北京市雷电灾害易损性分析、评估及易损度区划

根据1995—2005年北京市18个区县的雷暴日和雷电灾害统计资料, 结合北京市的经济和人口密度特征, 提出了雷暴日数、雷电灾害频度、生命易损模数及经济易损模数作为北京市雷电灾害易损性评估指标, 并在此基础上, 给出了北京市雷电灾害易损度评估结构。采用4级分区法对上述雷电灾害易损性评估指标进行了分级, 并赋予各等级如下定值:极高级为1.0, 高级为0.8, 中级为0.5, 低级为0.2。将北京市18个区县按照4个雷电灾害易损性评估指标的所属等级获取相应等级值, 将各区县4个评估指标的等级值累加, 得到平均值作为雷电灾害易损性评估的评价指数。最后通过对北京市各区县雷电灾害易损性进行综合评估, 并利用4级分区法形成北京市雷电灾害易损度区划。结果表明:城区和丰台区为雷电灾害极高易损区, 海淀区、朝阳区、昌平区和石景山区为雷电灾害高易损区, 延庆县、大兴区、门头沟区和平谷区为雷电灾害低易损区, 其他区县为雷电灾害中易损区。

Vulnerability Analysis, Evaluation and Vulnerability Zoning of Lightning Disaster in Beijing

Based on the lightning disasters, thunderstorm days, economic and population data of eighteen counties in Beijing during 1995—2005, vulnerability analysis, evaluation and vulnerability zoning of lightning disaster are made. The analysis on spatial distribution of annual mean thunderstorm days in Beijing shows that there are more thunderstorms in the north than those in the south, and more thunderstorms in the west than those in the east. The thunderstorm activities in Miyun district are the most, whose annual thunderstorm are more than thirty-five days. The least thunderstorm activities exit in Tongzhou district, whose thunderstorm days are less than twenty-five.The study on spatial distribution of lightning disaster frequency indicates that more lightning disasters occur in the city zone and near the suburb than in the remote suburb.There are more dwellers in the city zone and near the suburb than in the remote suburb, and regarding GDP (gross domestic product) the former is more than the latter. It suggests that the thunderstorm activity is not the only cause for lightning disaster in Beijing. The lightning disaster might also relate with the population density and the economy in the disaster area.The vulnerability of lightning disaster might include two factors at least :the criticality of the disaster and the frangibility of the disaster area. Therefore, four indices are selected to evaluate the vulnerability of lightning disaster in Beijing. They are annual mean thunderstorm days (M), lightning disaster frequency (P), economic vulnerability module (D) and vital vulnerability module (L).M is used as a measurement of nature thunderstorm activity in Beijing. P is historical lightning disaster frequency.D and L are used to scale the economic and population characters of disaster areas respectively. Firstly, the four indices are classified into four degrees with a given value as follows:the extreme high degree is 1.0, the high degree is 0.8, the intermediate degree is 0.5, and the low degree is 0.2. Secondly, the comprehensive vulnerability evaluation index of lightning disaster is obtained by adding the degree values of the four indices. Then the comprehensive vulnerability evaluation index for the eighteen counties is also graded as four degrees, which are defined as the maximal damageable area, the high damageable area, the medium damageable area and the low damageable area. Finally, vulnerability zoning of the lightning disaster is obtained based on the vulnerability degree values of the eighteen counties in Beijing. The result shows that the city zone and Fengtai district belong to the maximal damageable area. Haidian district, Chaoyang district, Changping district and Shijinshan district belong to the high damageable area. Yanqing district, Daxing district, Mentougou district and Pinggu district belong to the low damageable area.The rest districts belong to the medium damageable area. Scientific basis might be provided for the planning of regional prevention and reduction of lightning disaster in Beijing.