用稳定同位素方法估算大型浅水湖泊蒸发量——以太湖为例

Estimating evaporation over a large and shallow lake using stable isotopic method: A case study of Lake Taihu

湖泊蒸发量的准确估算对于水文学、气象学和湖泊学等研究有重要的意义.基于2013-2015年太湖水量收支资料、气象观测数据和稳定同位素观测资料,采用稳定同位素质量守恒模型、水量平衡法和Priestley-Taylor模型估算太湖蒸发量,分析太湖蒸发量的季节变化和年际变化特征,并以Priestley-Taylor模型结果为参考值,评价水量平衡法和同位素质量守恒方程的计算精度.结果表明:5-9月太湖蒸发量较高,冬季最低.2013-2015年太湖年总蒸发量分别为1069、894和935 mm,蒸发量的年际变化受到天气条件的影响.2013年12月2014年11月期间,用Priestley-Taylor模型计算的湖泊蒸发量为885 mm;同位素质量守恒模型的估算结果较一致,为893 mm;而水量平衡方程的估算结果明显偏高,为1247 mm.

Accurate estimation on lake evaporation was vital to hydrology, meteorology7 and limnology. Based on the data of water budgets, meteorological and stable isotopic obseiTation over Lake Taihu from 2013 to 2015, the evaporation of Lake Taihu was esti-mated using the isotopic mass balance model, the water mass balance method and the Priestley-Taylor model. The seasonal and in-ter-annual variabilities of lake evaporation were analyzed, and the performance of the water balance method and the stable isotopic water balance model were evaluated with the Priestley-Taylor model result as reference. The results indicated ： Evaporation of Lake Taihu was higher from May to September and less in winter. Annual evaporation in 2013, 2014 and 2015 was 1069, 894 and 935 mm, and the inter-annual variation was controlled by weather condition. Lake evaporation during the period from December 2013 to November 2014 calculated using the Priestley-Taylor model was 885 mm, and the result of the isotopic mass balance model was similar with a value of 893 mm. Whereas it was overestimated significantly by the water balance method with a value of 1247 mm.