Theory And Method For Multi-scale Measurement Of Mixed Land Use

With the change of urban spatial development pattern from incremental expansion to inventory optimization,land use pattern changes from single function to mixed function has become an important way to urban transformation under resource constraints.However,limited to our country's stage of social development and the traditional understanding to organized spontaneously of land use mix,the mixed land use research progress is lagging and slow.With the introduction of western theories,new concepts are re-interpreted,domestic scholars held different opinions and have no consensus,which restricting the standardization of theoretical research.At the same time,mixed land use practices are emerging continuously under the government dominated or the spontaneous force of markets,but still lack of supports of method systems or guide systems,which hinding the scientific exploration of mixed land use pattern.The measurement research of mixed land use tries to establish the connection between theory and practice through technical methods.This study firstly explores three basic problems: firstly,from the perspective of land as spatial resource,it rerecognizes the mixed organization model as the entry point of mixed land use measurement;secondly,from the perspective of the stability of land use system,Analyzes the core features of "mixing" and "combination" and explores the mixed space organization mechanism;thirdly,by summarizing,improving and innovating the existed measurement methods and forming the methods basises.On the basis of identifying the problems,the triangular theory framework of mixed land use measurement is proposed.Using this framework and take Shanghai for example to explore the spatial pattern of land use mix from multiple scales of community,streets(town),regional respectively,and further exploring relationships between mixture and community,mixture and partition,mixing and compact.The main research results and conclusions are as followed:(1)Land is a kind of multivariate composite space resource,mixing space organization should reflect the ternicity space: absolute space composed of element attributes,relative space of element structure expression,relational space of element function reflection that as the entry points of mixed land use measurement.Mixed land use as an element structure function system,the goal is to promote a mutually beneficial symbiotic relationship among areas,avoid the high cost or high frequency of Land conversion or urban modification,therefore,the stable operation of the mixed organization mechanism requires three necessary conditions: the composition of mixing elements should meet the diversified demands of human beings;the mixed space structure should strengthen the urban spatial connection and social integration;the mixed functional relationship should activate the positive externality of land.The compatibility judgment matrix is established to improve the existing compatibility measurement methods and promote the full expression of the connotation of "mixed".(2)Based on the recognition of mixed space organization,the stability mechanism of mixed space organization and the integration of mixed quantification methods,the triangular framework of mixed land use measurement is established: diversity of mixed elements;accessibility of mixed space structure and compatibility of mixed functional relations.Three parts contact each other become one: diversity of mixing elements is the basis of mixed judgment,accessibility of mixed spatial structure enables individualized attribute identification into collectivized regional comparison,compatibility of mixed function relationship enables different land types to form a mutually beneficial and symbiotic relationship network.Analysises from the scale of the "community" to "street(town)" to "city " based on the triangle frame,try to reflect the personality of small scale,identification of medium scale,commonality of large scale,a more comprehensive understanding of mixed land use spatial characteristics.The results show that:(3)Community scale.Shanghai had planned 23 large residential communities since 2009,which mainly consisted of government-subsidized housing and low-priced commercial housing.Because of the large number,widely distributed and large scale,these communitites would have a profound impact on suburban living space.Results show that the mixed degree of residential communities are not high,accessibility and compatibility are the main influence factors,high-mixed mainly dependent on advantage resources of administrative centers or suburban new cities,but low-mixed large dwellings are often remote,less accessible,and lack of conditions for mixed development.The mixed development of large residential communities should be a gradual process.(4)Streets(town)scale,22 are high-mix of Shanghai's 216 streets(towns)which mainly distributed in the city center,unmixed are 42 with compatibility is the main limiting factor.Land use mix show the spatial agglomeration characteristics,the high concentration of the street(town)are 50,accounted for 23.1%,low concentration of 17,accounted for 7.9%.By integrating "mix","agglomeration" and "dominant function of land",the mixed space can be divided into two categories,one is high-mix of residential,high-mix of services,high-mix of residential and services,the other is low-mix of residential and industry,low-mix of residential industrial services.The comparison of the mixed degree is relative,compared with the rigid exclusive partitions,based on the mixing classification is a kind of tolerance partition,in principle,to encourage diverse land use types coexist in the same area with the exception of incompatible or significantly external types of land.Mix and partition are not binary logic that black or white,they are dialectically unified(5)Regional scale.High-mix area account for 16.4% of Shanghai which distribute in the city center,especially the Jingan district,Huangpu district,Hongkou district(high-mix proportion are higher than 85%),unmixed area account for 7.5% that mainly distribute in Baoshan district,minhang district,jiading district and other suburban areas(high-mix proportion are less than 25%).The analysises of land use mix characteristics of construction land control pattern,industrial distribution pattern and basic farmland protection pattern show that mixing degree of central construction area is higher than outside the central construction area,inside the outer ring is higher than outside the outer ring,there is no significant difference in the degree of mixing within and outside the basic farmland reserve.Further explore spatial relations between mix and compact show that the consistency of area accounted for 18.8%,high-mix and high-compact areas mainly distribute in urban core and suburban new town which are the main space of urban complex function carrier.According to the above research results,from the Angle of multi-scale,give the strategies on practices and management of mixed land use: firstly,the mixed characteristics of different scales show different structural properties,and the streets(towns)show organizational complexity,street(town)is the core scale of the coordination between the top-down mixed space layout optimization and the bottom-up mixed human land relationship,and could be the best point and starting point of mixed land use theory and practice.Secondly,mixed land use practice should development progressively from diversity,accessibility,compatibility,combine with regional characteristics,clarify the stage of regional development and the spatial scale of mixed practices,small scales are encouraged to establish mixed residential units and the service units,large scales with high mixing conditions areas should be given priority.Thirdly,by improving top-down land use guidance and encouraging bottom-up creativity,a dynamic and stereoscopic mixed land use management system is established,emphasizing dynamic thinking and hierarchical management.