Lake level changes determined by Cryosat-2 altimetry data and water-induced loading deformation around Lake Qinghai

Abstract

Lake Qinghai mass variation can cause local crustal deformation and lake level is sensitive to the change of regional climate. Hence, in order to explore the possibility of the Global Positioning System (GPS) technology to monitor the water-induced crustal deformation, we use the Cryosat-2/SIRAL altimeter data to investigate the variations of Lake Qinghai level and its impacts on local crustal deformation from July 1, 2010 to December 31, 2018. We apply the load Green's function method to model the loading deformation field around the Lake Qinghai region and compared it with GPS measurements. The results show that the Cryosat-2/SIRAL altimeter can effectively monitor the water level changes of Lake Qinghai, and the lake water level rises at a rate of 0.19 m/yr and exhibits obvious seasonality. The vertical deformation is more sensitive to changes in water level than the horizontal deformation. The apparent loading displacements induced by lake level change are mainly distributed within 25 km of the boundary of Lake Qinghai, with the horizontal and vertical displacements exceeding 1 and −3 mm, respectively. Furthermore, the accumulative vertical and horizontal displacements of −7 and 2 mm are found at the boundary of Lake Qinghai during the period from July 1, 2010 to December 31, 2018 and the detected linear trend of displacements are about −0.70 mm/yr and 0.15 mm/yr, respectively. The modeled loading displacements and GPS measurements at QHGC station have good trend consistency in the vertical component, but the amplitude consistency and correlation coefficient are not satisfactory, which may be caused by the resolution of GPS data, the uncertainty of modeled loading displacement and the remote geographical location of QHGC station. The feasibility to monitor the local crustal deformation caused by Lake Qinghai level change with geodetic techniques such as Global Navigation Satellite System (GNSS) still needs further study.