Estimation of local water storage change by space- and ground-based gravimetry

• Efficient estimation of local water storage change
• Corrected global part is about one ninth of the total local water storage change.
• Combining space- and ground-based gravimetry gives better information on local water storage change.

We estimated local water storage change by combining space- and ground-based gravimetry in this paper. The gravity change from GRACE was first divided into local and global parts according to potential theory. We then subtracted the GRACE-derived global field from ground gravimeter results to obtain local gravity change which is directly induced by the local water storage. Finally we inferred the local water storage change. We used superconducting gravimeter (SG) data recorded from June 2008 to June 2012 at Wuhan station and GRACE satellite gravimetric data to estimate the local water storage change. To validate the inferred local water storage change, the water table records of a well which is several meters away from SG station were compared. Furthermore, the equivalent water heights from hydrological models and GRACE were used also for comparisons. The comparisons show that the results from combining SG and GRACE data are better than those from either GRACE data alone or hydrological models, which demonstrates the efficiency of the combination method to derive local water storage.