Climatic implications on variations of Qehan Lake in the arid regions of Inner Mongolia during the recent five decades

摘要

The Qehan Lake Basin (QLB) and its system of lakes are located in a marginal monsoon zone and are extremely sensitive to global climate change. In this paper, using aerial photographs from different periods, in addition to MSS, TM, and ETM images, and combining these with regional topographic maps, we analyze lake area changes from 1958 to 2010 and the relation between Qehan Lake (QL) and climate variability. Our results indicate that there was a relatively high lake level in 1959, when the area and volume of the lake were 118.9 km(2) and 151.9 x 10(6) m(3), respectively, but this level was subject to a shrinking trend until 2010, when the lake area was only 28.1 km(2), and the water volume was 41.1 x 10(6) m(3). West Qehan Lake (WQL) has experienced severe water shrinkage and lake level fluctuation. In 1958, WQL was 80.2 km(2) in area and 124.1 x 10(6) m(3) in volume. However, due to a rapid decrease in precipitation and increases in both temperature and evaporation, it began to dry up in 2002. The WQL Water area decreased by 1.82 km(2)/a, and the lake level declined by 7 m during 1958-2002, so it became an ephemeral lake.