Study On Tidal Flats In The Bohai Rim Based On Remote Sensing Waterlines

Tidal flats, the sensitive area between marine and terrestrial environment, play an important role in protecting coastal ecosystems and promoting the economic development of coastal regions. In recent years, large-scale sea reclamations have led to great changes for tidal flats, and macroscopic and accurate knowledge of them is urgently required. Based on this, this paper selects the Bohai Rim as the study area whose economy is rapidly developing and studies the more accurate method for extracting the extent of tidal flats using remote sensing and GIS synthetically. Then, comprehensive researches from two aspects, including status and dynamics change, are conducted.The main research contents are listed as follows:(1) This paper uses HJ-1A/B satellite images as the data source. Various waterlines under the different times are analyzed by DSAS software and Jenks Natural Breaks classification method synthetically to determine the extent of tidal flats.(2) Analyze the status and distribution characteristics, and the development degree and the use pattern of tidal flats in the Bohai Rim on 2014.(3) Analyze the dynamic changes and driving forces of tidal flats in modern Yellow River estuary and Caofeidian region from 2009 to 2014.The results prove that: ① In 2014, the stock of tidal flats in the Bohai Rim was 2778.59 km2 and the overwhelming majority of them distributed in the vicinity of river estuaries and bays. ② In 2014, the overall development degree of tidal flats in the Bohai Rim was 1.95 and the overwhelming majority of tidal flats had been developed and utilized. The most common use pattern was aquaculture pond establishing, while the proportion of tidal flats used for agricultural reclamation was the smallest. Undeveloped tidal flats were mainly distributed near bedrock coastlines and sandy coastlines. ③ The change of sediment transportation mode is the main reason for erosion and deposition, and massive sea reclamations could cause the losses of tidal flats and change their distributions.The innovations of this paper are presenting an improved method for mapping tidal flats based on remote sensing waterlines, and analyzing the development degree by introducing tidal flat development degree and use pattern by combining coastline types.To sum up, this paper studies on extraction method, distribution characteristics, development degree, use pattern and dynamic changes of tidal flats, which could enrich research methods and technologies for tidal flats and promote rational utilization and sustainable development of tidal flats.