Abstract:

Intertidal elevation acquisition is the fundamental work in understanding the intertidal sedimentation/ erosion trend and reasonably developing intertidal resources.To counter the problem of high cost and effort to measure the intertidal elevation on the spot，this paper reports the development of an elevation acquisition method based on multitemporal remote sensing images.The method mainly consists of three steps，i.e.remote sensing images selection，waterline extraction and waterpoint elevation calculation.Usually，the waterline is assumed as a contour.But Jiuduansha intertidal mudflat is so wide that the waterline is not horizontal completely and shouldn’t be assumed simply as a contour.In this paper，three groups of waterlines are extracted from three Landsat TM images acquired under different tidal conditions in 2004.Taking all vertexes of one waterline group as a group of waterpoints，the authors calculate their elevations by using a simple trend surface interpolation based on the instantaneous tide levels of four tide stations around Jiuduansha.These waterpoint elevations are compared with the in situ measurement elevations.It is revealed that the average absolute error of the waterpoint elevations is about 0.138 m，and the precision is about 93.74%.

Key words: remote sensing, waterpoint, tide level, Jiuduansha intertidal mudflat, digital elevation model