近20年青海湖水量变化遥感分析

Water storage variation of the Qinghai Lake in recent decades based on satellite observation

青藏高原湖泊水量的变化是揭示全球气候变化及其区域水循环响应的重要信息载体。区别于常用的水文学方法,本文利用MODIS遥感影像和LEGOS高度计多年连续数据,基于湖泊水位—面积关系,探讨了湖泊水量变化的遥感分析方法,并以青藏高原面积最大的青海湖为例,揭示青海湖近20年来(2001-2016)湖泊水量年内与年际变化特征。主要结论为:青海湖湖泊面积在2001-2016年间整体扩张了187.9 km^2,变化速率为11.6 km^2/a;水位在2001-2014年间上升了1.15 m,变化速率为0.10 m/a。青海湖水位—面积关系表现为二次函数关系(相关系数R^2=0.83)。基于水位—面积关系,进一步估算分析了青海湖水量平衡的净收支及其年内和年际变化。近20年来,青海湖水量总体呈增加趋势,其变化率约为4.5×10~8m^3/a。降水的增加与蒸发能力的下降是湖泊水量增加决定性的驱动因子。

Changes in water storage of the lakes on the Tibetan Plateau are regarded as one of the most critical consequences of regional hydrological response to climate change. Different from the conventional hydrological approaches, in this study we investigated the storage change of the Qinghai Lake based on a conceptual lake storage model and the most recent（2001-2016） available satellite observation on lake area and water level. The water surface areas and water levels were derived from MODIS and LEGOS altimetry data respectively. The results show that, in the past decades, the area of the Qinghai Lake expanded at a rate of 11.6 km-2/a and the water level rose at the speed of 0.10 m/a. Based on the regression function between water level and lake area（R-2=0.83）, the net water budgets of the Qinghai Lake were estimated for the study period, and the result shows that water storage of the lake increased at the rate of about 4.5 billion m-3/a. The increase of water storage could be attributed to the increase of precipitation and decrease of evaporation in the region.