Water Storage Variation Inversion in the Tibetan Plateau by Using Forward-Modeling Method

The water resources in the Tibetan Plateau have a profound impact on China's economic, social development and climate change. Based on gravity data from gravity recovery and climate experiment (GRACE) satellite, considering its filtering leakage error, this paper proposes the Forward-Modeling method for quantitative estimation. In view of the glocial isostatic adjustment(GIA) effect, we first infer terrestrial water storage (TWS) changes in the Tibetan Plateau, and compare the results with the water-global assessment and prognosis hydrology model(WGHM). Then we extract the time-frequency spectrum of time-series signals using short-time Fourier transformation algorithm. In addition, we discuss the relationship between TWS and precipitation by combining with precipitation data from Global Presipitation Climatology Centre. The study finds that:(1) TWS shows obvious spatial differences after recovering leakage signal. In most of the period, TWS in the north and southeast is in large surplus, and TWS in the south and southwest is rapidly depleted. The spatial characteristics are basically consistent with the WGHM results. (2) The time-frequency spectrum distribution of TWS is dominated by low-frequency signals, and time-series dynamic changes have obvious seasonal and periodic changes, with an annual amplitude of 7.5 cm. The increase rate of water storage in 2003-2004 was 3.89 cm/a. The loss rate in 2005-2010 was -0.31 cm/a. The rate of increase in 2011-2014 was 0.22 cm/a. (3) Precipitation is the main factor affecting the variation of TWS. In 2006 and 2009, precipitation was significantly lower, the water storage all decreased significantly. In 2010, there was heavy rainfall, the water storage increased significantly. The leakage error correction method and research results in this paper have important reference value for quantitative research on regional TWS varition.