Groundwater storage changes in the Tibetan Plateau and adjacent areas revealed from GRACE satellite gravity data

• Published in: Earth and Planetary Science Letters
• Main Authors: Xiang, L, Wang, HS, Steffen, H, Wu, PPC, Jia, L, Jiang, L, Shen, Q
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Ice; permafrost
• Online Access: https://doi.org/10.1016/j.epsl.2016.06.002; http://hdl.handle.net/10722/227222

Understanding groundwater storage (GWS) changes is vital to the utilization and control of water resources in the Tibetan Plateau. However, well level observations are rare in this big area, and reliable hydrology models including GWS are not available. We use hydro-geodesy to quantitate GWS changes in the Tibetan Plateau and surroundings from 2003 to 2009 using a combined analysis of satellite gravity and satellite altimetry data, hydrology models as well as a model of glacial isostatic adjustment (GIA). Release-5 GRACE gravity data are jointly used in a mascon fitting method to estimate the terrestrial water storage (TWS) changes during the period, from which the hydrology contributions and the GIA effects are effectively deducted to give the estimates of GWS changes for 12 selected regions of interest. The hydrology contributions are carefully calculated from glaciers and lakes by ICESat-1 satellite altimetry data, permafrost degradation by an Active-Layer Depth (ALD) model, soil moisture and snow water equivalent by multiple hydrology models, and the GIA effects are calculated with the new ICE-6G_C (VM5a) model. Taking into account the measurement errors and the variability of the models, the uncertainties are rigorously estimated for the TWS changes, the hydrology contributions (including GWS changes) and the GIA effect. For the first time, we show explicitly separated GWS changes in the Tibetan Plateau and adjacent areas except for those to the south of the Himalayas. We find increasing trend rates for eight basins: +2.46 ±2.24Gt/yrfor the Jinsha River basin, +1.77 ±2.09Gt/yrfor the Nujiang-Lancangjiang Rivers Source Region, +1.86 ±1.69Gt/yrfor the Yangtze River Source Region, +1.14 ±1.39Gt/yrfor the Yellow River Source Region, +1.52 ±0.95Gt/yrfor the Qaidam basin, +1.66 ±1.52Gt/yrfor the central Qiangtang Nature Reserve, +5.37 ±2.17Gt/yrfor the Upper Indus basin and +2.77 ±0.99Gt/yrfor the Aksu River basin. All these increasing trends are most likely caused by increased runoff recharges from melt water ...