Balancing effectiveness and equity in the face of uncertainty: The case of humanitarian lateral transshipments

In humanitarian operations, decision makers must allocate limited resources efficiently while ensuring fair outcomes for disaster-affected communities. This paper addresses the Humanitarian Transshipment Problem (HTP), which involves the joint optimization of pre-positioned inventory and post-disaster lateral transshipments. The central challenge lies in balancing effectiveness, namely, the extent to which needs are met, and equity, namely, the fairness of aid distribution. This trade-off becomes even more complex under uncertainty, when multiple disaster scenarios must be anticipated. Existing approaches to this balance in stochastic settings often rely on ad-hoc formulations, offering little justification for how social welfare should be measured across scenarios. We propose an alternative framework that establishes an axiomatic foundation for evaluating the effectiveness–equity trade-off under uncertainty, filling a significant gap in the literature. Our formulation preserves desirable properties across scenarios while remaining tractable and interpretable, making it suitable for humanitarian decision-making. Using both real-world and synthetic data, we demonstrate that our model enhances system performance and supports equitable decision-making under uncertainty. Our results highlight the strategic value of lateral transshipments, especially under tight budgets and high uncertainty, and provide guidance for organizations seeking to improve fairness, effectiveness, and efficiency in disaster preparedness.