Water Level Variation in Qinghai Lake from Global Ecosystem Dynamics Investigation (GEDI) Altimetry Data

Abstract

Qinghai Lake is the largest inland lake in China. It is an ideal place to study climate response, water balance and hydrological process. The Global Ecosystem Dynamics Investigation (GEDI) mission, launched on December 5th, 2018, provides an opportunity for monitoring middle and low latitude water body changes. In this paper, variations of Qinghai Lake water level change are extracted from GEDI L2A data and validated by the latest date or same day acquired by ICESat-2/ATL13 lake water level during April 2019 to April 2020. The results show that the average annual water level of Qinghai Lake is 3152.72± 0.71m. lake water level is lower in April and May, subsequently gradually increased, and reached the maximum in August, and then began to decline in September and October. Comparing with ICESat-2, the water surface heights obtained by GEDI are 0.25 m± 0.38m than that of ICESat-2 after excluding large outliers. For individual beams, the water levels obtained by the coverage beams are higher about 0.14m than that of full power beams. The validation turns out that the GEDI has high accuracy in monitoring water surface level and is of great significance to make up for the lack of hydrological stations or difficult to measure lakes dynamic change over the mountainous areas, as well as global climate change.