Evolution Rule And Utilization Assessment Of Coastal Wetland In Beijing-Tianjin-Hebei Urban Agglomeration During 1990-2018

Coastal wetlands are rich in natural resources,which are interrelated with the economic society and play a vital role in human survival and development.As the acceleration of urbanization,the development of coastal wetlands is increasing,and there are many ecological problems,especially in the coastal areas such as Hebei Province and Tianjin city,where reclamation is relatively large.In order to make more reasonable use of coastal wetland resources,it is necessary to trace the historical dynamics of these coastal wetlands to explore the management strategy of sustainable utilization of coastal wetlands.Therefore,it is of great significance to analyze the evolution law of Beijing-Tianjin-Hebei urban agglomeration coastal wetland and evaluate the utilization degree of coastal wetland.Taking coastal wetlands in Beijing,Tianjin and Hebei urban agglomerations as research objects,1990,2000,2009 and 2018 remote sensing image Landsat TM and OLI as the data source,combined with the second national land survey results in 2009 and the 2015 national land change survey data.RS and GIS were used to analyze the evolution process of the coastal wetlands in the Beijing-Tianjin-Hebei urban agglomeration,from three aspects of the coastal wetland area,type and coastline,analyzed its evolution law from 1990 to 2018.According to the actual situation of The Beijing-Tianjin-Hebei urban agglomeration coastal wetland,the evaluation index system of its utilization degree was built based on the PSR model,and the utilization degree of the Beijing-Tianjin-Hebei urban agglomeration coastal wetland from 1990 to 2018 was evaluated.The evolution pattern of Beijing-Tianjin-Hebei coastal wetland was analyzed by integrating the evolution law and utilization evaluation results,and taking cities and counties(districts)as research units.Compared with previous studies,the evolution law and utilization degree of coastal wetlands within each administrative area can be clearly demonstrated.In order to provide a scientific theoretical basis for the effective protection and rational development of coastal wetland resources in the Beijing-Tianjin-Hebei urban agglomeration in the future.The research results show that:(1)From 1990 to 2018,both the natural wetland area and the total coastal wetland area in the BeijingTianjin-Hebei urban agglomeration coastal area showed a decreasing trend.The proportion of natural wetland area in the total area of Beijing-Tianjin-Hebei urban agglomeration coastal wetland also decreased step by step,and the constructed wetland area in Beijing-Tianjin-Hebei urban agglomeration coastal area first increased and then decreased,but the proportion of constructed wetland in the total area of Beijing-Tianjin-Hebei urban agglomeration coastal wetland increased gradually.The length of nonwetland shoreline and the total length of coastline showed a trend of continuous growth,while the wetland shoreline showed a trend of slow increase at first and rapid decline later.(2)The expansion from constructed wetland to natural wetland in Beijing-Tianjin-Hebei urban agglomeration coastal area existed in the whole period.The reduction of natural wetlands in the BeijingTianjin-Hebei urban agglomeration coastal area was not only transformed into constructed wetlands,but also transformed into construction land.Especially after 2000,the expansion scale of construction land has been enhanced step by step,and a relatively large scale coastal wetland turned into non-wetland.1990-2000 and 2009-2018 period,construction land to the expansion of the constructed wetland was bigger,our caravan left Changli county were mainly distributed in south area,from 2000 to 2009,construction land to the expansion of the natural wetland was bigger,mainly distributed in Caofeidian District,Tianjin Binhai New Area and Haixing County,Hebei Province.(3)The utilization degree of coastal wetlands in The Beijing-Tianjin-Hebei urban agglomeration presented an increasing trend,and the utilization degree of coastal wetlands in all cities,counties(districts)also presented an increasing trend as a whole.The evolution pattern was mainly constructed wetland expansion from 1990 to 2000,construction land expansion from 2000 to 2018,construction land expansion mainly to the natural wetland from 2000 to 2009,and construction land expansion mainly to the constructed wetland from 2009 to 2018.