| The Guangdong-Hong Kong-Macao Greater Bay Area is the fourth largest bay area in the world,with unique advantages in geographical location and marine resources.In the economic development of China’s Bay Area,the Greater Bay Area plays an important role as a strategic pillar.In recent years,with the rapid economic development and population growth in the Greater Bay Area,the scope of land reclamation in the Greater Bay Area has continued to expand,and the coastline has changed rapidly,which has had a huge impact on the balance of coastal ecosystems and the sustainable development of resources..Therefore,the research on the temporal and spatial changes of the coastline in the Greater Bay Area is aimed at better utilization and management of marine resources in the coastal areas of the Greater Bay Area.Based on Landsat/Sentinel images,this paper adopts the improved normalized difference water index(MNDWI)and Canny operator,and uses the optimal threshold to automatically obtain the water edge combined with the remote sensing interpretation classification method to extract the Guangdong-Hong Kong-Macao Greater Bay Area in1990,1995,and 2000.,2005,2010,2015 and 2021 seven coastline information data.Through GIS spatial analysis,fractal calculation methods and mathematical statistics,the spatial distribution,length change,fractal dimension,type structure,diversity index and endpoint change rate of the mainland coastline in the Guangdong-Hong Kong-Macao Greater Bay Area from 1990 to 2021 were analyzed.analyzed.Combined with the Pearson correlation coefficient analysis method,the driving mechanism of the coastline changes in the Guangdong-Hong Kong-Macao Greater Bay Area is discussed.Finally,two representative typical areas of Zhuhai City and Zhongshan City were selected to predict the future position of the coastline by using the Kalman filter combined with the linear regression method in the digital coastline analysis system.The main research results are as follows:(1)From 1990 to 2021,the length of the coastline in the Guangdong-Hong Kong-Macao Greater Bay Area maintained a continuous upward trend,with a total increase of 358.71 km,or a growth rate of 17.13%.The coastlines of Shenzhen City and Shenzhen City increased the most,the coastline length increased by 79.59 km and62.92 km respectively,and the coastline growth rate was 30.67% and 28.82%respectively.The change trend of the fractal dimension of the coastline is consistent with the change trend of the length.Although there is a slight fluctuation in Zhongshan City and Macao Special Administrative Region,it generally shows a continuous growth trend,indicating that the complexity of the coastline is constantly increasing.(2)During the study period,the shoreline structure changed frequently,and the natural coastline and artificial coastline ebbed and flowed.From 1990 to 2021,the artificial coastline increased by 853.95 km,and the natural coastline decreased by495.24 km.The proportion of natural coastlines decreased from 71.68% to 41.00%,among which,the bedrock coastlines decreased the most,with a reduction rate of more than 35%.The proportion rose from 10.56% to 39.59%.The shoreline type diversity index in the study area showed a trend of first increasing and then decreasing,and the shoreline type structure and shoreline type diversity index changes at the city scale were different.(3)From 1990 to 2021,most of the coastlines in the Guangdong-Hong Kong-Macao Greater Bay Area were in a stable state,and the changes were mainly manifested as advancing seaward,while fewer coastlines retreated landward.The main reason for the seaward advancement of the Guangdong-Hong Kong-Macao Greater Bay Area is man-made development and construction activities such as land reclamation and port construction.The more obvious area is Shenzhen,where the coastline has the largest proportion of seaward advancement,accounting for 56.88%.Zhuhai City is an area where the coastline recedes significantly to the land,and the proportion of the coastline receding to the land is 13.54%.In contrast,the proportion of coastline retreating landward in other areas is relatively small.The main reason for the receding coastline is natural factors such as coastal erosion caused by precipitation,sea level rise and waves.(4)Using the Pearson correlation coefficient analysis method,the role and impact of natural,economic and social factors on the coastline of the Guangdong-Hong Kong-Macao Greater Bay Area were quantitatively analyzed.At the same time,a qualitative analysis is carried out on the impact of coastline types on coastline changes.The results show that the coastline changes in the Guangdong-Hong Kong-Macao Greater Bay Area are the result of the combined effects of natural factors,economic and social factors.(5)The coastal area from Zhuhai City to Zhongshan City will continue to be affected by erosion due to the impact of roads,ports,docks and breakwaters.According to the Kalman filter prediction for 2031,the shoreline of this shore section will recede237 m landward. |
