Risk Assessment On Flood In Guangzhou City

Guangzhou is one of the highest risk cities of flood disaster. With the development of the economy and society, the losing will increase, and more areas will be influenced once the flood disaster occurs. In this research, the basic characters of flood disaster in Guangzhou city is summarized, based on the historic data of flood disasters in Guangzhou city, which are uneven distribution to seasons and years, serious disaster conditions. Using the theory of flood system, the author comprehensively analyses the causes of floods in Guangzhou city from the environment, hazard, and the body of bearing the disaster.On the basis of the above researches, with the use of GIS software, the authors focus on flood risk assessment in Guangzhou City. It Primarily includes: (1) Construction of assessment model: AHP decision analysis model, and the introduction of the calculation steps of it;(2) Danger assessment of Hazard and environment: the analysis of impact from dangerous factors and production of the corresponding layers; a comprehensive danger assessment combined with the weight of each factor and production of the corresponding danger assessment map; (3) Assessment of the vulnerability of disaster including an analysis of each factor, and production of the corresponding layer; a comprehensive assessment of the vulnerability combined with the weight of each factor and producing a corresponding assessment map of vulnerability.(4) Giving the danger of the Hazard and the environment 60% of weight and the vulnerability of disaster 40% of weight respectively, then making use of GIS software to produce flood risk assessment map.After analyzing the map of flood risk assessment, the author comes to the following conclusions:The south of Guangzhou City is high-risk area and the north of Guangzhou City low-risk area; the east and the west of Guangzhou City are high-risk areas and the centre of Guangzhou City is low-risk area. The dominant factors witch lead to this pattern is the differences in height and differences of distribution of rivers. The vast majority of Nansha and Yuexiu, most of Liwan, the south, east, and north of Panyu, Plain by the middle and lower reaches of Zengjiang River, Xifu river ang Dongjiang River are the highest risk areas with a risk degrees of higher than 0.75. In these areas, we should attach great importance to the construction flood control.The vast majority of Haizhu District, the northern region of Panyu in south of University City, part of Liwan District, the east and Huangpu District, central and southern regions of Zengcheng, the western part of Baiyun District, the southern region of Huadu District and Xinhua Town in Conghua City are high risk areas with degree of higher than 0.65, in which special prevention measures should be taken.The majority of Luogang District, the east of Baiyun District, the north of Zengcheng and the north of Tianhe District are lower risk areas.The lowest risk areas distribute in the mountains in Conghua, Huadu, Baiyun, Zengcheng Luogang and Zengcheng districts (cities).The assessment results may provide reference for flood prevention and mitigation of Guangzhou city.Pointing out the necessity to change the idea of floods controlling and the importance of non-engineering measures, the author puts forward a comprehensive proposal from non-engineering measures and engineering measures.