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　　摘要:為推動城市公園綠地應急避險體系建設的發展，在評價指標體系的指導下，應用GIS的空間插值技術，對北京城市人口統計數據進行了空間分布化，并通過人口密度分布與公園綠地緩沖區的疊加分析，對城市公園綠地的人口服務輻射能力進行了探索研究。結果顯示，整個北京規劃市區內公園綠地的緩沖區覆蓋范圍總計為421.96km2，約占規劃市區面積的38%，存在626.46km2的服務盲區。另外，規劃市區東部、北部和西南最外圍區域大多數辦事處中所含的公園綠地緩沖區占其行政區面積的比例均低于10％。在分析基礎上，還進行了公園綠地應急避險功能布局的設想。

　　Abstract:In order to promote the urban park development for emergency and disaster-prevention functions, the urban population spatial distribution is carried out with the guidance of the evaluation index system and the application of the GIS spatial interpol methods, and the population service radiation capability of urban park green space is studied through the superposition analysis of the population density distribution and the park buffer zones. The results show that the total area of park buffer zone in Beijing city proper is 421.96km2, 38% of the total urban planning area, while the uncovered service space is 626.46km2. In addition, most of the park buffer zones in furthest periphery of the east, north and southwest parts of the planning area are less than 10 percent of their administrative area. Finally the layout of emergency and disaster-prevention functions of park green space are proposed on the basis of the analysis.

　　文章部分內容:

4 北京城市公園綠地應急避險功能布局的設想

　　4.1 基本目標和原則

　　在保證城市綠地發揮其景觀、生態功能的同時，為了保護人民生命財產的安全，實現構筑布局合理、不同服務半徑層次基本覆蓋，居民能快速到達一個避險場所的城市公園綠地應急避險功能體系的目標。

　　在綜合考慮各方面因素的基礎上，即結合北京地理自然條件(西北部為西山的延伸部分；東南部為平原地區，以農業用地和農田作物為主，宜林綠地面積大，便于城市綠化發展)、現有綠化現狀、楔形綠地規劃、水系分布、山體分布因素，在推動城市綠地建設的發展過程中，根據以人為本、科學性、可操作性、就近和系統性原則進行布局設想。

　　4.2 城市公園綠地應急避險功能布局的設想

　　為配合2008奧運會，2005年北京已制定《北京中心城地震及其他災害應急避難場所(室外)規劃綱要》，逐步將八大城區的一些公園綠地改造為配有應急避險設施的真正意義上的避災疏散場地，目前北京中心城已建成與公園綠地有關的24處應急避險場所[8]。

　　在本布局設想中，根據城市園林綠化現狀、功能及規劃原則，在保持《北京市區綠地系統規劃》(2002年)的基本結構基礎上，結合城市公園綠地的人口服務輻射能力分析以及現已建成的應急避險場所，主要采用“綠環、多中心點、多通道”的公園綠地網絡拓撲結構進行布局設想，具體為：

　　(1)“綠環”，即由環繞城市的二環、三環、四環和五環路兩側綠化形成多個綠環(圖6)，兩側的帶狀綠地各劃定不低于道路紅線寬度，與其他道路主干道形成交叉節點，形成拓撲結構和緩沖地段，遇到意外災情可盡快疏散城市人口，保證城市居民安全。

　　(2)“多中心點”，即根據現有公園綠地的地理位置、規模(不含水體)和功能等屬性，選擇性地作為應急避險的救護中心，并將面積在50hm2以上的非公園綠地規劃為應急避險的救護中心。最終，通過分析比較，考慮到城中心(指四環之內區域)已建成了分布相對密集的應急避險場所，從城市的發展和均衡的角度，偏重于郊區和衛星城區域，共選擇了23處綠地建議作為應急避險的救護中心，其中包括13處面積在50hm2以上的非公園綠地，和10處面積在30hm2以上的公園綠地。

