Analysis Of Spatial And Temporal Variation Of Land Use Inzhoushan City Based On Remote Sensing

Land resources are the material basis for human survival and rational use of land resources is necessary for maintaining sustainable economic development.Zhoushan City is a typical island city which belongs to hilly island landform and lacks for high-quality land resources.For Zhoushan City,land supply is a crucial restricting factor of economic development and it is very important to make rational use of existing land resources to provide space for economic activities.In recent years,Zhoushan City is in the acceleration of urbanization,land development,and reclamation as the result of the layout of the marine economic industry and the continuous growth of the resident population.Consequently,the land use pattern has changed significantly.Therefore,it is necessary to understand the characteristics of spatial-temporal variation of land use pattern and its associated factors.In this study,based on remote sensing,7 Landsat images were classified by supervised classification to get the land use data from 1984 to 2016.The land use dynamics indicators,gravity center migration,landscape indexes,and overlay analysis were applied to analyze spatial-temporal pattern changes including the quantity change,spatial change,transfer characteristics,and reclamation process.Then the main associated factors of land use change were analyzed by correlation analysis and stepwise regression method.The main findings of the study are as follows:(1)The area of construction land continued to increase and the continuity of spatial distribution has enhanced.In 32 years,the construction land area increased from 19.57 km~2to 131.51 km~2,and the expansion ratio was 572.03%.By encroaching on cultivated land/grassland and a large number of reclamation projects,the construction land has gradually extended from the two main urban areas of Dinghai and Shenjiamen on the southern coastal plain of Zhoushan Island to the entire coastal plain of Zhoushan Island and the southern islands of the study area.The gravity center of construction land migrated from south to north by 1.8 km,and the spatial distribution coordination increased.(2)The area of cultivated land/grassland reduced significantly and the spatial distribution tended to be discrete.In 32 years,the area of cultivated land/grassland decreased from 220.70 km~2 to 159.10 km~2,with a reduction ratio of 27.91%.Due to the expansion of construction land,the contiguously distributed cultivated land/grassland in the coastal plains of Zhoushan Island and the inter-mountain basin are gradually encroached.The existing cultivated land/grassland is mainly located in the coastal plain of the western half and the inter-mountain basin in the central area of Zhoushan Island.The gravity center of cultivated land/grassland migrated from south to north by 0.55 km,and the continuity of spatial distribution is significantly reduced.(3)Sea reclamation is an important way to provide space for the development of Zhoushan City.After 1999,the scale of sea reclamation has gradually increased.By reclamation,28.44 km~2 of tidal flats in the study area were transferred out,of which67.79%were converted into construction land.And 45.45 km~2 of land was obtained through reclamation,of which 65.96%was converted into construction land.By sea reclamation,the total area of the study area increased by 8.89%which has alleviated the pressure on land supply but has also greatly impacted coastal ecology and the environment.(4)Correlation analysis shows that population,people's living standard,overall economic development level,development of various industries,and construction investment scale are the significant socio-economic associated factors of land use change in Zhoushan City.Stepwise regression analysis shows that:a).GDP is the main socio-economic associated factor for construction land and there is a mutual promotion between the regional overall economic development level and the area of construction land.b).Total grain output is the main socio-economic associated factor for cultivated land/grassland and the shrinking of agricultural planting will promote the reduction of cultivated land/grass area,resulting in a decrease in total grain production.c).The population is the main socio-economic associated factor for the study area's total area and tidal flats.population growth will promote the reduction of the tidal flat area and the study area's total area,while the development of tidal flats and reclamation will provide new space for urban construction and economic development,which will promote the resident population.This study will help to understand the characteristics of land use change and the socio-economic associated factors in Zhoushan City,and provide data support for the rational decision-making of land resource management in Zhoushan City and promote the sustainable use of land resources.