A monitoring study on tidal-flat structures in the Inner Lingding Sea for Pearl River Estuary during 1988-2021
[Objective]To reveal the extent and geomorphologic structure of the tidal-flat under the influence of cyclic tide level in coastal cities,[Methods]based on the GEE platform,we collected Landsat image data,and constructed a 3 a tidal-flat structure dataset of the Inner Lingding Sea in the Pearl River Estuary from 1988 to 2021 by means of the tidal imagery fusion algorithm to analyze the structure of the beach and its spatio-temporal evolutions in conjunction with the Coastal Zone Project.[Results]The result showed that,a total of 33.7 km2 of tidal-flat were found in Inner Lingding Sea(including the northern part of Shenzhen Bay),mainly distributed in the northern part of Shenzhen Bay,Longdan Island,and the coastal zone from Jiaomen to Hengmen,with the proportion of the Shenzhen section accounting for 42％,that of the Zhongshan section accounting for 25％,and that of the Guangzhou section and the Dongguan section being narrow in area.Inner Lingding Sea tidal-flat as a whole showed a flucting downward trend of tidal-flat,and the frequency of occurrence gradually reduced,12 period of the total area of tidal-flat cumula-tive reduction of 65.39 km2,the supratidal zone from 15.67 km2 reduced to 4.25 km2,the intertidal zone of 37.32 km2 reduced to 5.44 km2,the subtidal zone of 46.14 km2 reduced to 24.04 km2,the overall intertidal zone of the mudflats and the supratidal zone Overall,the intertidal and supratidal zones of the mudflat had the largest reduction in area.[Conclusion]The dynamic tran-sitions of the supratidal and intertidal zones can be effectively recognized by long time-series images.The expansion of reclama-tion projects has result ed in the permanent occupation of the whole tidal-flat,while the ecological restoration projects have effec-tively maintained the area and distribution of partial tidal-flat.
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