄公河与洞里萨湖水量交换特征,结果表明:湄公河与洞里萨湖的水量交换强度大,洞里萨湖对湄公河径流调峰补枯作用明显,每年汛期5—9月份均会发生倒灌,1995—2011年年均倒灌历时122 d,倒灌水量377亿m³,占湄公河干流同期来水的14.4%,倒灌洪峰流量8 402 m³/s,占干流同期来水的20%,其中7—9月份倒灌水量占全年的88.6%;汛后10月份—次年4月份洞里萨湖向湄公河补水,年均补水历时244 d,补水水量711亿m³,是湄公河倒灌入湖水量的1.96倍,占湄公河下游同期来水的29.9%,其中10月份—次年1月份补水量占全年的83.1%。年倒灌历时、水量与洪峰流量,年补水历时、水量与峰值的年际变化较小,变幅分别为76 d、283亿m³、6 095 m³/s和76 d、474 亿m³、4 677 m³/s,变差系数为0.07～0.24。倒灌、补水水量不仅与湄公河和洞里萨湖的来水大小有关,还受到河湖水位差及洞里萨河水位等因素影响。研究成果可为湄公河三角洲和洞里萨湖区治理提供科学依据。

Tonle Sap Lake is the largest river-connected lake of Mekong River. The water exchange between Tonle Sap Lake and Mekong River has always been a major focus in the international community. Long series of hydrological data of four river-lake controlling stations were employed to analyze the time and magnitude variation characteristics of the water exchange between Mekong River and Tonle Sap Lake. Results show that the water exchange between Mekong River and Tonle Sap Lake is highly intensive. Tonle Sap Lake has obvious peak clipping and dry replenishing effect on the runoff of Mekong River. During flood season (May to September), backward flow from Mekong River to Tonle Sap Lake lasts 122 days on average every year, with a total volume of 37.7 billion m³, accounting for 14.4% of the incoming flow from upper Mekong River in the same period; in particular, the backwater volume from July to September occupies 88.6% of the total annual backwater volume. The average flood peak of backwater is 8 402 m³/s, accounting for 20% of the inflow from Mekong River in the same period. After the flood season, from October to next April, the stored flood of Tonle Sap Lake replenishes to Mekong River, lasting for 244 days on average every year, with a total volume of 71.1 billion m³, which is 1.96 times of the backwater volume from Mekong River and accounts for 29.9% of flood volume of lower Mekong River. Particularly, the replenishing flow from October to next January occupies 83.1% of the total supplementing volume. The interannual variations of duration, volume, and peak discharge of backflow as well as duration, volume, and peak discharge of replenishing flow are stable. The amplitudes reach 76 days, 28.3 billion m³, 6 095 m³/s, and 76 days, 47.4 billion m³ and 4 677 m³/s respectively, with the variation coefficient at 0.07-0.24. The volume of backwater and supplementing water is not only related to the volume of inflow from Mekong River and Tonle Sap Lake, but also affected by the difference of water level between river and lake. The research findings offer scientific evidence for the governance of the Mekong Delta and Tonle Sap Lake Area.