联合GRACE和GPS解译加州地下水储量变化

Retrieve groundwater storage variation in California using GRACE and GPS

本文基于2002年04月—2016年08月共156月的GRACE时变重力场模型与地表水文模型,采用组合滤波与尺度因子法获取加州地下水储量变化,并联合EMD分解后的GPS测站垂向时间序列进行分析.结果显示:基于Swenson去相关与250 km高斯平滑半径组合滤波的GRACE地下水反演结果和GPS垂向时间序列季节性变化结果较好,与降水资料季节性变化特征明显,2002—2016年年均等效水高变化-9.4±2.1 mm/a.GPS测站垂向时间序列与附近水井相关性较好.通过深入分析发现地下水亏损是造成地表沉降的主要原因,且降水能够有效缓解以农业灌溉为主的地下水抽取.

We computed groundwater storage variation using GRACE time-variable gravity field. Affected by satellites orbit characteristics and measurement errors, the inversion results obtained from original GRACE data are presented with serious stripes errors. This paper uses de-correlated filtering and Gaussian filtering on destripe. Considering the filtering leakage error, this study proposes the Scale-Factor method by GLDAS. In this paper, we decompose the GPS time series by EMD and extract the trend, and the results agree with the groundwater by GRACE inverse during the same period. The inversion results show the same obvious seasonal characteristics as is found in precipitation. GPS height time series have a strong correlation with the precipitation and the correlation coefficient between them is 0.96. Groundwater depletion is the main factor affecting vertical surface displacement and precipitation can relieve the groundwater depletion caused by agricultural irrigation.