Study On Thermal Environmental Impact Factors And Evaluation Models Of Urban Regulatory Detailed Planning

Since 1980 s,the urbanization process in China has been accelerating year by year,and with more widespread urban ecological environment problems at the same time.Among them,urban heat island,which has changed the urban heat environment,affecting the regional climate,air quality,urban soil physical and chemical properties,urban biological distribution and behavior,and many urban ecological processes,is one of the causes of a series of ecological environmental problems.By the beginning of nineteenth Century,the British climologist Luke Howard first put forward the concept of "heat island effect" in the "climate of London",and many scholars at home and abroad have carried out extensive and in-depth research on this problem.However,the current research is mainly focused on the status,harm and influencing factors of urban heat island,and the research of reduing heat island by urban planning is relatively inadequate in the early stage of urban development.In recent years,some research on the combination of urban planning and heat island is mainly focused on the study of the heat island effect on large scale urban master planning by using WRF and MM5 models,and the study of the heat island effect on small scale site planning by using CFD model.There are few studies on the heat island effect on the mesoscale urban regulatory detailed planning.In this study,remote sensing（RS）,geographic information system（GIS）,computational fluid dynamics（CFD）and other technical methods are used,and combine remote sensing inversion,ground measurement and fluid simulation to study the influence of different scale planning and design indicators on urban thermal environment.Based on CTTC model,the method of thermal environment simulation and evaluation for urban regulatory detailed planning is established,and the combination approach of regulatory detailed planning and cluster thermal time constant（CTTC）model is put forward.1.Using the three Landsat5 satellite image data in summer,autumn and winter,the heat island situation in the central city of Guangzhou is analyzed.It is considered that:（1）There are obvious seasonal differences in the distribution of urban heat island;（2）In summer,the maximum contribution rate of heat island is 10.3% from the second residential land,followed is about 8% from industrial land and roads;（3）The industrial land is the main source of the heat island,the contribution rate is between 8%-10% in three each season;（4）The water E1 and the woodland E4 are the most important cold sources,the contribution rate is between 20%-40%,and followed by 3%-4% from the park green space.2.The land surface temperature of 2954 urban construction lands are extracted in the central city of Guangzhou,in order to studing the influencing factors of the urban scale thermal environment.（1）In summer,the influence from the surrounding environment is greater than that from self-construction on the thermal environment of land parcel.（2）In autumn and winter,the influence factors of the thermal environment are similar,the influence from the surrounding environment and self-construction also are similar on the thermal environment;（3）Single factor regression analysis indicates that the surface indicators（eg.the building density,the distance and proportion of the cold source,and so on）mainly affects the thermal environment in summer,and three-dimensional indicators（eg.plot ratio,average standard deviation of building height,and so on）mainly affect the thermal environment in autumn and winter.（4）Multivariate linear regression analysis shows that the main factors of the summer thermal environment are E1234G1₁00,the main factor in autumn is PR₁00,the main factor is Hstd in winter;（5）the influence from the surrounding environment is greater than that from self-construction on the thermal environment of 100 m grid,and the weight of surrounding indicators gradually decreases when the grid scale=>200m.（6）When the grid scale=>200m,the three indicators of PR₀,E1₀ and E1234G1₀ have the most weight in regression equation,and continue to increase with the increase of grid scale.3.The air temperature of three measurement areas which is about 64 hectares in the Guangzhou University Town was measured,in order to studing the influencing factors of the urban block scale thermal environment.（1）The urban construction indicators of 100 m buffer zone around the temperature measurement point have great influence on the temperature;（2）the six indexes of SVF,open space proportion,concrete proportion,the coverage rate of tree and grassland,plot ratio are more explanatory capability to the heat island.（3）The index of ADL（the air temperature is divided by the land surface temperature）is put forward to dividing temperature measurement points into three categories,and the discrimination method of temperature measurement points is researched by the binary logistic regression model.（4）A regression model of air temperature whose independent variable is land surface temperature was built,the adjusted R equation was 0.8894,and the standard error was 0.7951.4.Base on the CTTC model,a thermal environment assessment model for urban regulatory detailed planning is put forward by meshing the planning scheme.The calculation methods of key grid indexes,such as SVF,hourly shadow rate,absorption coefficient of solar radiation,CTTC,sun shading and evaporation,are put forward.A grid wind speed ratio calculation model considering the influence of surrounding environment is proposed with great prediction accuracy.The mean error of CTTC model in all-day is basically within ±0.5℃,about 2.5% for the mean error rate,about 4% for the maximum error rate,and the mean error in daytime is within ±1℃,about 4% for the mean error rate,about 7.5% for the maximum error rate.5.Research on the combination approach of regulatory detailed planning and CTTC model.（1）9 new thermal environment control indexes of urban regulatory detailed planning,include the floor height,the water rate,the crusty surface proportion,the proportion of the asphalt material in the crusty surface,the proportion of the pervious surface in the crusty surface,the sunshade coverage rate of the structure,the number of trees in the 100 ㎡ green space,the proportion of green roof,are summed up.（2）According to the analysis of the current land use index,the relevant requirements of the policy documents,criterions and standards,the default values and the recommended values of the thermal environmental indicators for each type of land use are proposed.The main innovations of this paper are as follows:（1）The index system of urban-scale thermal environmental impact factors is constructed from three aspects: the index for itself,the index for the surrounding environment impact,and the distance from cold and heat sources.The thermal environmental characteristics and impact factors in summer,autumn and winter are analyzed by using large samples of urban construction land.（2）The index system of thermal environmental impact factors at block scale was constructed from four aspects of building,hard paving,material and greening.The calculation methods of concentric circle and ring were compared,and the index of “air-land temperature ratio” was put forward.（3）Base on the CTTC model,a thermal environment assessment model for urban regulatory detailed planning is put forward,and research on the combination approach of regulatory detailed planning and CTTC model.（4）A grid “wind speed ratio” prediction model considering the influence of upper wind direction is put forward.