North China Plain Water Storage Variation Analysis Based on GRACE and Seasonal Influence Considering

Based on the remove-restore method, the GRACE satellite gravity data are used to study the variation of terrestrial water storage from January 2003 to June 2014 in North China Plain. A method for calculating the scale factor considered seasonal influence is proposed to reduce the GRACE post-processing error. The results obtained by the proposed method are compared with those from hydrological model and the precipitation model. The results indicate that serious drought occurred in North China Plain before 2008, and the terrestrial water and surface water decrease at the rate of (-7.9±2.4)mm/a and (-7.3±2.8)mm/a respectively while the groundwater decrease only at the rate of (-0.6±1.4)mm/a. However since 2008, the terrestrial water and surface water show an upward trend of (4.3±1.3)mm/a and (10.9±2.1)mm/a respectively.On the other hand, the over-exploitation of groundwater began to aggravate, and groundwater level showed a downward trend of (-6.5±1.2)mm/a, but the descent rate was reduced at the rate of -0.9 mm/a2.During the study period, the terrestrial water, surface water and groundwater storage in North China Plain show a trend of (-2.0±0.6)mm/a, (2.9±0.7)mm/a and (-4.8±0.7)mm/a respectively.Finally, the phenomenon of GRACE lagging behind precipitation is analyzed using cross-wavelet spectrum.Research revealed that the two most crucial factors influencing the water storage variation in North China Plain are precipitation and groundwater exploitation