A bi-level humanitarian response plan design model considering equity and efficiency—the example of Yemen

Yemen has suffered from a civil war since 2015, which caused the largest famine in the world at this time. People came in need of urgent humanitarian relief in all sectors. In this situation, the donor countries are offering funds to non-profit humanitarian organizations to help Yemen in critical sectors, such as food, health, water, education and other sectors. We propose a new bi-level optimization distribution model for large-scale emergency logistics in Yemen. The upper-level model aims to minimize the unmet demand. The lower-level model seeks to maximize the funds sent to affected areas that fulfill the needs of the affected people by appealing to the donor countries to increase the funds. This model ensures a satisfying rate of equity and efficiency distribution among aid recipients of all governorates of Yemen based on their needs. We consider in this work the top ten donor countries, the nine sectors of the sustainable development goals, the five top humanitarian organizations and twenty-two disastrous regions. The model is applied and validated using actual data collected from Yemen in 2021. The results indicate the necessity of redistributing funds to all governorates of Yemen according to their needs and the priority of the supporting sectors. This proposed model is essential to humanitarian relief decision-makers in general and workers in Yemen in particular as it ensures the continuous flow of aid from donors to beneficiaries and is equitable and effectively distributed. It also gives a glimpse of the importance of continuing to appeal for fundraising from the donors to increase funds and their importance to cover the most significant percentage of those affected.