Research On Resilience Of Oil Spill Rescue Network In Chongqing Section Of Yangtze River Trunk Based On CML

The prevention and emergency response of ship oil spills has always been one of the key contents of water traffic safety and ship pollution prevention and control work.However,due to its more complex hydrological conditions and navigation environment,the Yangtze River Basin has a dense population and fragile ecological environment along the coast.Once an oil spill accident occurs,it will be more difficult to complete emergency disposal work.Therefore,in order to further evaluate and improve the emergency coordination ability of ship oil spill accidents in the Chongqing section of the Yangtze River main line,it is necessary to establish a mutually dependent and supportive emergency rescue network based on a systematic perspective to characterize,evaluate and even optimize the operation and maintenance capability of the water area.Therefore,this thesis constructs a multi-element heterogeneous interdependent network model for the Chongqing section of the Yangtze River based on the theory of dependent networks,and proposes an improved coupled map lattice(CML)model to describe and predict the cascading failure dynamic process of the network under discrete time variables.Then,through structural entropy,density entropy,oil spill equivalent disposal capacity and survival node ratio,this oil spill rescue network is identified and evaluated for its vulnerability and resilience under different scenarios.Firstly,the improved CML model is disassembled and simulated with the original model,the model considering the intensification coefficient and the improved model considering both the intensification coefficient and resistance coefficient under the continuous random disturbance of a wide range.The coupling coefficient,structural entropy,density entropy and two additional coefficients are compared and analyzed for their performance and role in the network.The results show that the improved CML model can consider the coupling effect of node and subnet attributes in cascading failure more comprehensively,then make the simulation results more realistic.Secondly,the cascading failure characteristics of oil spill rescue networks under ship accident risk disturbance and channel oil spill expected disturbance are compared and analyzed.The results show that load dissipation capacity and response and support capacity between nodes are key factors determining the stability and resilience of multielement heterogeneous networks.Although large-scale hazardous chemical terminals and emergency resource equipment depots are high-intensity and high-resistance nodes that are not easily affected,when the navigation conditions are gradually restricted due to multiple small disturbances leading to ship load accumulation,rescue forces will be unable to reach the scene through water transportation to play a role,eventually leading to network collapse.Finally,different intensities of intentional attacks are compared to analyze their impact on the operation and maintenance status of rescue networks under different scenarios.It is found that rescue networks exhibit higher fragility and sensitivity under this attack mode;when facing attack disturbances,channel subnets are more susceptible to influence than other subnets,and their sensitivity is positively correlated with ship navigation density.Once fixed resource nodes that are not easily affected and mobile rescue nodes fail,more serious cascading failure consequences will occur,which will greatly increase the probability of network collapse.In addition,it is impossible to obtain qualitative changes by only optimizing network topology or increasing its coupling coefficient.The professional quality and rescue quality of rescue teams and local rescue facilities should be strengthened at the same time.