喀斯特地区干旱灾害风险区划研究——以遵义市为例

Risk Regionalization of Drought Disaster in Karst Region—A Case Study of Zunyi City

喀斯特地区干旱致灾机理复杂,干旱灾害风险普查技术规范方法对干旱致灾机理考虑不全面,导致以县级行政区为评估单元的干旱灾害风险区划成果与历史旱灾成果协调性不足,成为贵州省干旱灾害风险普查的一项难题。自然灾害风险理论作为干旱灾害风险区划的基础理论,基于自然灾害风险理论构建具有喀斯特特色的干旱灾害风险区划指标体系进行干旱灾害风险研究,可为干旱灾害风险区划提供依据。以遵义市为例,基于自然灾害风险理论,分析和遴选喀斯特地区干旱灾害风险代表性指标,构建旱灾风险区划模型,采用专家打分法和熵权法组合赋权,使用ArcGIS的分位数法分级,进行干旱灾害风险区划研究。结果表明:(1)地表水干旱危险性指数、地形综合指数、耕地面积和旱地占比、农村集中供水率和耕地有效灌溉率分别为致灾因子危险性、孕灾环境脆弱性、承灾体暴露性和抗旱减灾能力的主要影响因子。(2)遵义市各县区干旱灾害风险等级以中风险及以下为主,占比64.3%,中高风险区和高风险区累积占比为35.7%。(3)干旱灾害风险整体呈现东北高西南低的分布格局和区域性分布特征。高风险区分布在东北部,中高风险区分布在北部,中风险区分布在东部,中低风险区分布在南部,低风险区主要分布在中部。通过与全国抗旱规划等成果数据对比分析,验证了区划结果的合理性,可为当地开展干旱灾害防御工作提供科学依据。

Mechanism of drought disaster in karst areas is complex,and the technical specification method of drought disaster risk census does not consider the drought disaster mechanism comprehensively,resulting in insufficient coordination between the drought disaster risk zoning results with the county-level administrative regions as the assessment unit and the historical drought disaster results,which has become a difficult problem in the drought disaster risk census in Guizhou Province.As the basic theory of drought disaster risk zoning,the natural disaster risk theory constructs a drought disaster risk zoning index system with karst characteristics based on the natural disaster risk theory to conduct drought disaster risk research,which can provide a basis for drought disaster risk zoning.Taking Zunyi City as an example and based on risk theory of natural disasters,the representative indicators of drought disaster risk in karst area are analyzed and selected,a drought risk zoning model is established,the weight of drought disaster index system is determined by coupled weighting method of expert scoring method and entropy weight,and quantile classification using ArcGIS,and drought disaster risk zoning research is carried out.①The results show that surface water drought hazard index,terrain composite index,cultivated area and proportion of drylands,rural centralized water supply rate and effective farmland irrigation ratio are the main influencing factors of the drought hazard,environmental vulnerability,exposure of the values at risk,and capacity to prevent or mitigate drought disaster,respectively.②The drought disaster risk level of all counties and districts in Zunyi City is mainly medium risk or below,accounting for 64.3%,and the cumulative proportion of medium-high risk areas and high-risk areas are 35.7%.③The overall drought disaster risk shows a pattern of high distribution in the northeast and low in the southwest and regional distribution characteristics.High-risk areas are distributed in the northeast,medium-high risk areas are distributed in the north,medium-risk areas are distributed in the east,medium-low risk areas are distributed in the south,and low-risk areas are mainly distributed in the middle.Through a comparative analysis with the national drought relief program and other related data,the rationality of the zoning results is verified,which can provide a scientific basis for the local drought disaster prevention work.