Terrestrial Water Storage Changes in the Tibetan Plateau in the Past Decade and the Possible Cause

Abstract:

Terrestrial water storage (TWS) is the water stored on and below the land surface, which includes snow, ice, soil moisture, groundwater, and surface water. TWS is a fundamental component of the terrestrial hydrological cycle given that precipitation (P) reaching the land surface is balanced by evapotranspiration (ET), runoff (R), and the change of terrestrial water storage (TWSC) [P=R+ET+TWSC]. As an integrated measure of surface and groundwater availability, TWS has significant implications for water resources management. The Tibetan Plateau and its surrounding areas (TP), which are characterized by high elevation, extensive glaciers, permafrost, snowpack, and mountain lakes, is known as the “roof of the world”, the Third Pole, and also the water towers of Asia. Studies of meteorological observations, reanalysis data, and ice core records have suggested a warming trend over the TP in recent decades. Along with the rising temperature, the detected glacier melt, permafrost degradation, and lakes changes in the TP will thus affect the water storage changes and the hydrological cycle in the area. In this study, we examine the spatial-temporal variation of TWS change over the TP through the Gravity Recovery and Climate Experiment (GRACE) satellite data and the VIC land surface hydrologic model during 2004-2013. Meanwhile, the spatial-temporal characteristics of precipitation, evapotranspiration, and snow cover as well as the distribution of glaciers, lakes, and frozen soil are analyzed to examine the factors that might be responsible for the TWS changes in the TP. The objective of our study is to achieve a better understanding of the water balance change in the TP under the warming climate. Our work could provide a basis for conservation strategies and policy decisions for the fragile, invaluable eco-hydrological environment in the Tibet Plateau.