Resilient relief supply planning using an integrated procurement-warehousing model under supply disruption

In order to mitigate the damage caused by natural disasters, appropriate relief supply planning is essential for humanitarian relief chains. This paper develops a resilient relief supply plan by formulating a novel integrated procurement-warehousing model under supply disruption via utilizing a portfolio of long-term contracts between a relief organization, multiple main and backup suppliers, and a third party who provides warehousing service. By using a portfolio of supply sources, a tailored two-stage scenario-based stochastic programming model is presented for determining an integrated relief procurement-warehousing plan. The plan includes (1) a number of multi-period quantity flexibility contracts with the main suppliers at pre-disaster, for prepositioning of relief supplies while ensuring to receive extra required amounts at post-disaster, (2) a number of dynamic option contracts with backup suppliers for decreasing the impacts of risks pertaining to the demand uncertainty and supply disruption at the main suppliers, and (3) a multi-period warehousing contract with a third party which allows the relief organization to adjust the required storage space in different periods to avoid extra cost pertaining to the storage space surplus/shortage. An effective differential evolution (DE) solution algorithm is also devised to solve the real scale instances efficiently. Applicability of the proposed model is illustrated by a real case study and useful managerial insights are extracted through conducting several sensitivity analyses.