Mapping the flood disaster risk of metropolitan region in the Yangtze River Delta of China

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Yin ZHOU1,2, Jing'ai WANG1,2,3, Wei XU3,4, Yao ZHOU1,2 …

Yin ZHOU1,2, Jing'ai WANG1,2,3, Wei XU3,4, Yao ZHOU1,2

1School of Geography, Beijing Normal University, Beijing 100875, China; 2Key Laboratory of Regional Geography, Beijing Normal University, Beijing 100875, China; 3State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China; 4Academy of Disaster Reduction and Emergency Management, Ministry of Civil Affairs & Ministry of Education, Beijing 100875, China

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  • I will introduce my research from this five aspects.

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  • 1. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of China Mapping the flood disaster risk of metropolitan region in the Yangtze River Delta of China Speaker : Yin Zhou Tutor : Jing’ai Wang Key Laboratory of Regional Geography Research School of Geography, Beijing Normal University
  • 2. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of China OUTLINE 1. Introduction 2. Methodology and materials 3. Selection of Class Intervals 4. Result of Flood Risk Map 5. Conclusion and Discussion
  • 3. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of China1. Introduction China is among the few countries in the world with a relatively large variety of highly destructive natural disasters (Shi, 2011). 2 000 human lives 30 billion dollars
  • 4. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of China1. Introduction The Yangtze River Delta, which is one of the most developed regions in China, contributed to 17.6% of China’s overall GDP in 2010 In the past thirty years, 119 floods were recorded, which seriously threaten the regional economic development.
  • 5. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of China1. Introduction •Maps can reflect the spatial pattern of disasters clearly, and contribute to better understanding of fundamental laws of disaster system. •The maps are needed urgently when disasters outbreak, and the automatic mapping which enhances the mapping efficiency greatly has become a research hotspot. •The data classification is an important part for automatic mapping.
  • 6. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of China1. Introduction In risk mapping, most classification schemes that have been proposed are based on the properties of the datas statistical distribution without regard for the datas spatial distribution. we should consider spatial regularity while selecting class intervals.
  • 7. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of China2. Methodology and materials The flood disaster risk in Yangtze River Delta is evaluated by Hazard, Exposure and Vulnerability, that is R = H ⊗ E ⊗V The hazard formative factors consist of rainfall, frequency of rainfall, terrain and water system. The exposure factors include property density, population density and land use. The vulnerability factors include physical vulnerability and the capacities for disaster reduction.
  • 8. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of ChinaSelection of Class Intervals •The selection of class intervals can strongly affect the visual impression given by a map. •When the number of classes is determined, class interval is the only factor that affects the result of classification. •Class intervals are determined by classification method
  • 9. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of ChinaSelection of Class Intervals •The flood risk in the Yangtze River Delta Region is ranked to five levels: high, relatively high, medium, relatively low and low. •Equal intervals, geometric intervals, quantiles, natural breaks, mean standard deviation are the most common methods for data classification .
  • 10. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of ChinaSelection of Class Intervals Terrain Distance from coastline Water influence Land use coverage
  • 11. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of ChinaSelection of Class Intervals •Flood disaster is prone to the areas with lower elevation. According to water level statistical data, Yangtze River Delta is divided into four parts by elevation: 2m, 2~5m, 5~10m, ≥10m. Elevation < 2m 2~5m 5~10m ≥10m Weight 0.50 0.30 0.15 0.05
  • 12. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of ChinaSelection of Class Intervals Generally , flood disasters occurs more frequently in the areas that near the coast line in Yangtze River Delta. Distance < 40km 40~80km 80~120km ≥120m Weight 0.45 0.35 0.15 0.05
  • 13. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of ChinaSelection of Class Intervals The influence of water is mainly decided by river density and the distance from the rivers. Flood disasters often occur in the area that near the river. And the influence caused by rivers is different, such as the Yangtze River influences much stronger than small rivers. Buffer distance/kilometers first-order river Second-order river Inner buffer Outer buffer Inner buffer Outer buffer 8 12 6 10
  • 14. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of ChinaSelection of Class Intervals The property density is various with different types of land use coverage. The exposure of land decreases by: urban land, rural land, farmland, grassland, forest and water bodies. Land use type urban rural farmland grassland forest water bodies Exposure 0.30 0.25 0.22 0.10 0.08 0.05
  • 15. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of ChinaSelection of Class Intervals The spatial correlation coefficient between flood disaster risk and the constraint layers can be calculated out. Flood Disaster Risk Terrain 0.37357 Land use 0.34379 Water Influence 0.28514 Distance from Coastline 0.12683 Ri=0.37357*R1i+ 0.12683*R2i + 0.28514*R3i +0.34379*R4i
  • 16. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of ChinaSelection of Class Intervals Mean Classification Equal geometric Natural Quantiles Standard Method Intervals intervals Breaks Deviation correlation 0.56199 0.48921 0.53176 0.56804 0.52121 coefficient
  • 17. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of ChinaResult of Flood Risk Map
  • 18. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of ChinaConclusion and Discussion This article has realized the intelligent selection of classification method of the flood disaster risk based on the constraint layer. The constraint layers don’t include disaster prevention and mitigation capacity, which are also very important to the disaster risk pattern. Selecting proper factors to represent disaster prevention and mitigation capacity and finding the spatial pattern of those factors are the further work should be done.
  • 19. Mapping the flood disaster risk of metropolitan regionin the Yangtze River Delta of China