Accessibility Research Of Main Parks In Lanzhou Based On GIS Network Analysis

An urban park green space,as an important part of a city,embodies natural elements of the city,and provides a place for urban residents to have a rest and enjoy themselves.In an urban ecosystem,it is one of the very few elements that can adjust the ecological structure,thus functioning as a key measure of the ecological construction level of a city.The quantity and quality of urban green spaces determine the image of a city and also influence the life quality of the city's residents.They protect the overall environment of the city,maintain urban ecological stability,and increase the diversity of species while improving the people's living environment and reducing impacts of various urban disea ses.Lanzhou,a city newly listed as a nationally designated garden city,has reached a relatively high level in terms of the construction and development of urban green space system.But it is crucial to develop ways to maintain the current level and reac h a higher level.It is the biggest green land space planning task for Lanzhou to figure out how to reap both ecological benefits and social service benefits by constructing a more reasonable urban green space system through more reasonable spatial structure planning and adjustments.Based on the Landsat TM spectral satellite imagery of July 2016 and Lanzhou city the map of Lanzhou and supported by the technologies of remote sensing(RS)and geographic information system(GIS),the present research will get the vector database of long range planning such as urban roads,parklands and rivers by digitalization.Then the digitized vector image will be compared with the high-resolution remote sensing images from Google Earth.Apart from that,field investigations will be combined with to correct conflicting surface features,and different types of parklands will be distributed to different layers so as to get a more accurate vector map database of the roads,parklands and rivers in Lanzhou.Questionnaires will also be sent out to figure out people's traveling habits.Accessibility,despite of the insufficient attention paid by the planning laws of China,can actually better serve green space planning and construction when used as a measure of the serviceability of park green land spaces.What's more,it has been written into laws and put into practice by many foreign countries,which provides enough experience for us to learn from.As a strip-shaped city built along both sides of the Yellow River,Lanzhou is unique and typical on studies of its park system's accessibility.Most domestic studies have focused on cities on plains,such as Shenyang,Zhengzhou,and Beijing.Thus,research on the accessibility of park green space system in Lanzhou has great theoretical and practical significance,available to offer ideas and suggestions to the further planning of the city's park green space planning system and road system.In this study,the Landsat TM spectroscopic data satellite imagery in July 2016 and the map of Lanzhou were taken as reference objects.The current geographical locations and situations of urban roads,water bodies and green spaces in Lanzhou were obtained on a computer by employing the powerful computation function provided by Geographic Information System(GIS).In addition,long-range planning situations of these land features were grasped through analysis of the planning map,with a map being made through vector calculation.After a field survey and a questionnaire survey were conducted,and park coord inates were corrected for a second time,a more precise vector map showing urban roads,park green spaces,and water bodies of Lanzhou were drawn by processing layers separately,and then the map was made into a database to facilitate the study.In the mea nwhile,people's travel habits revealed in the questionnaire was made into statistical data.Based on the vector map of Lanzhou made through digitization,the administrative map was clipped.The land features were classified into two types,namely,the current and the planned,and then a network analysis model was built according to road topology map and GIS network analysis module.On this basis,a map and a list were made based on a resistance cost model and through analysis of park accessibility of Lanzhou with park entrances and exits as source points.The clipped administrative map was used as a base map to obtain the accessibility ranges of urban park green spaces in different periods(10min,15 min,and 30min)of Lanzhou urban park green space accessib ility planning.Then,the analysis was carried out by making a separate map for key parks.A comparative analysis was made of the current situations and long-range perspectives of urban green space planning in Lanzhou according to the analysis maps,and an evaluation was performed on the planning's rationality,with questions and suggestions being proposed.Specific suggestions for improving the green space construction of Lanzhou were proposed to address the existing problems in the park green space system.(1)Enclosures of small parks should be removed,and more entrances and exits of large parks should be built.(2)Additional small street park green spaces should be built actively and the existing park facilities should be maintained with more efforts.(3)Roof greening should be expanded appropriately and road network structures should be planned rationally.