Modeling spatial-temporal change of Poyang Lake using multi-temporal Landsat imagery

Abstract

Exchanging water with the lower branch of Yangtze River, Poyang Lake is a seasonal lake. During the spring and summer flooding season it inundates a large area while in the winter it shrinks considerably creating a large tract of marshland for wild migratory birds. A better knowledge on the water coverage duration and the beginning and ending dates for the vast range of marshlands surrounding the lake is important for the measurement, modeling and management of marshland ecosystems. In addition, the abundance of a special type of snail (Oncomelania hupensis) (the intermediate host of parasite schistosome (Schistosoma japonicum) in this region) is also heavily dependent on the water coverage information. However, there is no accurate DEM for the lake bottom and the inundated marshland, nor is there sufficient water level information over this area. In this study, we assess the feasibility on the use of multitemporal Landsat images in mapping the spatial-temporal change of Poyang Lake water body and the temporal process of water inundating of marshlands. All eight Landsat Thematic Mapper images that are cloud free during a period of one year were used in this study. We used NDWI and MNDWI methods to map water bodies. We then examine the annual spatial-temporal change of the Poyang Lake water body. Finally we attempt to obtain the duration of water inundation of marshlands based on the temporal sequence of water extent determined from the Landsat images. The results showed although the images can be used to capture the snapshots of water coverage in this area, they are insufficient to provide accurate estimation on the spatial-temporal process of water inundating over the marshlands through linear interpolation.