　　(3)“多通道”，即包括長安街、南北中軸道路、主干道及兩側的帶狀綠地，形成似玫瑰圖形的放射形疏散主通道網，將救護中心、躲避空間聯系起來(圖6)。

　　另外，從(圖6)所對應的服務半徑分析可以得出，所布局設想的綠地500m服務半徑緩沖區覆蓋范圍基本可以覆蓋郊區的西南和東南區域(限于篇幅，相關圖表不在此列出)，東北區域可結合楔形綠地，從易于管理的角度，宜以公園為主的改造建設形式，進行改造或增加新的綠地。

　　The Layout Study on the Emergency and Disaster-prevention Functions of the Green Space of Beijing City Parks

　　XIE Jun-fei, LI Yan-ming, LI Shu-hua

　　1 Preface

　　In urban green space system, urban parks, with wide space, perfect facilities, low density of building, can provide excellent emergency shelter condition. Due to learn more emergency and disaster-prevention functions of urban green space system, Chinese government began to pay more attention to the green space construction with emergency and disaster-prevention functions. But, at present, studies mostly focused on qualitative description, it needs quantitative spatial assessment in-depth, and needs to know how to perfect the planning of urban emergency adapting system within urban whole layout frame, and how to raise park population radiation capability.

　　In this study, to present a optimization proposal for the layout on emergency and disaster-prevention functions system of urban park in Beijing, according to evaluation index system, spatial distribution of Beijing population statistical data was done with spatial interpolation methods of Geography Information System (GIS), meanwhile, based on dot, line, side entity in vector database, the analysis on buffer zone with different radius around parks were carried out, finally, the relevant problems about population service radiation capability of park were studied, based on the maps overlap of population density distributing and buffer zone of park.

　　2 Study area and data

　　In this study, the study region was determined according to Beijing urban planning boundary, and was shown in Figure 2, in which total area is 1 097km2, the objectives of this research are park green spaces(excluding its water region)in the study region, the basic vector data of park green space all obtained from Beijing urban green space investigate database in 2005, which were provided by Beijing Municipal Bureau of Parks. All the data layer were registered to the same Beijing local coordinates system and resampled to the same pixel resolution of 0.6 m.

　　3 Actual status analysis on population service radiation capability of parks in Beijing urban planning

　　3.1 Spatial distribution of population statistical data based on GIS

　　In order to accomplish spatial distribution of population, The first step is to scatter GIS vector element detail consisted of 125 street offices. The second step is to collect the total population data within 125 street offices(based on 2005 green space general investigation document), finally, spatial distribution of population statistical data based on GIS was done with the Kernel estimation method.

　　Figure 1 showed that the population density was biggest in center urban region, there is a descending trend for population density from center to urban suburb, which was coincidence with the actual population distributing condition. The estimated population density in gridding region was mostly consistent with statistic value. The estimated population density in urban planning extension was 5 000 per square kilometer.

　　3.2 Buffer zone analysis on urban park

　　In the present study, in order to identify parks influence on its external environment, based on operation between buffer-zone analysis and union module of Arc view software, a certain exterior buffer zone was extracted by 1 500 m, 1 000 m and 500 m service radius around park (excluding parks itself). Table 1 and Figure 2 showed the buffer-zone cover 421.96 km2, the cover area account for 38% of the total planned urban area (the overlapped parts of buffer zone had been resolved). Another, there be 626.46 km2 which was unable to access emergency shelter service, which was neither belong to park nor belong to the buffer zone.

　　Taking street office as the basic administrative units to be accounted, the buffer zone in the eastern, northern, southwestern street offices of the urban suburb accounted for less than 10%, the buffer zone of most street offices in the sub-regional accounted for less than 25%. With economic development, the new large-scale communities are constantly emerging, in order to provide equal opportunities of choice and sound hedging space in dealing with natural disasters and other emergencies, it is necessary to undertake a green space layout from the perspective of emergency shelter.

　　In the central city, the data showed that the coveraged area about buffer zone amount to 70.25 km2, with another 16.39 km2 of areas unable to access emergency shelter service. The buffer zone of Xicheng district covered the largest area of 25.21 km2, which constitutes 79.35% of the overall administrative area, followed by Xuanwu district, which constitutes 78.42% of the overall administrative area.

