Dynamics of Qinghai Lake area based on environmental mitigation satellite data

Remote sensing (RS) and geographic information system (GIS) are essential important means of monitoring water body areas for large lakes and water reservoirs. Based on the characteristics of CCD data from selfdevelopment Environmental Mitigation Satellite and built an identification mode of water body by using the combination methods of multibands and single band. According to the mode, the water area of Qinghai Lake during April-November each year had been extracted from September 2008 to November 2011. The results showed that: 1) The Qinghai Lake area had a continuous increasing trend from 2008 to 2011, among which it had a smaller increase from 2008 to 2010, while there was a significant increase in 2011. 2) From 2009 to 2011, the area of the Qinghai Lake of each season presented a regular wave. However, the area of each season in 2011 was higher than that in the same season of the previous three years. 3) The water area reached to the maximum in every September from 2009 to 2010; and decreased monthly from September to the freeze season in 2008-2010. In 2011, compared to the previous three years, the maximum value emerged in October and the area in each month was significantly larger except the area in July was roughly equal to that in the same period of 2010. 4) The obvious change areas of the Qinghai Lake mainly located in the east and west coasts in October from 2008 to 2011. Shorelines were put into eastward 130-630 m and westward 100-600 m, respectively. The sand island lake in the east coast was seasonally connected to the Qinghai Lake. 5) The major reasons for Qinghai Lake area to increase continually were that in recent years, Qinghai Lake Basin climate showed a warm wet trend, the surrounding river runoff into the lake was increased and human production activities in the surrounding areas were slowed down.