洞里萨湖的水位和面积变化特征

Variation Characteristics of Water Level and Area of Tonle Sap Lake

洞里萨湖是湄公河最大的连通湖泊,其水位、面积变化对洞里萨湖的结构和功能产生重要影响,辨识水位、面积演变规律对洞里萨湖区与湄公河三角洲防汛抗旱和生态环境保护具有重要指导意义。基于金边港、波雷格丹和甘邦隆站长系列的日均水位数据及湖区地形资料,定量分析了洞里萨湖水位、面积的年际与年内变化特征。结果表明:洞里萨湖水位涨落缓慢,涨水天数少于退水天数,涨水率高于落水率。洞里萨湖年际水位波动频繁,年平均水位、年最高水位、年水位极差值、年洪水历时、年平均洪水位、日涨水率年际变化总体呈小幅下降趋势,年最低水位、退水天数、日落水率年际变化呈上升趋势。洞里萨湖水位、面积年内呈单峰型变化,5月份最低,平均水位1.51 m,相应面积2487 km^2,实测最低水位1.11 m,相应面积2053 km^2;10月份最高,平均水位8.70 m,相应面积12768 km^2,实测最高水位为10.54 m,相应面积15261 km^2,多年平均年内水位变幅7.63 m,面积变幅10628 km^2。研究成果为下一步洞里萨湖区的综合治理规划奠定了基础。

Tonle Sap Lake is the largest lake linked with Mekong River.The variations of water level and area exert vital impact on the structure and function of Tonle Sap Lake.Identifying the evolvement rule of water level and area is of guiding significance for flood control and drought relief as well as eco-environmental protection in Tonle Sap Lake and the Mekong Delta.According to long series of daily water level data of Phnom Penh Port,Prek Kdam and Kampong Luong stations and topographic data of lake area,we analyzed the inter-annual and annual variations of water level and area of Tonle Sap Lake.Results reveal that the water level of Tonle Sap Lake raise and fell slowly,with the rising duration shorter than falling duration and rising rate higher than falling rate.The water level of Tonle Sap Lake fluctuated frequently between years,with the annual average water level,annual maximum water level,annual water level range,annual flood duration,annual average flood level and daily rising rate all showing slight downward trend,while the annual lowest water level,water withdrawal days and daily falling rate showing upward trend.The annual water level and area of Tonle Sap Lake changed with a single peak value.The lowest water level was in May,when the average water level was 1.51 m and the corresponding area 2487 km^2,the measured minimum water level 1.11 m and the corresponding area 2053 km^2;the water level reached the maximum value in October,when the average water level was 8.70 m and the corresponding area 12768 km^2,the measured maximum water level 10.54 m and the corresponding area 15261 km^2.Multi-year average water level range of Tonle Sap Lake was 7.63 m and the corresponding area range was 10628 km^2.