Research On The Partition Of Asylum Circle For Mountain Cites Based On GIS

Various and high frequency of disasters will bring about disaster chain in hill terrace environment in our country.Except for prominent contradictions between human and environment,a large amount of excavation and fill give rise to high occurrence of geological disasters in fragile hill terrace environment.Shelters, as a part of refuge system for cities, have been built in large quantities so as to improve the anti-disaster capacity of cities and reduce losses and damages by disasters in developed countries.Conventional asylum circle partition of two-dimension stage has been applied to research and practice on this area in our country, especially in mountain cities, which relatively lagged behind developed countries. Method above is unsuitable for mountain cities because not only valid asylum circle can’t be gained by conventional partition,leaving serious hazards for taking refuge when disasters come.According to the land use pattern, its own characteristics, surroundings and area,four places have been chosen as cases, including Chongqing Jiaotong University,Datianwan stadium, Jinyun square and Flower garden respectively for education, sports,square and garden. Methods, including filed measurement, had been applied to acquire true and effective area of refuge, profile data and minimum-distance between two points, which played a vital role in analyzing factors influencing asylum circle and finding out partition of asylum circle for mountain cites.During the investigation and analysis of typical cases, it has been realized that the main factors affecting the asylum circle can be dissociated and quantized by formulation derived from horizontal, linear and actual distances. Results show that factors including distance, road network and landform arrange form high to low.Knowing the factors and its actual manifestation, partition principle of asylum circle for mountain cites can be concluded from theoreticalresearch and practical accomplishments by predecessors. Partition principle of asylum circle for mountain cites based on GIS(Geographic Information System) can be acquired by means bellow.Firstly, main road for refuge should be found out, and then service points in different directions can be confirmed so as to dividing the area surrounding the shelters.Eventually, GIS can be applied to figure out and integrate the asylum circle.Finally, asylum circle built in Beibei district of Chongqing has been taken as a case to verify the partition of asylum circle for mountain cites, which is simple and accurate for now on account of quantifying three main factors and giving full consideration to shelter itself and its surroundings. It can be also known that maldistribution of shelters planning did exist in Beibei district on account of large overlapping range of asylum circle, especially leading to shelters’ not meeting the evacuation of permanent resident population in the suburbs and outskirts.