Study On Distribution Pattern Of Main Urban Greenbelt In China

The distribution pattern of urban greenbelt determines the urban ecosystem's benefit,which is also an important index that measures the urban environment,people's quality for life and the urban development level.This paper investigated the main distribution pattern of urban greenbelt in our country by collecting fundamental data,constructing rational model of greenbelt,as well as parameter estimation and some application.Firstly,this paper analysed the number,the distance,the area and proportion as well as the shape index of different greenbelts with the method of principal component analysis?PCA?,which mentioned about 385 pieces of greenbelt in 32 cities for the purpose of optimize the distribution of greenbelt in our country.The conclusions showed that:?1?The number of greenbelts was between 7 to 13 while the area was less than 2 square kilometer for most cities.The distance between greenbelt is between 0.4-0.8?relative distance,no units?.The shape index of different greenbelt is between 1-1.5.?2?We thought the five cities had the best greening namely Beijing,Guangzhou,Nanjing,Shenyang and Hangzhou among the 32 cities.However,there still remained some cities demanding further improvement and management,including Shijiazhuang,Fujian,Lanzhou,Haikou and Lasa.?3?The number,area,distribution of location and shape of greenbelt obtained by PCA can be used as the indicator to evaluate rationality of urban green space distribution pattern,as which have bigger influence on the urban greenbelt distribution pattern.Secondly,this paper build the appraisal model of distribution pattern from the angle of own attribute about greenbelt?including the influence of area and distance between greenbelt and shape?and the overall?including the distance between greenbelt,the proportion about service area of greenbe and the city?.?1?Based on the influence of area,this paper determineed S_A = f?A?=kA^m?specific parameter in the formula was listed in the text,the same below?.?2?Based on the influence of the distance of the greenbelt,this paper determined S^R = g?r?= e^-?r.?3?Based on the shape about greenbelt,the shape index of different shape about greenbelt is determined.?4?Based on the distance between greenbelt,this paper determined S_d²= f?d,n??the specific expressions can be found in the text?.?5?Based on the service scope about greenbelt,this paper determineed W = f?S_Y,S_C??the specific expressions can be found in the text?.?6?Based on the distribution location about greenbelt,this paper determined W = f?S_Y,S_C??the specific expressions can be found in the text?.On this basis,ecological model that evaluate the rationality of distribution pattern for greenbelt was build.Then according to the investigative data about 385 pieces of greenbelt,we estimated the parameters.Finally,we calculated with the model mentioned before and taking Baoding as concrete object.The results showed that:?1?The index of distribution pattern of Baoding was 0.096,which was unreasonable.?2?There are 7 pieces of greenbelt in Baoding whose number is lower than the majority of cities in China?7-13?.The average area of greenbeltis 0.45 square kilometer and it's smaller than the general.The shape index is 1.41 and the average spacing is 0.35?indication with deviation,no unit?,both of which are reasonable.What's more,the distribution location was 0.57 kilometer?indication with polygon center distance?which is unreasonable.Besides,the impact service area of greenbelt is too small,only 0.3133.?3?In view of the current distribution pattern of Baoding,We suggested that increase the number of greenbelt at first,especially large area of greenbelt.At the same time,we can extend the perimeter of greenbelt as far as possible on the premise of same area.