Tempo-Spatial Occurrence Patterns Of Lightning And Risk Evaluation Of Lightning Disasters On Expressways In South Part Of Jiangsu Province

Based on the observed data of cloud-to-ground(CG) lightning location during the period from 2007 to 2013 and the observed data of intracloud(IC) lightning location of Jiangsu Province, in 2013, in this paper, the temporal and spatial pattern of CG lightning and IC lightning activities on the expressways in the southern part of Jiangsu Province were investigated. Combined with the lightning parameter data, remote sensing data, basic geographic data, statistical yearbook data, and historical statistics data of lightning disasters and supported by GIS spatial analysis function, the expert scoring method, the analytic hierarchy process (AHP), and the weighted comprehensive evaluation method were used to establish a risk assessment model of lightning disaster on the expressway net of the southern part of Jiangsu Province in which the disaster risk factors include the hazards of lightning disaster factors, the sensitivity of disaster environment, the vulnerability of hazard-affected bodies and the prevention and mitigation capacity of lightning disaster. The risk of lightning disaster on the expressway net was evaluated and the risk division was mapped. All of these works can provide a reference basis for the planning and design of expressway net, traffic operational safety and prevention and reduction of lightning disaster in China. The main conclusions of this study showed as follow:(1) In the south part of Jiangsu Province, there were more CG lightning activities in the western expressways than in the eastern expressways. The largest frequency appeared on Yangzhou-Liyang Expressway, the peak period of CG lightning activities was the period from June to August in a year, and the peak time (July) on the western expressways is earlier than the eastern region (August). But the peak time (13-16h) on the CG lightning frequency of the eastern expressways is slightly earlier than that of the western region (14-18h).(2) The CG lightning peak currents were mainly concentrated in the 20-50kA, and the peak current intensity of CG lightning on the eastern expressways is greater than that the western expressways. The high frequence regions of the CG lightning activities were the expressways in the Nanjing-Zhenjiang Hills, around the Taihu Lake, and along the Yangtze River Valley. Among them, the Expressway around Nanjing City, the Zhenjiang part of Yangzhong-Liyang Expressway, the Nanjing part of Nanjing-Hangzhou Expressway, the Wuxi part of the Expressway along Yangtze River and the Shanghai-Nanjing Expressway were the high-strength and high-frequence occurrence sections of CG lightning activity.(3) The IC lightning activities in 2013 occurred mainly from May to September. The IC lightning frequencies of the western expressways fluctuated obviously in a distribution type of double peak months and the IC lightning activities on the eastern expressways were relatively concentrated and took a distribution type of a single peak month. The time of IC lightning in the western expressway (13-18h) is earlier than in the eastern expressways (17-18h).(4) According to the formation principle of the thunder and lightning disasters and the researches of the influence factors on them, some appropriate evaluation factors were selected and a comprehensive model on the occurrence risk of the thunder and lightning disaster on the expresswas net in the south part of Jiangsu Province was established on the basis of the consideration of the hazards of lightning disaster factors, the sensitivity of disaster occurrence environment, the vulnerability of hazard-affected bodies and the prevention and mitigation capacity of lightning disaster. Consequently, the the risk of lightning disaster on the expressway net was evaluated and the risk division was mapped under the assistance of ArcGIS, a software of geographic information system.