| The rapid development of urbanization and extended expansion had caused the urban sprawl and other issues,it has had a significant impact on the effective development of urban land,the intensive use of the space,and the sustainable development.For promoting the compact and intensive development of the urban,controlling urban sprawl by demarcating urban land development boundaries,has become one of the effective means to alleviate urban problems.In order to effectively solve the problems faced by current urban land expansion and restrain the disorderly spread of cities and guide the rational development of cities,we delineated rigid protection boundary and elastic development boundary based on the point of view of resource and environmental carrying capacity.Specifically,the suitability of construction land and population carrying capacity were evaluated by the guidance of the concept of ecological priority and astute growth,and scientifically identify the most suitable land for construction and development.The main findings of this article are as follows:(1)We selected 14 factors for evaluation from three aspects including natural conditions,spatial accessibility and ecological conditions.Among them,four factors including the permanent basic farmland protection zone,the ecological red line protection zone,the nature reserve,and the prohibited construction zone are used as rigid ones;ten factors including slope,elevation,The quality of cultivated land,sudden geological disasters,the type of land use,the distance from rivers,the distance from railways,the distance from national roads,the distance from highways,and the distance from built-up areas are used as elastic ones.The suitability scores of the evaluation units for construction and development were calculated by the limit condition and suitability index methods,then K-means clustering method was used to determine the adaptability level of evaluation unit.The suitability assess results of construction land indicate that the area of highly-suitable and moderately-suitable accounted for 57.36%of the total area of the central urban area of Guixi city,and the ratio of suitable construction and unsuitable construction was 2.58:1,with a total of 5660.01 hm~2 belong to unsuitable construction.In order to protect the ecological safety bottom line,it is necessary to strictly control the development and construction in the study area.(2)The maximum size of the population can be calculated based on the evaluation of land and water resources carrying capacity,and the population size in 2025 can be predicted by using the gray model(GM(1,1))and the natural growth rate method,however,it should not exceed the maximum population size that can be carried for ensuring the rationality of the predicted population in the study area.The predict results show that it has a population of 372,800 in the central urban area of Guixi city in 2025 and the newly-added population will be 98,200 from 2017 to 2025.The per capita construction land use index method predicts that the central urban area of Guixi city reaches 6820.42hm~2 in 2025,and the newly-added urban land area is 1080.2 hm~2.(3)The boundary area of the rigid protection zone is 5660.01 hm~2 in the central urban area of Guixi city,accounting for 27.94%of the total study area.This is an insurmountable boundary for the construction and development of the central urban area of Guixi city,including the permanent basic farmland protection areas,the ecological red line protection areas,the nature reserves areas,and the prohibited construction areas.Strict ecological protection policy should be implemented for the land within the boundary,and all development and construction activities for the purpose of pursuing economic interests should be prohibited.Outside the boundary,it is a suitable development area and also the largest area that the central urban construction land can be expanded,which ensure the maximum development limit of the central area while ensuring that the ecological safety bottom line is not damaged simultaneously.(4)In 2025,the area of the elastic development boundary in the central urban area of Guixi city is 6820.42 hm~2 and the newly-added land size is 1080.2 hm~2 from 2017 to 2025,which is consistent with the projected new scale.The area of newly-added land in highly suitable is 783.22 hm~2,accounting for 72.51%of the total area;of moderately suitable land is 296.98 hm~2,accounting for 27.49%of the total area.There are no lowly-suitable or unsuitable lands for construction and development in new construction land areas,and the expanded land quality is generally high and mainly develops in the southwest,northeast,and north.The newly-added area of construction land was 555.65 hm~2,224.46 hm~2,and103.24 hm~2 respectively,accounting for 51.44%,20.78%and 9.56%,respectively.The new amount of these three positions reached 81.78%that more than half of the total newly-added amount.The construction land expansion intensity is the largest,which is consistent with the analysis results of the extended direction prediction;the newly-added construction land area in the Western industrial park is 87.62 hm~2,accounting for 8.11%of the total newly-added amount;the central old and southern parts of the city also have a small amount of expansion,with the area of 109.22 hm~2,accounting for 10.11%.All the newly-increased construction land is located in the type area of HH(high-high)space agglomeration,and the land construction and development suitability grades are high and most of the surrounding areas are higher suitability for construction and development,showing a certain degree of homogeneity and spatial agglomeration is relatively good.The elastic development boundary should fully utilize natural ecological landscape elements such as Xinjiang river,Luotang river,Xiangshan forest park,Shanghai-Kunming high-speed railway,and Zhejiang-Jiangxi railway,based on the concept of ecological priority and smart growth,it is divided into four districts including the area of Chengbei,Chengzhong,Chengnan,and Chengxi,form the development pattern of“one city,two rivers,three banks,and one train of four axes and four zones”.(5)Compare the results of the delineation of the elastic development boundary with the general land use planning and urban master planning,we could analyze the rationality of the results in the central urban area of Guixi city with two aspects.The rationality analysis of the elastic development boundary can be verified by three aspects:the extension of strength and orientation,the distribution of land construction and development suitability in unbuilt areas,and the spatial agglomeration pattern.In 2025,the scale of newly-increased land use in the development boundary will mainly expand in the southwest,northeast,and north,accounting for more than half of the scale,which is consistent with the predicted expansion.All newly-increased land was distributed in highly-suitable and moderately-suitable areas,and there are no lowly-suitable and unsuitable land for construction and development,located in the HH(high-height)space agglomeration type areas,which has good spatial agglomeration and is conducive to the promotion of intensive land use;generally,the expanded land quality is higher and the rationality is stronger relatively.Compare the results of the land use and urban master planning with our results that the expansion and the evaluation of the suitability of construction land,on the one hand,our results were consistent with the regulations;on the other hand,existing construction land is located in lowly-suitable land and unfavorable area in land use and urban master planning,where there was prohibited from construction and development within the rigid protection boundary,but our results that the determination of the newly-added construction land was located in the highly-suitable and moderately-suitable areas in the urban land development boundary.Therefore,it is more realistic and reasonable,and could better protect the ecological environment,maintain ecological security,and promote the rational development of the city than the land use and urban master planning. |
PDF Full Text Request