| The coastal zone is the most concentrated area of socioeconomic with high population density and obvious industrial agglomeration,which has serious eco-environmental status resulting from the destructive human-soil interaction and intensive reclamation activities.Due to irrational and intensive reclamation activities,the supporting role of coastline resources on coastal socio-economic development is restricted by the rapid decrease of natural coastline and severe destruction of coastal ecological functions.Therefore,it is urgent to strengthen the protection of natural coastline and the control of coastline utilization.The remarkable effect caused by long-term and high-intensity reclamation activities on natural coastline in Shandong continental coastal zone has been revealed based on remote sensing and GIS technology by combining time series data of reclamation and coastline evolution from1974 to 2017.Furthermore,a graded management measure of reclamation was proposed,which provide support for policymakers in the implementation of natural coastline protection policy and in the management of local coastal reclamation.The main contents and conclusions were as follows:(1)The scale,structure,and function of reclamation in Shandong province gradually increased,diversified and integrated during the research period.Overall,the cumulative area of reclamation was 4,643.51km~2 with an increase by averaging107.99km~2 annually.Reclamation has showed an periodic characteristic apparently.Before 2000,sea reclamation was the modes of reclamation activities mainly consisted of enclosed mariculture and saltern at the rate of 94.12km~2/a between 1974and 2017,which were mainly concentrated in gulf areas,such as Yellow River delta,Laizhou bay,Jiaozhou bay,and Jinghai bay;whereas later,infilling area converted into enclosing continually due to the development of urbanization,tourism infrastructure,port,and coastal industrial construction.The scale of the conversion from sea reclamation to land reclamation was about 704.18km~2 during the study period.(2)There was a significant correlation between natural coastline changes and reclamation scale,and the latter was the main driving factor of the former.Specifically,the proportion,composition,and spatial distribution of the natural coastline in Shandong province have changed significantly,which was caused by the long-term and high-intensity reclamation activities.It is reflected in five aspects:(a)the proportion of natural coastline decreased from 68.23%to 36.01%in the 1974-2017period,(b)the fragmentation level of shoreline has obviously increased,as the length of longest continuous natural shoreline from 679.79km reduce to 194.83km,(c)natural coastline resource was becoming tighter,except for Yellow River delta,the proportion of natural coastline was less than 35%.(3)The natural coastline length and tidal flat scale decrease significantly under the influence of reclamation.In detail,the total length of the natural coastline occupied by reclamation was 1063.56km from 1974 to 2017.Since a large number of muddy coastlines are occupied by enclosed mariculture and saltern,there was the most grievous period with a speed of 56.53km/a in 2000-2007.The total loss of tidal flat is 1702.90km~2 with an average annual decrease of 39.60km~2,of which the Yellow River Delta,Laizhou Bay,bays in the east of the peninsula,and estuary areas suffer the greatest loss.Other coastlines,such as the bedrock harbor coastline at the eastern harbour of the peninsula and sandy coastline,have been utilized at different degrees due to the rapid development of urbanization and industrialization.(4)The indicator system for graded management of reclamation was proposed by combining the marine ecological red-line policy.To support for the protection of natural coastline and control the speed and scale of reclamation,156 coastline paragraphs of Shandong province were divided into 6 restriction levels,and corresponding management regulations have been put forward. |
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