摘要
全球气候变化加剧和城镇化快速推进使得洪涝灾害发生频率和破坏性显著升高,为应对洪涝灾害利用风险评估指导村庄居民点布局优化,以福建省长汀县为例,运用模糊综合评价方法划定洪涝风险等级区,通过双重目标决策法对村庄灾害风险和发展潜力进行综合评价,并基于引力模型确定村庄迁移方案.结果表明,长汀县洪涝灾害高风险区域主要分布在以汀州镇与大同镇为主体的集中建设区及以部分村庄居民点,针对高风险村庄居民点,以"避灾"为导向提出了村庄迁移合并方案,实现了村庄居民点布局的适灾和减灾优化调整.对于区域防控洪涝灾害、减少灾害损失具有重要作用,对山地村庄空间防灾减灾规划实施有较强指导意义.
Abstract
The frequency and destructive impacts of floods increase significantly due to intensifying climate change and rapid urbanization.Nevertheless,village settlement layout planning based on risk evaluation of flooding requires further exploration.Based on analysis of flood generation mechanisms in Changting County,Fujian Province,an index system was built using fuzzy comprehensive evaluation from the perspective of disaster-inducing factor risks and sensitivity of disaster-inducing environment.Changting County was divided into different flood disaster risk grades by building a fuzzy membership function.Based on flood risk evaluation in Changting County,the disaster risk levels within village administrative boundaries were determined.Villages were evaluated comprehensively by the dual-goal decision plane method according to disaster risks and development potential.Villages were divided into five development types:priority development,size control,potential optimization,characteristic protection,and evacuation for integration.Finally,the gravity model(which was improved based on the cost-distance method)proposed specific strategies for evacuation villages.Research results show that high-risk zones in Changting County present the spatial distribution pattern of"one zone,multiple points"."One zone"refers to the concentrated construction area centered on Dingzhou Town and Datong Town,covering an area of about 12.38km2."Multiple points"refers to the high-risk nodes scattered in different towns and villages,mainly Cewu Town,Hetian Town,Nanshan Town,Tufang Town,Zhuotian Town,Gucheng Town,and so on.The underlying surface conditions influence occurrence of flood disasters to a significant extent.The increased hard construction lands decrease rainwater infiltration and surface roughness,increasing local surface runoff and thus intensifying the risk of flooding.Evacuation for disasters becomes an important mean for village areas with a small population density and scattered settlements to cope with natural disasters.For 10 evacuation villages recognized according to comprehensive assessment,the gravity model based on the cost-distance method was applied to determine specific directions for evacuation by observing the principle of nearby evacuation.Moreover,suggestions for evacuation order of villages were put forward with comprehensive considerations for emergency level of flooding and evacuation cost.A reasonable evacuation layout can not only effectively avoid natural disaster risks,but is also more conducive for villages to integrate land resources for intensive development,thus increasing utilization and service scope of public service facilities.This study optimizes the scientific disaster-prevention layout of village settlements in Changting County,provides methods and theoretical references for spatial planning practices orienting to flood disaster prevention and reduction,and provides some guidance for village evacuation planning to cope with natural disasters.
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