Differences and cause analysis of changes in lakes of different supply types in the north-western Tibetan Plateau

Most lakes of the Tibetan Plateau were experiencing quick expansion in recent decades; a detailed study on the changes in lakes of different supply types will help to understand the cause of the changes by analysing area change of 34 lakes and water level change of eight lakes in the north-western Tibetan Plateau. All lakes are classified into three types: non-glacier-fed lakes, upstream lakes and glacier-fed lakes. The glacier-fed lakes are separated into glacier-fed_P1 (quick expansion region) and glacier-fed_P2 (slow expansion region). Combining the changes in precipitation, temperature and evaporation, less precipitation may be the main reason for lake shrinkage from 1976 to 1996 and quickly increasing precipitation led to the lakes' expansion from 1996 to 2000. However, after 2000, upstream lakes remained in a stable state with slight variation, non-glacier-fed lakes and glacier-fed_P2 lakes exhibited a slightly increasing rate with high precipitation and high evaporation, and glacier-fed_P1 lakes still expanded quickly. On the basis of the assumption of same precipitation and evaporation, glacial meltwater may make an important contribution (>52%) to the increase in water storage of Bangdag Co and Meima Co. The results suggest that glacial meltwater augments the increased rate of glacier-fed_P2 lakes and plays a much more important role in the expansion of glacier-fed_P1 lakes compared to other lakes.