咸海流域陆地水储量时空变化研究

Spatiotemporal variation of terrestrial water storage in Aral Sea Basin

采用2002—2016年GRACE(Gravity recovery and climate experiment)重力卫星JPL-RL06M数据分析咸海流域陆地水储量变化(Terrestrial water storage change,TWSC)时空变化特征,并结合CRU TS4.03气象数据、GLDAS-Noah地表蒸散发数据和高精度土地利用数据探究气候变化与人类活动对陆地水储量的影响。结果表明:(1)2002—2016年咸海流域陆地水储量变化呈现-3.20 mm·a^(-1)下降趋势,春、夏季陆地水储量呈盈余态势,秋、冬季呈现亏损状态;水储量变化在空间上表现为中部和东部盈余,周边亏损的特征。(2)2002—2016年咸海流域降水量呈-1.14 mm·a^(-1)下降趋势,地表温度呈0.11℃·a^(-1)上升趋势;相比气温,水储量变化与降水量相关性更强。(3)2000—2015年,咸海流域耕地面积小幅增加1.65×10^(4) km^(2),水域面积减少;农作物耗水和灌溉需水的增加加剧了咸海流域水量支出,咸海流域蒸散发呈21.63×10^(8) m^(3)·a^(-1)增加态势,在空间上与陆地水储量变化的相关系数最高达0.74,是影响陆地水储量变化的主要因素之一。

The Aral Sea,which was once the largest inland lake in Central Asia,is located far from oceans,and thus,a vulnerable hydrological system.The water balance in the lake has changed in recent decades under the combined impacts of climate change and anthropological activities,and problems related to limited water resources and ecological environment have attracted wide attention.Analysis of the variation trend and influencing factors of terrestrial water storage(TWS),one of the most important parameters of land water variation,can provide a scientific basis for the sustainable utilization of water resources in the Aral Sea Basin.In this paper,the spatiotemporal variations of terrestrial water storage change(TWSC)in the Aral Sea Basin are evaluated using the JPL-RL06M data collected by the GRACE gravity satellite from 2002 to 2016.CRU TS4.03 meteorological data,GLDAS-Noah surface evapotranspiration data,and high-precision land use data are combined to assess time-series changes in TWSC,precipitation,temperature,and water evaporation via the linear trend method.Using a resolution of 1°×1°pixel,we calculated the correlation coefficients of various parameters,including TWSC,precipitation,and surface temperature,to explore the effects of climate change and anthropological activities on TWS in the Aral Sea Basin.Several interesting results were obtained.(1)The TWS of the Aral Sea Basin declined at a rate of −3.20 mm·a^(−1) in 2002—2016.A water surplus in spring and summer and a water deficit in autumn and winter were observed.Moreover,the TWSC of the Aral Sea Basin was characterized by a surplus in the central and eastern regions and deficits in peripheral areas.(2)Precipitation in the Aral Sea Basin in 2002—2016 decreased at a rate of −1.14 mm·a^(−1),and the surface temperature increased at a rate of 0.11℃·a^(−1).Precipitation and TWSC were positively correlated in most areas of the Aral Sea Basin but negatively correlated in the middle and lower reaches of the Amu Darya Basin and the lower reaches of the Syr Darya Basin.The surface temperature was negatively correlated with TWSC in most areas,but a positive correlation between these parameters was observed in some areas in the lower reaches of the Amu Darya and Syr Darya River Basins.TWSC was more strongly correlated with precipitation than with surface temperature.(3)In 2000—2015,the cultivated land area in the Aral Sea Basin increased slightly by 1.65×10^(4) km^(2),but the grassland and water areas decreased.Increases in water for crop management and irrigation intensified water expenditures from the Aral Sea Basin.Under the joint influence of climate change and anthropological activities,evapotranspiration in the Aral Sea Basin increased at a rate of 21.63×10^(8) m^(3)·a^(−1).The correlation coefficient between evapotranspiration and TWSC was as high as 0.74,which means this parameter may be a main factor affecting TWSC.