Identification of the terrestrial water storage change features in the North China Plain via independent component analysis

Study region: The North China Plain (NCP) is an important agricultural, social, and economic center in China. Significant statistical independence of the hydrological components in NCP exists due to the high variations of natural conditions and human activities both in the horizontal and vertical directions. Study focus: It is critical to understand the features of terrestrial water storage (TWS) changes in NCP. Gravity Recovery and Climate Experiment (GRACE) mission provides valuable measurements for TWS. In this study, the GRACE RL05 mascon data during 2002–2017 in NCP are analyzed via independent component analysis (ICA) and multi-source data to improve the understanding of underlying physical or human-made processes of the regional TWS change New hydrological insights for the region: The relatively independent hydrological components in NCP with GRACE measurements are successfully derived, which characterize annual variation, surface water storage (SWS) change, and the shallow and deep groundwater storage (SGWS and DGWS) changes, respectively. Based on them, it is found that SGWS decreases faster before 2009 and then reduces slower and keeps stable while DGWS decreases faster after 2009, especially after 2012. Further investigation shows that the anthropogenic influences significantly enhance the vertical heterogeneity of water storage changes based on their exploitations of different hydrological components, in which the South-to-North Water Diversion of China changes the water-use mode in NCP, especially for the reduction of the SGWS exploitation.