Research On Port City Expansion And Ecological Benefit Evaluation Along The Maritime Silk Road

The Maritime Silk Road(MSR)is a trade and cultural exchange ocean route that includes a coastal belt of more than 50 port cities,of which 10 are mega cities with over 10 million inhabitants.The coastal zone along the Maritime Silk Road brings economic benefits to both land and marine industries,and port cities are hubs and nodes of the coastal zone economy.Therefore,to deepen the understanding of the mode and trend of port city growth and expansion.The environmental impacts and ecological benefits related to the status quo of road development are very important.Given the limited body of current research on the dynamics and trends of urban expansion and growth of these cities,we selected 45 port cities along the MSR in East Asia,Southeast Asia,South Asia,West Asia,Africa,and Europe,and using time series(1990-2015)of satellite imagery mapped urban expansion to analyze rates,form,and direction of growth and impact of ecological benefits.Further,we conducted comparative analyses to determine similarities and inter-and intra-regional differences in urban development processes.The main conclusions are as follows:(1)In the early 1990 s,there were only two port cities along the Maritime Silk Road with an area greater than 500 km2(Jakarta and Jeddah).Over time,this number increased 8 times in the 25 years from 1990 to 2015,with 17 ports The area of the city exceeds this standard,and the area of 10 port cities has more than doubled(ie more than 1000 km2).The areas with faster urban area growth are East Asia and Southeast Asia.From 1990 to 2015,there was a significant difference in the average annual growth rate(AGR)between the six regions,with East Asia having the highest annual growth rate(8.49%),followed by South Asia,Southeast Asia,West Asia,Europe and Africa(3.85%).(2)The comprehensive analysis of the four landscape indexes: landscape shape index(LSI),patch aggregation index(COHESION),landscape split index(DIVISION)and aggregation index(AI)LSI,COHESION,DIVISION and AI shows that the landscape shape index landscape pattern index The most irregular growth always occurs in the port cities of East Asia,Southeast Asia and South Asia.Port cities in these areas are in a period of rapid development with active development.The landscape pattern index and urban form have undergone significant changes.The urban landscape patterns in Europe,West Asia and Africa have changed relatively little in the past 25 years.The patch agglomeration of all port cities has been improved.The patch agglomeration index of West Asia,Africa and Europe has changed very little,and the value is very close to 1,especially in West Asia.Among the four landscape indexes,only the landscape split index is gradually decreasing,which indicates that the degree of urban landscape fragmentation is gradually decreasing,and the landscape integrity of urban forms is constantly improving.With the increase in the degree of urban plaque cohesion,the aggregation index will also increase.The aggregation index of all port cities is rising,while the aggregation index of West Asia,Africa and Europe is usually higher than that of East Asia,Southeast Asia and South Asia.(3)In terms of urban expansion model,enclave expansion was the dominant urban expansion model(22 out of 45 cities)from 1990 to 2000,followed by marginal expansion(14 out of 45 cities)and filling expansion(8 out of 45 cities);in the period of 2010-2015,the ratio of enclave,edge,and fill became 0.27,0.57,and 0.16,and the proportion of the edge expansion model has far exceeded the other two This expansion mode.(4)Under the influence of rapid urbanization,the land use status of port cities has undergone tremendous changes,and has had a certain impact on the surrounding ecology.In 1990-2015,the main land use types in Kuala Lumpur and Mumbai Both have changed from farmland to construction land;the main land use types in Bangkok and Haiphong are farmland,accounting for 41%-67% and 25%-36%,respectively;the main land use type in Jakarta is forest,accounting for 40%-56%.From 1990 to 2015,the construction land area of five or three port cities increased by 4.1,1.3,1.7,2.6,and 15 times,respectively,and a large amount of farmland and forests were converted into construction land;the reclamation area in Jakarta and Haiphong City showed an increasing trend,Jakarta A large amount of mangroves were lost,which decreased by 81.9% from 1990 to 2010;mangroves in Haiphong City showed an increase,decrease,and increase trend in three periods,and the area of breeding ponds increased by 82.5%.Reclamation is a relatively common land-building activity in port cities,and in the process of expansion to the sea,it will inevitably affect the ecological environment such as mangroves and breeding ponds.Reasonable planning for the expansion of construction land is the top priority to the sustainable development of future port cities.The development of ports plays a powerful role in promoting and leading the development of port cities,and they will all drive rapid economic development.The process of urbanization may continue and intensify.It is generally believed that urban development is a potential driver or obstacle to sustainable development.Future research will focus more on the impact of port city expansion on the ecological environment,and will assess the ecological environment impact of coastal city expansion.