　　3.3 Analysis of the population service radiation capability of urban park

　　Based on the grid maps overlap of buffer zone and distribution map of population density in urban planning area, finally, the results were obtained that population density of the buffer zone was 10 586 per square kilometers, if multiplied by 421.96 km2 of buffer zone, the population within the coverage of the service were 4.47 million. Considering altogether 7.02 million population registered in the city, there were still more than 2.55 million of people had no access to the emergency shelter service.

　　Theoretically, according to demand that everyone has 2 m2 green space at emergency shelters, if the park with 5 000 hm2 all was rebuilded emergency shelters under the hypothesis condition, there only were 4.47 million of people which had access to the emergency shelter service within service radius. But, every park is not only single purpose for emergency shelters, but also they should afford more complex function in fact.

　　4 The design of park layout on emergency and disaster-prevention functions system in Beijing urban planning

　　As part of the preparation for 2008 Olympics, Beijing developed the "Beijing Downtown Earthquake and Disasters Emergent Shelter (Outdoors) Program" in 2005. The program designed some parks and green spaces in eight districts in downtown Beijing as real disasters shelters with emergency facilities. By now there have been constructed 24 emergency shelters in urban areas.

　　In current study, the design was developed according to the present plant coverage, function and development guidelines. It was based on the basic structure of the "System Layout of Beijing Urban Green Lands"(2002) with consideration of population absorbing capabilities of parks and the existing emergency shelters. The design consisted of a topology network of parks with "green belts, multi-hubs and multi-passages".

　　(1)Green belts: there were belts of plant covered areas along the 2nd, 3rd, 4th and 5th ring roads of Beijing. The green belts on both sides of the roads were not less narrow than the road red lines, and formed a network of buffer zone with pathways to other main roads for evacuation of populations in case of emergent disasters.

　　(2)Multi-hubs: emergency rescue and aid hubs were carefully selected based on the geographic locations, size (excluding water areas), functions of present parks et al., Green spaces (not parks) with lands over 50 hm2 were designed as the emergency rescue and aid hubs. In the program, we recommended 23 green spaces in suburb and satellite towns around the city to be constructed as emergency rescue and aid hubs, including 13 green spaces (not parks) with over 50 hm2 of area and 10 parks with over 30 hm2 of area.

　　(3)Multi-passages: passages included Chang'an Street, center-axis road connecting north and south, main roads and green space on both sides of these roads. These passages formed a actinomorphic network of evacuation passages that connect rescue hubs and shelters together.

　　In addition, the buffer region as shown in Figure 5 can cover most areas including southwestern and southeastern suburb with 500 m service radius around the green space. Northeastern region can be covered with reconstruction of present wedgy green space or new green space. It was recommended that the reconstruction be done based on present parks for easier management.

　　5 Conclusions and perspectives

　　From this study, the following major conclusions could be drawn:

　　(1)In the urban planning area in Beijing, buffer zone of park total was 421.96 km2, accounted for 38% areas of the overall program, with another 626.46 km2 of areas unable to access service.

　　(2)With in the planned areas, the average population desity for buffer zone was 10 586 people per square kilometers. If multiplied by 421.96 km2 of buffer zone, the population within the coverage of the service were 4.47 million. Considering altogether 7.02 million population registered in the city, there were still more than 2.55 million of people have

　　no access to the emergency shelter service.

　　(3)Based on future growth and balance of the city, 23 pieces of green spaces in suburb and satellite towns were recommended as emergent rescue and aid hubs, with main roads in the city connecting them together as a network of evacuation.

　　Aim of key problems of urban park emergency, the paper mainly discussed the methodologies and technical ways of emergency rescue and shelter in city areas. More precise conclusions can be achieved based on more detailed information of population distributions.

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　　作者簡介:謝軍飛/1976年生/男/湖南人/碩士/工程師/北京市園林科學研究所/研究方向為城市生態評價(北京 100102)

　　李延明/1965年生/男/教授級高級工程師/北京市園林科學研究所(北京 100102)

　　李樹華/男/博士/教授/中國農業大學觀賞園藝與園林學系(北京 100094)