Remote sensing retrieval of water storage changes and underlying climatic mechanisms over the Tibetan Plateau during 2000—2020

Climate change has profound impacts on water storage over the Tibetan Plateau (TP). This may seriously threaten freshwater availability, disaster prevention, and ecological integrity for about 1 billion people living downstream. Here we integrate multisource remote sensing (including satellite gravity, satellite altimetry, and optical images) and related algorithms that were developed mostly by the authors to estimate changes in various water storage components over the TP during 2000—2020. Estimated water storage includes lake and glacier storage, snow depth and snow water equivalent, and total water storages (TWS). In addition, we examine underlying climatic mechanisms for these storage changes. Results show that : ① TWS shows a significant decrease (-10.90 Gt/a) for exorheic TP basins dominated by glacier retreat, but a marked increase (6.40 Gt/a) in endorheic basins reflected mostly by lake expansion in recent decades (2002—2020).② Lake storage over the TP shows an increasing trend during 2002—2020, and this trend can be divided into a stable growth period (2002—2012, 6.35 Gt/a), a relatively stable period (2012—2017, 1.42 Gt/a), and a rapid growth period (2017—2020, 10.59 Gt/a). Lake water storage changes show high consistency with precipitation variations. ③ Glacier mass over the Southeastern TP declined rapidly during 2002—2019 (-4.50 Gt/a). Rising temperatures and interannual variability in precipitation are the dominate climate factors that resulted in glacier retreat over this region. ④ Annual average SWE during 2016—2020 shows an increasing trend compared to that during 2001—2015. Changes in SWE are affected mostly by average temperature and precipitation during the snow accumulation periods.