Temporal And Spatial Dynamic Evolution Of Coastal Wetland Under The Action Of Sea Reclamation In Bohai Rim During 1980-2017

Coastal wetlands are unique ecosystems which have special function and forms by amphibious mutual effect.Human activities severely affected wetland evolution.The marine resources are rich and human activities severely affected shoreline evolution.In particular,since the reform and opening up in 1978,the heat of coastal development has continued to rise.Mainland China has been experiencing a massive sea reclamation,which has resulted to extremely rapid degradation and loss of coastal wetlands since the 1950 s.This article studied on the evolution process of coastal wetland and its correlation with human activities,and analyzing the changes of coastline and reclamation evolution are conducive to the sustainable development of coastal regional economy and the supervision and management of decision-making departments.Meanwhile,it was of great significance for administrating and protecting wetland resources.The spatial-temporal evolution characteristics of the coastal wetland and shoreline under the action of sea reclamation were researched based on the remote sensing images in nine years(1980,1985,1990,1995,2000,2005,2010,2015 and 2017).The MNDWI method,transfer matrix of land use,the fractal dimension method,landscape pattern analysis and regression analysis were used in the study.These data were processed by 3S technology and the soft wares of e Cognition9.0,Fragstates4.2,Arc GIS10.2and SPSS.The results show that:(1)Yellow River delta,Laizhou bay,Bohai bay and Liaohe River delta changed a lot,the natural wetland area decreased by 45.37%,whereas the artificial wetlands expanded by 57.23% in past 30 years.Aquatic farm and salt field increased the most significantly,which were mainly changed from moor and intertidal zone.Much natural wetland converted into urban construction land,and natural wetlands became more artificial.(2)The landscape pattern tended to be broken and equalized.And the dominant landscape types have declined in the research area.Meanwhile,the landscape heterogeneity decreased due to the strong human disturbance.(3)Yellow River delta,Laizhou bay,Bohai bay and Liaodong bay changed a lot,the natural shoreline length decreased by 80%,whereas the artificial shoreline increased by 1977.9km in past 40 years.The fractal dimension of shoreline has been increased and tended to zigzag.(4)Sea reclamation occupied a large area of natural wetlands such as moor and intertidal zone while the area increased by 1988.5km2 during 1980-2017.construction land is the main land.(5)This study presented that the national policy and economic factors drastically affected the coastal wetlands evolution.The main driving forces of the Bohai Rim coastal wetland evolution were human activities,including farmland reclamation,urban construction,and tidal flats exploitation,etc.(6)There is a significant linear relationship between the reclamation process and the change of the length of the coastline.To sum up,the the reclamation evolution affects the changes of shoreline.The main driving forces of the Bohai Rim shoreline evolution were human activities,including aquaculture,farmland reclamation,industrialization and urban construction,etc.