利用GRACE重力卫星数据反演黑河流域地下水变化

Changes of Groundwater Storage in the Heihe River Basin Derived from GRACE Gravity Satellite Data

干旱区地表水资源有限,地下水资源被超采利用,黑河流域是西北干旱区典型内陆河流域,有同样的地下水资源利用问题.然而由于监测地下水变化的测井数目有限且分布不均,难以从流域尺度上把握地下水资源的时空变化.利用GRACE重力测量卫星数据反演黑河流域2003—2008年间的地下水时空变化,为合理分配利用水资源提供科学依据,为掌握无资料区域地下水水资源及其变化趋势提供了计算方法.为验证GRACE反演结果的可靠性,首先将计算出的黑河中上游地下水的变化,与该区域实测地下水变化数据进行对比分析,结果显示二者之间相关性较好,在一定程度上表明GRACE数据具备反演整个黑河流域水储量变化及其各个组分的能力.此后,利用GRACE数据反演了全黑河流域的地下水变化,对其时空变化进行了分析和讨论.结果表明:黑河流域2003—2004年间地下水减少的幅度越来越少,2005年夏季期间地下水资源量增加量最多,自此地下水增加幅度逐渐减少,至2008年趋于平衡.空间上流域局部变化波动较大,2003—2004年间黑河上游地下水资源量处于减少状态,2005年相对于6a地下水平均含量有轻微增加趋势,2006年处于6a平均值状态,2007—2008年有稍微上升趋势;中游在2005年有略微的上升,之后3a下降;下游地下水含量在6a中整体呈上升趋势.

Water scarcity is becoming an increasingly severe problem in arid and semiarid regions because of limitation of available surface water resources and over exploitation of groundwater.As a typical inland river basin in the arid and semiarid regions of Northwest China,the Heihe River basin is facing the same trouble of water resources.Because there is limited and unevenly distributed groundwater monitoring wells within the basin,monitoring groundwater change is hard.In this paper,it is intended to derive temporal and spatial groundwater variation in the Heihe River basin for the period of 2003—2008 from GRACE recovery satellite data,which will be useful for better understanding groundwater resources changing characteristics in the basin.The study also offers a feasible approach to monitor groundwater variation of a river basin only with a small number of（or even without site） groundwater data.To verify the approach,only the groundwater data in the upper and middle reaches of the river was used.The correlation between the derived groundwater variation and the measured one is relatively high,which consequently shows the applicability of GRACE in the river basin to some extent.Based upon preliminary verifications,the method is applied to the entire Heihe River basin.It is found that the groundwater amount decreased,with a small magnitude,in the entire basin during 2003—2004.In 2005 summer groundwater increasing reached a highest rate,and then the increasing magnitude began to decrease,and no more increase in 2008.Spatially,in the upper reaches of the river,groundwater showed decline in 2003—2004,with a slight increase in 2005,no increase in 2006 and a small increase in 2007—2008.In the middle reaches of the river,groundwater slightly increased in 2005,and then declined in the following three years.In the lower reaches of the river,groundwater kept increase in the total 6 study years.