MODELING THE IMPACTS OF LAND USE/COVER CHANGE ON SEDIMENT LOAD IN WETLANDS OF THE POYANG LAKE BASIN

Abstract

Poyang Lake watershed mainly consists of Poyang Lake and its five sub-watersheds. Its wetlands, the largest bird habitat in Asia, play an important role in biodiversity and ecologic protection. With the rapid economic growth and urbanization, the wetlands in Poyang Lake area have been shrinking and face many environmental challenges. To better understand the environmental and ecologic changes of wetlands in the Poyang Lake watersheds, we applied RS/GIS techniques and a mathematical model in a study of the relationship between land use/cover changes and sediment load of the Poyang Lake watershed. RS classification was used to detect the land use/ cover change, and a relational searching algorithm of spatial objects was proposed to improve the classification accuracy of wetlands. The driving forces for the land use/cover change were also analyzed. Soil erosion by water, as a big environmental problem, reflects the process of surface water related to non - point source pollution that influences water quality, the environment, and ecology of wetlands. In this study GIS and RS technologies are employed to predict annual soil loss. This work prioritizes erosion-prone areas which are important sources of sediment and highlights the severity of soil erosion in the watershed. SSC (suspended sediment concentration) data were collected for the study period. The relationships among land use/cover change, erosion area variations and SSC alterations are examined for the study period. The results show that the land use/cover change in the watershed lessen sediment sources and led to less SSC load to the wetland. The Poyang Lake is less impacted by the SSC in 2000 compared with 1991.