TROPICAL GEOGRAPHY ›› 2018, Vol. 38 ›› Issue (2): 217-225.doi: 10.13284/j.cnki.rddl.003018

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Decadal Variation and Evaluation of Flood Risk based on the Combination Weight of Game Theory

ZHANG Lilan1,LAI Chengguang2,CHEN Xiaohong1,HE Yanhu1,YANG Bing1,LI Wei1   

  1. (1.a.Center for Water Resources and Environment Research;b.Key Laboratory of Water Cycle and Water Security in Southern China,Guangdong Higher Education Institute,Sun Yat-sen University,Guangzhou 510275,China;2.School of Civil and Transportation Engineering,South China University of Technology,Guangzhou 510641,China)
  • Online:2018-03-05 Published:2018-03-05

Abstract: Affected by global warming and intensifying human activities, floods have increased recently across China. In this context, the analysis of flood risk assessment and how the risk had evolved is of significance. According to disaster system theory, 10 indices were selected and classified into three driving factors that are disaster-inducing factor (Maximum 3-Day Precipitation, and Typhoon Frequency), hazard inducing environment (DEM, Slope, Distance to River, Topographic Wetness Index, Stream Power Index, and Runoff Coefficient) and hazard-affected body (Population and Gross Domestic Product), respectively. This study proposed a combination weight that combines the objective and subjective weights by game theory, and then applied the combined weight to an assessment model based on the Fuzzy comprehensive evaluation (FCE). Taking Beijiang River Basin, which is located in South China and had experienced typical urbanization during the last few decades, as a study case, this study assessed the flood risk in 1990, 2000 and 2010, respectively. According to the characteristic of the input indices, only Population, GDP and SPI were considered to evolve from time to time, while the other indices basically remain stable and represented the average annual value. The flood risk was divided into 5 levels: lowest risk, lower risk, middle risk, higher risk and highest risk; finally, the study analyzed the decadal spatial evolution during 1990~2010. After the assessment model was established, the calculating and visualization procedure were accomplished based on the ArcGIS interface. The results showed that: 1) among the 10 selected indices in the combined weight, typhoon frequency and maximum three-day precipitation were assumed to be the most important while population and GDP the least important; the combined weight determined by game theory can decide the proportion of subjective weight and objective weight, and by making some abnormal values of certain index in single weight more reasonable, it can avoid the shortcomings of one-sidedness of single weights; 2) flood risk was basically stable in Beijiang River Basin in the past two decades, where low risk zone occupied most of the basin (60%), and higher and highest risk zones took up around 20%; among the highest risk zone were the cities of Qingyuan, Huaiji, Fogang and Wengyuan, which generally have adverse natural conditions, such as greater precipitation, lowlands and gentle slopes, and denser population and more developed industries; 3) the high risk zones showed an expanded trend during the last 2 decades; and the trend was more significant in the second decade (2000-2010) than in the first decade (1990-2000) with cities of Qujiang and Nanxiong transferring from higher risk zones to highest risk zones, that is the result of the combined effort of severer changes in land used type, population and property of the basin. Regional flood risk is a combined effort of natural factors and human society, and thus it changes over time, the reveal of the evolution law in the study would be of great significance in the plan of land development and urban flood control.

Key words: Flood risk, risk variation, game theory, the Beijiang River Basin