The Change Of Inundation Frequency In Poyang Lake And The Response Of Its Wetland Vegetation Which Base On Pixels Decomposition Model In MODIS

In the lake ecosystem,the change of hydrological characteristics significantly promote the formation and change of wetland vegetation,and then affect the quality of fish,wildlife habitats and even the entire lake ecosystem.In recent years,remote sensing technology is widely used for the extraction and change monitoring of lake,for its wide range of monitoring,high synchronism,short cycle and low cost.Lake Poyang,as a typical fresh lake with shallow water,is the largest lake in the lower reaches of the Yangtze River.The lake area of Lake Poyang changes seasonally,in response to the regional climate and human intervenes.Therefore,it is important to monitor the temporal dynamics of the water body area of Lake Poyang.In this study,we obtained MODIS satellite data from 2000 to 2015 AD,trying to reveal the temporal dynamics of Lake Poyang and its potential influences on the developments of vegetation.The main contents include the following aspects:(1)The area of water body are extracted with the Pixels Spectral decomposition model.We find that the Pixels Spectral decomposition model shows great stability and accuracy in the water body extraction,with an accuracy assessment of 97.45%.And when Compared with the index model,the Pixels Spectral decomposition model is less influenced by light clouds,and performs better in the extraction of landscape details.(2)The spatial distribution of Inundation Frequency in the receding period shows a decreasing trend from the north to the south.The north area,especially the channels into the Yangtze River,has relatively high Inundation Frequency.In the middle-south area,Inundation Frequency relates closely to the topography of the lake,with the higher lands having lower Inundation Frequency.In general,the spatial distribution of Inundation Frequency demonstrates the evolution of Lake Poyang,and is also related to the lake topography.Different area in Lake Poyang also shows different temporal trends of Inundation Frequency.In the north area,the Inundation Frequency in the receding period decreased rapidly from 2000 to 2010 AD,and then recovered to the stable condition during 2010-2015 AD.On the other hand,in most area in the middle lake,the Inundation Frequency shows a gentler,but still visible,decreasing trend,while the Inundation Frequency in the south lakes does not change greatly in the last 15 years.Generally,the temporal changes of the Inundation Frequency in Lake Poyang highlight the impact from human intervenes in different area.(3)Integrated with the changes of vegetation abundance,we further discuss the influences of Inundation Frequency on the vegetation development.The vegetation abundance reaches the maximum when Inundation Frequency equals with 40%.This means that the vegetation develops best in area with an Inundation Frequency of 40%.