Remote sensing monitoring of the lake area changes in the Qinghai-Tibet Plateau in recent 40 years

Based on RS and GIS technology,remote sensing images including MSS,TM,ETM and topographic maps are visual interpreted to get the areas,positions and changes of the lakes with the area above 10 km2in the Qinghai-Tibet Plateau in 1970s,1990s,2000s and 2010s,respectively. The patterns and trends of lake area changes are analyzed in the respects of regions,area scales and altitude scopes,respectively. Meanwhile,combining with the climate change of the Qinghai-Tibet Plateau during the period of 1972-2011,the main reasons of the lake area changes are discussed. The main conclusions are as follows:( 1) There are 417 lakes with area above 10 km2in the Qinghai-Tibet Plateau. Most of these lakes have an area less than 100 km2and most of them are located in the western region. Seen from the altitude distribution,most of them were concentrated in the range of 4500-5000 m above sea level.( 2) In recent 40 years,the increasing numbers and the areas of these lakes in the Qinghai-Tibet Plateau present an evident expansion pattern,with more evident expanding in the period of 2000s-2010s. As for the regional differences,the changes of these lakes in the eastern and southern regions are slighter than those in the northern and western regions. Small lakes with the area less than 100 km2had larger changes. Lakes with the altitude below 4000 m above sea level had larger changes.( 3) The climate of the Qinghai-Tibet Plateau presented a warmer and more humid tendency in recent 40 years. It is obviously that climate change has a significant influence on lake area changes. According to the analyses,precipitation change seems to be the main reason of lake area changes in the Qinghai-Tibet Plateau.