Spatiotemporal Impact Of Typical Marine Disasters On Traffic Operation Behavior

Frequent marine disasters seriously endanger human economic development and the safety of life and property.China is one of the countries most seriously affected by marine disasters in the world.Such disasters characterized by variety,wide distribution,high frequency and gigantic loss bring great threat to the coastal areas.In social activities,traffic operation is an important component.The safe,efficient,and stable traffic operation lays the foundation for the stable development of the social economy.Under natural disasters,smooth traffic operation is an important manifestation of the normal operation of cities and shipping.Investigating the response of social population activities during marine disasters and discovering sensitive areas are crucial to urban planning,disaster prevention and mitigation,and emergency rescue.Therefore,this article uses traffic operation behavior as the starting point to study the impact of typical disasters on the spatiotemporal dynamics of traffic activities.This paper selects two typical marine disasters,storm surges and Ulva prolifera,and explores the impact of storm surges on road traffic operations(taxi operations)and the influence of Ulva prolifera on maritime traffic operations(ship navigation).The following studies have been carried out:1)The big data analysis framework of the impact of marine disasters on traffic operation is proposed,which can effectively support the analysis of the impact of marine disasters on road and maritime traffic operation.This paper defines traffic characteristic parameters based on key trajectory elements such as traffic type,quantity,trajectory points,road network to quantitatively describe traffic operation behavior.By exploring the dynamic changes of traffic operation before and after disasters,within and outside the disaster range,this paper reveals the mechanism of marine disasters on transportation,from the two dimensions of quantity and space.It is intended to verify the following conjectures: i)different types of marine disasters may have different degrees of impact on their targets;ii)the spatial distribution of traffic operations under disasters may undergo huge changes;iii)the formation of disaster-sensitive areas is not only related to the disaster itself,it may be restricted by residents’ willingness to travel or transportation hubs.2)The temporal and spatial operation parameters of urban taxi affected by typhoon disaster are constructed,and the negative influence of tide level and taxi service distance and area is revealed.Based on the typhoon dynamic trajectory,this paper defines a parameter—the distance to typhoon affected areas,which is used to quantitatively describe the dynamic spatial relationship between the taxi trajectory and storm surges.Using 3 storm surge parameters(intensity,tide level,distance from typhoon influence range)and 4 taxi parameters(the number of orders,service distance,service area,the spatial dynamics of the origin and destination matrix),the paper figure out the changing rules during 14 typhoons,and calculates the correlation.It is found that the storm surge does cause the rise of coastal tide level,and the closer the distance is,the greater the rise of tide level;and there is a potential negative correlation between the tide level and taxi service distance and area.Using the fluctuation degree of taxi service area to locate disaster sensitive areas of Shenzhen,this paper finds that sensitive areas are mainly located at the boundary between the central urban area and other districts of Shenzhen.They are constrained by the dynamic changes in the origins and destinations.And 80% of the important transport hubs(bus stations,railway stations,airports)are located in sensitive areas.3)This paper analyzes the impact of Ulva prolifera on the operation of marine ships,and effectively identifies the sensitive areas.Based on the recognition of MODIS images,the distribution and coverage of disasters in 2014 are extracted.To reveal the evolution of Ulva prolifera,the area and density are calculated,the migration path is extracted,and the disaster life cycle was divided.In addition,two parameters of ship operation behavior(speed,course)are used to explore the changes in the numerical distribution pattern of traffic trajectory within and outside the disaster range,and further calculate the correlation.It is found that the distribution of Ulva prolifera has indeed caused the instability of ship speed and direction,and density is the main cause.Using spatial distribution of abnormal trajectories of ships to locate disaster sensitive areas,this paper finds that sensitive areas of Ulva prolifera in the Yellow Sea are distributed in the sea area between Jiangsu and Shandong,and the long-term dense distribution of Ulva prolifera is the main reason for their formation.It is worth noting that the sensitive areas along the coastline are related to the ports(Qingdao,Rizhao and Lianyungang)along the coast.