| City,a form of spatial agglomeration for the development of human society,develops under interaction among natural,economic,and social factors.Rapid urbanization indicates great achievements of urban construction,however,it can encroach production and ecological lands and then cause ecological and environmental problems.Therefore,higher request for urban development is put forward to resolve conflict between development and protection.Moreover,reasonable use and spatial optimization layout of urban land is necessary for urban construction due to the limited land resources.Urban as a complex adaptive system.Considering the regularities of urban internal self-organization,the research of exploring the best plan for urban sustainable development through model simulation has received widespread attention.Thus,this study based on analysis of urban driving forces and interaction among various decision-makers to obtain conversion rules,and then constructed the Cellular Automata and Agent Based Model(CA-ABM)to realize dynamic simulation of urban evolution and predicted the trend of urban expansion,which provided a reference for spatial optimization layout of urban land.The study took the eco-economic belt along the Yellow River as study area,and then analyzed its characteristics of evolution and urban driving forces.Through RS,GIS,SPSS,Python,ArcGIS and Vensim softwares to built CA-ABM model and simulated.After that,this study set up three development scenarios,built a system dynamics model based on statistical data from 2012 to 2018 to predict the scale of urban land use in 2025 and 2035,used the CA-ABM model to predict spatial optimization layout of urban land,discussed the regional scale of arid and semi-arid ecologically fragile areas urban development issues,and proposed schedule advice.Main results and conclusions were as follows:(1)Based on the Google Earth Engine(GEE),used Landsat imagery,DEM,NDVI,NDWI,and NDBI to establish classification features.Random forest algorithm was selected for remote sensing interpretation to obtain land use classification data of the study area in 1989,1999,2009,and 2019.The result was that the kappa coefficient was greater than 0.9,and the overall verification accuracy was greater than 80%;(2)Based on the urban compactness,urban expansion intensity,land use transfer matrix and expansion type identification,the characteristics of urban expansion along the study area from 1989 to 2019 were analyzed.The results showed that between1989 and 1999,the type of urban expansion was dominated by leaping expansion,and disordered expansion was common;from 1999 to 2009,it entered a period of rapid expansion,mainly edge expansion;from 2009 to 2019,urban expanded steadily.During this period,undeveloped land within the city has been fully utilized,and urban compactness has increased.From 1989 to 2019,urban land proportion increased from0.34% to 4.18%.During 30 years,urban area has increased by 12 times,and the city has expanded significantly,mainly due to the occupation of cultivated land,unused land and grassland;(3)Based on the theory of CA model and ABM,analysis of urban driving forces,quantification of attraction of the driving factors to urban development,this study constructed CA-ABM.The initialization probability of CA and ABM were obtained by the binary logistic regression analysis and decision-making behavior of the resident agent,the developer agent and the government agent respectively.Then,this study built CA-ABM and input land use data in 2009 to simulate land use in 2019.The result of the overall accuracy and kappa coefficient reached 97% and 0.7respectively,indicating the model simulation result is credible;(4)Based on the forecast results and urban development goals and orientation,this study proposed schedule advice for the eco-economic belt along the Yellow River.Its expansion under three scenarios showed differences: under scenario of rapid economic development,urban expansion accelerated,arable land was occupied by urban land to meet urban development;under scenario of keeping current development,urban expansion slowed down,and this expansion was increased by occupation of land around the city;under scenario of ecological protection,urban expansion was significantly controlled,and urban land increased slightly.Schedule advice were as follows: define forbidden construction area based on the red line of ecological protection and basic farmland protection;delimit urban development boundaries,make full use of undeveloped land within the city,and develop compact cities;take Yinchuan as the development center to strengthen the connection with Shizuishan City and Wuzhong City to formed the development pattern of the Yinchuan Metropolitan Area.With Zhongwei City as the starting point,vigorously develop the southern area along the eco-economic belt along the Yellow River.A new urban space system with coordinated development,spatial allocation optimization and reasonable layout,should be constructed based on the function orientation of each city. |
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