A Location Problem of Two-Level Disaster Relief Facilities for Vulnerable Networks

There has been increasing focus on disaster management and logistics due to the frequent occurrence of disasters, seeking to respond to disaster impact in a more effective manner in terms of delivering relief and rescue. Emergency response can be challenging for some vulnerable networks with low road density and subject to a high probability of being disconnected by disaster impact. Once some roads of such networks are damaged, it is likely that some locations or sub-areas will become isolated from outer supplies. This research formulates a location problem of disaster response facilities at two levels: disaster response centers and secondary facilities, self-sustainable relief stations. The former collects relief materials and re-distribute them to the affected areas; the latter ensures the self-sustainability of residents, even though they are isolated. The locations of the two facilities are interdependent based on the network structure and connectivity. Thereby, a bi-level programming approach is developed to integrate determination of the locations at each level and address the associated complexity due to the interdependency. In addition, a heuristic algorithm to calculate connectivity reliabilities is developed with the correlation between the roads. Numerical experiments are made using the network of Nantou County in Taiwan, a mountainous county which is vulnerable to frequent landslides caused by earthquakes, hurricanes and heavy rainfalls. Experiment results show that the deployment of two-level disaster response facilities enables more efficient allocation of limited resources and reduce the expected number of unsupplied people during emergency response, which highlights the practicability of the proposed approach.