Evaluation Method And Empirical Research Of Emergency Hedge Function Of Urban Public Green Space Based On GIS

Environment issues caused by urban development are continuing to worsen in terms of the acceleration of urbanization. The construction of urban green space is being paid more attention, because of its function of air purification, entertainment, aesthetics, disaster prevention and reduction, etc. The combinative construction of urban green space in order to improve the city environment ,beautify the city landscape and strengthen the function of disaster prevention and evacuation hedge has become the important content of urban construction and sustainable development."Speeding up the construction work of emergency shelter according to the relative planning and standard in capital cities and cities with more than 1 million people", is proposed in"National Plan for Public Emergency System Construction during Eleventh Five-Year Plan". Therefore, strengthening defense, controlling urban disasters and reinforcing the urban comprehensive disaster prevention and mitigation capacity is the top priority of our work at home and abroad. Urban green system occupies the very important position in urban comprehensive disaster prevention and mitigation system.In this thesis, the concept and function of urban green space were elaborated firstly, and then the roles of urban green space in emergency evacuation were discussed based on the types, factors and characteristics of urban disasters. Based on the predecessor's evaluation methods for urban public green functions, a new evaluation index systemfor emergency hedge function of urban green space was established, including the index of accessibility, the service scale of urban green space (the service area and the service population) and the index of evacuation ability ; afterwards, the evacuation hedge function in Hefei city was analyzed based on the above indices by Network Analyst module in ArcGIS 9.2.The result showed that the evacuation hedge function of Ecological Park is much better than others, due to its good transportation accessibility, large service area and more service population and strong evacuation capacity. Despite of the strong capacity of population and large service areas in Xinghua Park and Huachong Park, the transportation accessibility are relatively weak and their comprehensive scores are low. Xiao Yaojin Park, which located in the central part of the researched area, owns good transportation accessibility because of geographic location advantages,, conversely got the low score because of its weak evacuation capacity, small service area and little service population.The case data revealed that the advantages and disadvantages of emergency hedge of urban green space were objectively reflected by the evaluation index system. Comparing with the traditional investigation method, this new system can obtain the evaluation index data quickly and accurately. It is hoped that the above evaluation data and conclusions could provide the reference for the construction and reform of urban public green system, which would be helpful for playing roles of urban public green space in disaster prevention and mitigation as well as the protection of urban ecology system.