RS AND GIS ANALYSIS OF ECO-ENVIRONMENTAL CHANGE OF THE NORTHERN WETLAND CONSERVATION AREA IN YELLOW REVIER DELTA

Based on the comparative analysis of the three phases of remote sensing images in 1996,2000 and 2005 respectively,we discussed in this paper the eco-environment changes of the wetland in the northern conservation area of the Yellow River Delta. The boundary between seawater and fresh water reservoir is the control factor of salinity gradient,which plays an important role in the distribution of wetland types. Both the natural factors,such as seawater invasion caused by river channel shifting in 1976 and the storm surge in 1992,and human activities,such as the nurtures of natural tamarisk in 1998 and the expansion of cotton planting afterwards,has rendered big influence on the distribution of wetland types in the area.