基于长时序Landsat 5/8多波段遥感影像的青海湖面积变化研究

Study on the Area Variation of Qinghai Lake Based on Long-Term Landsat 5/8 Multi-Band Remote Sensing Imagery

青海湖作为高海拔的内陆湖泊,其表面水体面积多年变化对寒旱区的气候变化和水循环至关重要。为了研究30年来青海湖湖泊面积变化规律,提取了1986—2017年(除去2012年)覆盖青海湖的459景Landsat5/8影像,采用6种常用的水体提取方法分别提取了青海湖表面水体面积,并分析了不同方法的差异,最终分别对Landsat 5 TM和Landsat 8 OLI遥感影像采用改进的归一化差异水体指数(MNDWI)和水体指数2015(WI2015)方法获得1986—2017年青海湖表面水体面积的年变化,并分析其变化趋势。结果表明:1989—2003年青海湖面积减小了175.34km^2,年平均减小率为12.52km^2/a,2003—2017年青海湖面积增加了183.43km^2,年平均增加率为13.10km^2/a,整体上,1986—2017年青海湖面积增加了104.46km^2,年平均增加率为3.37km^2/a。

As a high-altitude inland lake,Qinghai Lake's annual change in surface water area is critical for climate change and water cycle in the cold and arid regions. In order to study the spatial and temporal variation of area of Qinghai Lake in the past 30 years,extract 459 images from Landsat 5/8 that covering Qinghai Lake from 1986 to 2017(excluding 2012). Apply six common water extraction methods to extract the surface water area of Qinghai Lake and analyze the differences of methods. Finally,obtain the annual surface water area variation of Qinghai Lake from 1986 to 2017 by using MNDWI and WI2015 water extraction methods for Landsat5 TM and Landsat8 OLI images respectively,and analyze its variation trend. The results show that the area of Qinghai Lake decreased by 175.34 km^2 from 1989 to 2003,and the average annual reduction rate was 12.52 km^2/a . The area of Qinghai Lake increased by 183.43 km^2 from 2003 to 2017,and the average annual increase rate was 13.10 km^2/a. The area of Qinghai Lake increased by 104.46 km^2,and the average annual increase rate was 3.37 km^2/a from 1986 to 2017.