| Urban heat island effect is one of the most significant characteristics of urban climate.With the rapid development of urbanization,the intensity and scale of urban heat island are increasing.Urban greening and water bodies can have positive effects on alleviating heat island effect.Reasonable microclimate adaptability of urban riverfront park is beneficial to alleviate urban heat island effect,maintain ecological balance,and form a harmonious and comfortable living environment.This study quantifies the spatial morphology and structure characteristics of riverside park,discusses the contribution proportion of each spatial morphology and structure index of riverside park space to air temperature and the marginal effect threshold.And on the basis of microclimate effect simulation and conclusion analysis,the scenario analysis method is adopted to classify the green space of riverside park according to the overall structure and functional zoning.The paper summarizes the spatial pattern types of microclimate adaptability of different types of riverside parks,and then controls and guides the layout optimization of riverside parks.Twelve typical riverside parks in Shanghai were selected as research objects,and basic data of rivers and green spaces in the riverside parks were obtained through satellite images,and microclimate data were obtained through ENVI-met simulation.The index system of spatial pattern structure affecting the differentiation of internal microclimate distribution of riverside park is constructed,including 13 factors in three dimensions.The planar morphological factors include area of plant landscape space,proportion of tree area,proportion of shrub area,proportion of grass area,proportion of square area,proportion of park path area,and landscape shape index.The three-dimensional spatial factors include three-dimensional green volume,vegetation enclosure type,and open space height to width ratio.The spatial structure factors include distance from the riverbank,canopy density and d PC.GIS spatial analysis and mathematical statistics were used to analyze the spatial pattern pattern of the riverside park,and then the boosted regression trees model(BRT)is used to analyze the contribution and marginal effect of various factors on air temperature,and the microclimate characteristics of plant landscape space in the riverside park is analyzed.The study divided the typical spatial pattern types of riverside park into five categories: central agglomeration type,polycentric dispersion type,fragmented patch type,fragmented corridor type and combined pattern type.Each type of pattern has different spatial microclimate distribution characteristics.The distribution of temperature in the central agglomeration type park shows the pattern of high temperature in the central area and low temperature in the periphery.The distribution of wind speed showed a pattern of high wind speed in the central area and low wind speed in a large area outside.The relative humidity showed a pattern of low humidity in the center and high humidity in the periphery.The temperature distribution of the polycentric dispersion type park shows the pattern of mass high temperature and flake low temperature.The distribution of wind speed showed the pattern of mass high wind speed and sheet low wind speed.The relative humidity showed a pattern of high humidity in the middle and low humidity in the periphery.The temperature of the fragmented patch type park showed a pattern of low temperature in large patches and high temperature in small patches.The wind speed in the ventilation corridor is larger,but the wind speed in the arbour dense area is smaller.The relative humidity showed the pattern of high humidity in large areas and low humidity in small areas.The temperature of the fragmented corridor type park showed a pattern of banded low temperature and patchy high temperature distribution.The wind speed presents the pattern of high wind speed belt corridor and low wind speed clumps concentrated or distributed in sheets.The relative humidity showed a pattern of banded areas with high humidity and patchy areas with low humidity.The distribution pattern of temperature,wind speed and relative humidity in the park of the combined pattern type was extremely uneven.The microclimate of Riverside park is affected by spatial factors.The results show that:(1)Distance from the riverbank is the dominant factor affecting the internal temperature of riverside park,and its contribution ratio is as high as 44.06%.Canopy density,three-dimensional green volume and proportion of tree area accounted for the next.(2)For the spatial structure factors,distance from the riverbank showed a significant positive correlation with air temperature,while the influence of canopy density and d PC on temperature showed a negative correlation,and the marginal effect thresholds were 90 m,0.45 and 16,respectively.(3)For the three-dimensional space factors,three-dimensional green volume and open space height to width ratio are negatively correlated with air temperature.The vegetation enclosure type also affects the thermal environment to a certain extent by influencing the wind speed,and the influence threshold is 1700m~3 and 0.6respectively.(4)For the planar morphological factors,proportion of tree area is negatively correlated with air temperature;the area proportion of grassland,square and shrub and landscape shape index are positively correlated with air temperature;the correlation between area of plant landscape space and air temperature changed from negative to positive;the correlation between proportion of park path area and air temperature changed from positive to negative.The influence threshold of proportion of tree area ratio was 45%.(5)The plant landscape space of riverside park with large area,high canopy density,high three-dimensional green volume,close to the river and large proportion of tree area often has the best cooling effect.Based on the microclimate analysis results of the spatial morphology and structure index of the riverside park,the microclimate optimization simulation of the typical spatial types was carried out,and combined with the characteristics of the park cooling pattern simulated in the previous status quo,the adaptive development model of the spatial morphology and structure of the riverside park was determined.The study finally put forward the spatial pattern of climate adaptability for the overall structure of different types of riverside parks and the spatial pattern development criteria of microclimate adaptability for plant landscape space of different functional zones under different canopy density levels. |
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