The past and future of total water storage changes over the Tibetan Plateau

Abstract:

Total water storage (TWS) over the Tibetan Plateau (TP) is of great significance for fresh water availability, water resources management, and hydrological cycles, which also produces profound influence on large populations living downstream. The TP is among the most sensitive regions responding to climate change. However, the past and future of the changes in the surface, subsurface, and total water storage are not well understood due to the complex hydrologic processes in this high-mountain cryospheric region. Here, we first combined multisource remote sensing (e.g., satellite gravimetry, satellite altimetry, and stereo-imagery data) with land surface models (LSMs) (e.g., Noah, VIC, and CLSM) to analyze changes in surface, subsurface, and total water storage in the past. In addition, we made projections of the future TWS changes during 2021–2050 based on the deep neural network (DNN). Results show that TWS over the Amu Darya, Indus, Ganges, Brahmaputra River basins has a marked decreasing trend (-13 Gt/yr) due to the glacier retreat, whereas TWS over the Tarim and Inner basins has been on the rise (5 Gt/yr) because of the increase in surface water storage during 2002–2017. The future projection suggests challenges in water resources management, particularly over the exorheic basins on the TP which supply large amounts of available water for lower reaches. Our study highlights the response of TWS over the TP to climate change, thereby providing important implications for decision making and public policies for this area and possibly other cryospheric regions as well.