基于GIS格网的重庆合川区森林火险等级区划

Zoning of forest fire risk levels in the Hechuan District of Chongqing based on GIS grid

【目的】了解各因子对森林火险发生的影响程度以及小尺度范围内的火险等级,生成公里级森林火险区划图,寻找潜在的高火险区域,客观认识各地区火灾风险水平并进行提前预防,为防火资源分布以及防火工作的开展提供支持与参考,为各级政府有效开展防火工作提供火灾风险信息和科学决策依据,全面提升防灭火综合应急能力。【方法】以重庆市合川区为主要研究对象,选取可燃物、地形地势以及人为因子3个方面共10个因子作为主要区划指标,通过外业调查建立标准样地,获取可燃物含水率、可燃物载量以及可燃物燃点等理化性质数据,利用30 m分辨率的DEM数据提取地形中的坡度、坡向、海拔因子,通过对遥感影像目视解译的方法获取合川区的道路与建筑物信息,并利用ArcGIS进行缓冲区分析,将所有影响因子重分类成公里级格网尺度,采用层次分析法对各个因子赋予不同的权重指标,通过加权叠置分析的方法构建风险区划模型,获取火险指数,最终确定不同区域的火险等级。【结果】计算与区划结果显示合川区极低火险区域为477.401 km^(2),占合川区面积的20.37%;低火险区域为858.306 km^(2),占合川区面积的36.62%;中火险区域为401.421 km^(2),占合川区面积的17.13%;高火险区域为339.788 km^(2),占合川区面积的14.50%;极高火险区域为267.051 km^(2),占合川区面积的11.39%。中等风险以上的火险区域面积占比较大,防火工作严峻。【结论】通过对近20年合川区高温热点数据分析验证了区划结果的精度,证实其合理性与准确性,为区域森林火灾管理工作提供指导,从而达到保护森林资源的目的。

【Objective】The article aimed to understand the influence degree of each factor on the occurrence of forest fire and the forest fire risk level on a small scale,in order to generate a kilometer-level forest fire risk zoning map,find potential areas of high fire risks,objectively understand the fire risk level in various regions and carry out early prevention.The work will provide support and references for fire protection resources and fire prevention work,offer fire risk information and scientific decision-making basis for the government at all levels to effectively carry out fire prevention work,which will improve the comprehensive emergency capacity of fire prevention and fire extinguishing.【Method】By taking the Hechuan District of Chongqing as the main research object,the research selected ten factors from three aspects as the main regionalization indexes,such as combustibles,topography and human factors.Standard sample plots were established through field surveys to obtain the moisture content and load of combustibles,as well as the physical and chemical properties data such as the ignition point of combustibles.The 30m-resolution DEM data was utilized to extract the slope,aspect and altitude factors in the terrain,and obtain road and building information in the Hechuan District by visually interpreting remote sensing images.ArcGIS was used for buffer analysis,all the influencing factors were reclassified into a kilometer-level grid-scale,and the analytic hierarchy process(AHP)was used to assign different weight indicators to each factor.The risk zoning model was constructed by weighted superposition analysis to obtain the fire risk index,and finally,the fire risk level of different areas was determined.【Result】The calculation and zoning results showed that the area with extremely low fire risks was 477.401 km^(2),accounting for 20.37%of the area of the Hechuan District;the area with low fire risks was 858.306 km^(2),accounting for 36.62%of the area of the Hechuan District;the area with medium fire risks was 401.421 km^(2),accounting for 17.13%of the area of the Hechuan District.The area with high fire risks was 339.788 km^(2),accounting for 14.50%of the Hechuan District,and the area with extremely high fire risks was 267.051 km^(2),accounting for 11.39%of the Hechuan District.The areas with moderate or higher risks accounted for a large proportion,and the fire prevention work was severe.【Conclusion】Based on the analysis of the high-temperature hotspot data of the Hechuan District in the last 20 years,the accuracy and rationality of the regionalization results are verified,which can provide guidance for regional forest fire management to achieve the purpose of protecting forest resources.