The Research On The Meteorological Risk Of Railway System Over The Sichuan-Tibet Region

Traffic and weather have a very close relationship.Specifically the railway system is a highly sensitive to meteorological disasters.The orographic characteristics in Sichuan and Tibet are highly complex due to the sharp variation of elevation,unevenly distributed meteorological elements and the low density of meteorological observatory network,leading to difficulties in studying the associated climate background and meteorological disasters.As the data supporting the railway construction and operation is insufficiently achieved,it is of importance to investigate the characteristics of meteorological elements affecting the railway system in Sichuan-Tibet region and comprehensively analyze the associated meteorological risk.In this study,the temporal and spatial distribution characteristics of meteorological elements in Sichuan-Tibet region are first analyzed.Then,the meteorological factors related to the railway rational planning and operation are investigated across the areas where the railway system is sensitive to meteorological disasters.This analysis will be based on China's surface climate standard values and the data of the spatio-temporal multi-scale analysis system STMAS(Space-Time Multiscale Analysis System).Lastly the layout of the station network along the railway in Sichuan-Tibet region is suggested based on the investigated meteorological factors..The results suggested the necessity of promoting the prevention and mitigation of thunderstorms,short-term heavy rainfall,and thunderstorms in the eastern part of the Sichuan-Tibet region.For the central region,strong winds,temperature diurnal range,low temperature and frozen soil should be focused.Moreover,the prevention and mitigation of strong winds,snow,temperature diurnal range,low temperature and frozen soil should be enhanced.The result also indicates an increasing trend in the observed wind speed in the Sichuan-Tibet region,implying an increase in the meteorological risk,which is worth to be further investigated.For the route planning,the northern areas,including Lhasa,Nagqu,Xigaze,and Ganzi Prefecture,of Sichuan show relatively high comprehensive risk index,which need to be prevented.The high slope areas across the western Sichuan Plateau is sensitive to variables including the daily maximum precipitation and the lightning density index,which needs further attention during the operational stages.The results also suggested relatively high sensitivity to cross-wind over the south of Lhasa,the west of Linzhi,the east of Changdu and the Yajiang and Kangding areas of Ganzi,based on the wind rose diagram analysis using the historical data of six selected observatories.Due to the negative correlation between the wind correlation threshold and the representative range,higher density of the observatories is needed at the entrances of railway tunnels.Currently,there are three representative stations for temperature monitoring located in the Sichuan Basin,the western Sichuan Plateau and the high slope areas in the Nyingchi region.However,according to the sensitivity assessment,31 stations are required to be added for sufficiently monitoring the sensitive areas,including three stations in Chengdu for monitoring heavy precipitation and 28 stations across Ganzi and Lhasa for monitoring high winds.