Port City Expansion And Its Ecological-environmental Effects

Port city plays a vital role in the construction of the 21 st Century Maritime Silk Road.Port city expansion is one of the most striking features of urban development in Southeast Asia and South Asia in recent decades,with the characteristics of late urbanization,extremely high urban primacy ratio,unbalanced urban development and so on.In order to scientifically understand the law of port city development and its impact on urban ecological environment,and reveal the interaction between human activities and natural ecological environment,this study selects four cities along the Silk Road as study areas to explore the port city expansion and its ecological environmental effects,and we expect to provide data support for the sustainable development of port city.The four cities are Haikou,Bangkok,Kuala Lumpur and Colombo.Based on Landsat data and MODIS data,the port city expansion from 1990 to2015 and its ecological environmental effects are analyzed,and the coupling coordination model is used to evaluate the coupling coordination development relationship between economic efficiency and eco-environmental benefits.The main study contents and conclusions are as follows:(1)Port city expansion.From 1990 to 2015,the built-up land areas in Haikou,Bangkok,Kuala Lumpur and Colombo had increased continuously.Among this four cities,Haikou urban expansion was the fastest,followed by Kuala Lumpur,the next one was Colombo,and the Bangkok expansion was the slowest.Urban expansion patterns in Haikou were edge-expansion pattern and outlying pattern,in Bangkok were edge-expansion pattern and infilling pattern,in Kuala Lumpur's first period were edge-expansion pattern and outlying pattern,in Kuala Lumpur's second period were infilling pattern and edge-expansion pattern,in Kuala Lumpur's third period was edge-expansion pattern,and in Colombo were edge-expansion pattern and infilling pattern.Urban expansion in four cities had experienced the conversion from outlying pattern to edge-expansion pattern and then to infilling pattern,which was conform to the Diffusion-Aggregation theory.In Haikou,urban expansion speed of the region near to city center was higher than that far away from city center,however,in Bangkok,Kuala Lumpur and Colombo,the urban expansion speed of the region far away citycenter was higher than that near to city center.In addition,study result showed that Haikou,Bangkok and Kuala Lumpur were in irrational expansion status,because the urban expansion rate significantly exceeded the population growth rate.(2)Eco-environmental effects of urban expansion.Vegetation greenness in Haikou and Kuala Lumpur increased from 2000 to 2015,but in Bangkok and Colombo decreased.In four cities,the region of vegetation greenness significantly decreased was in accordance with the urban main expanded region.In Haikou,Bangkok and Colombo,vegetation greenness of the region closed to city center was decreased,but in Kuala Lumpur,vegetation greenness of the region closed to city center(10km or less)was increased.In the urban significant expansion region in Haikou,Bangkok and Kuala Lumpur,there was a significant negative correlation between NDVI trend and urban annual increased areas,it meant urban expansion leaded to vegetation greenness decrease.(3)Evaluation of coupling coordinated development level of economic efficiency and eco-environmental benefits of port cities based on coupling coordination model.Among Port Haikou,Port Bangkok,Port Klang and Port Colombo,Port Klang was the largest port because of its biggest areas and longest shoreline.With the exception of Port Bangkok,Port Haikou,Port Klang and Port Colombo had experienced expansion from 1990 to 2015,and the most prominently expanded port was Port Haikou,Port Colombo followed,Port Klang expansion was relatively slow.Haikou economic efficiency and eco-environmental benefits were increased from 1990 to 2015,at the same time,the coupling coordination development level of economic efficiency and eco-environmental benefits became higher and higher.