Abstract:

The shorelines of tidal flat in an estuary，located in the intersection zone of river and sea and influenced by runoff water together with sediments from upstream，wave and current，tidal dynamics and human activities，vary continuously in time and space.In overcoming some shortcomings existing in visual interpretation of shoreline from remote sensing images，this article elaborates an objectoriented shoreline automatic extraction method.Taking east tidal flat region of Chongming Island (Dongtan) as an experimental area，four scenes of TM/ETM+ images acquired respectively on Dec 4 1990，April 4 1995，June 14 2000 and Nov 27 2005 covering Chongmin Dongtan are processed based on the objectoriented method.The shorelines and polygons representing the tidal flat above shorelines are extracted for each year.The overlay analysis is applied to observe the spatial variation of erosion and accretion of Chongming Dongtan from 1990 to 2005.The application results prove that the objectoriented remote sensing image recognition method for shorelines and tidal flat erosion and accretion analysis is quick，easy to use and effective.

Key words: objectoriented classification, accretion and erosion analysis, TM image, shoreline, tidal flat〖