Heterogeneous change patterns of water level for inland lakes in High Mountain Asia derived from multi-mission satellite altimetry

Abstract

High-altitude inland lakes in High Mountain Asia (HMA) are key indicators to climate change and variability as a result of mostly closed watersheds and minimal disturbance by human activities. However, examination of the spatial and temporal pattern of lake changes, especially for water-level variations, is usually limited by poor accessibility of most lakes. Recently, satellite altimeters have demonstrated their potential to monitor water level changes of terrestrial water bodies including lakes and rivers. By combining multiple satellite altimetry data provided by the Laboratoire d'Etudes en Géophysique et Océanographie Spatiales (LEGOS) and Geoscience Laser Altimeter System (GLAS) instrument on the NASA Ice, Cloud and land Elevation satellite (ICESat), this study examined water level changes of typical lakes in HMA at a longer timescale (in the 1990s and 2000s) compared with earlier studies on Tibetan lakes. Cross-evaluation of the radar altimetry data from LEGOS and laser altimetry data from ICESat/GLAS shows that they were in good agreement in depicting inter-annual, seasonal and abrupt changes of lake level. The long-term altimetry measurements reveal that water-level changes of the 18 lakes showed remarkable spatial and temporal patterns that were characterized by different trends, onsets of rapid rises and magnitudes of inter-annual variations for different lakes. During the study period, lakes in the central and northern HMA (15 lakes) showed a general growth tendency, while lakes in South Tibet (three lakes) showed significant shrinking tendency. Lakes in Central Tibet experienced rapid and stable water-level rises around mid-1990s followed by slowing growth rates after 2006. In contrast, the water-level rises of lakes in the northern and north-eastern Tibetan Plateau were characterized by abrupt increases in specific years rather than gradual growth. Meteorological data based on station observations indicate that the annual changes of water level showed strongly correlated with precipitation and evaporation but may not evidently related to the glacier melting induced by global warming.