Water storage redistribution over East China, between 2003 and 2015, driven by intra- and inter-annual climate variability

Qing He (1) , Kwok Pan Chun (1) , Hok Sum Fok (2) , Qiang Chen (3) , Bastien Dieppois (4) , Nicolas Massei (5)

1 HKBU - Hong Kong Baptist University
2 Wuhan University [China]
3 NUS - National University of Singapore
4 CAWR - Centre for Agroecology, Water and Resilience
5 M2C - Morphodynamique Continentale et Côtière

National development and resilience are strained by shifting regional water storage patterns. The water shifting pattern has been found over China, but the underlying climate mechanisms of the pattern remain largely unexplored. In this study, how shifting regional moisture conditions are related to intra-annual and inter-annual atmospheric oscillations can be explored by terrestrial water storage (TWS) derived from the Gravity Recovery and Climate Experiment (GRACE). Using a principal component analysis (PCA), the TWSs over the East China were divided into two spatial empirical orthogonal functions (EOFs), accounting for more than 70% of the total spatial variance. The first TWS EOF is related to the seasonal variation, whereas the second TWS EOF is associated with the spatial distribution of TWS trend. In addition, the PCA trend results for precipitation and actual evapotranspiration (ET) are consistent with TWS, with a correlation of 0.44 (p ≪ 0.05) and −0.47 (p ≪ 0.05), respectively. Based on these PCA results, the Yangtze River Basin (YARB) was wetting, while the North China Plain (NCP) was drying between 2003 and 2015. This unbalance water distribution pattern was potentially linked to regional changes of the Hadley-type meridional circulation which aggravated the unevenness between north and south water distributions over the East China. Furthermore, a wavelet transform coherence (WTC) analysis was used for investigating multi-scale relationships between TWS and different climate factors. The local wind intensity and Asian monsoons were related to the regional unbalance TWS pattern on an intra-annual scale, with significance correlations of −0.49 (at p ≪ 0.05) and 0.9 (at p ≪ 0.05) respectively. Meanwhile El Nino Southern Oscillations (ENSO) was significantly negatively linked (correlation of −0.41, p ≪ 0.05) with TWS variability at the inter-annual scale. However, based on partial WTC results, the association between ENSO and TWS can be explained away by the Asian monsoons, so that ENSO is only indirectly related to TWS through monsoons. Overall, the approaches and results of this study not only explained that the shifting TWS distribution over the East China was related to varying strength of local wind intensity and Asian monsoons, and ENSO at intra-annual and inter-annual scales respectively, but also provided a framework for studying TWS redistribution over other regions, which are crucial for sustainable regional development and resilient water future

Domaines: Hydrologie; Climatologie

Qing He, Kwok Pan Chun, Hok Sum Fok, Qiang Chen, Bastien Dieppois, et al.. Water storage redistribution over East China, between 2003 and 2015, driven by intra- and inter-annual climate variability. Journal of Hydrology, 2020, 583, pp.124475. ⟨10.1016/j.jhydrol.2019.124475⟩. ⟨hal-02886407⟩