Abstract:

In recent years， various emergencies and natural disasters have occurred with alarming frequency， endangering the lives and property of the general public. In China， the government assumes the role of primary responder to disasters， bearing the significant responsibility of expeditiously dispatching supplies to affected regions. This requires the government to reserve sufficient emergency supplies before a disaster occurs in order to be prepared for potential crises. However， the government’s stockpiling capacity is limited， making it difficult to independently meet the surge in demand for emergency supplies triggered by a disaster. Additionally， in the event that no emergency occurs during the stockpiling period， the government may be compelled to dispose of its stockpile at salvage value， which would undoubtedly increase the government’s financial burden.To mitigate the risks and costs associated with sole government stockpiling， existing studies have proposed a joint stockpiling model between the government and manufacturers. This model leverages the strengths of social enterprises in material management while reducing the risks associated with government stockpiling. Concurrently， in order to reduce the risks and costs associated with stockpiling， manufacturers can also adopt a combination of physical stockpiling and capacity stockpiling， whereby some emergency supplies are stockpiled as reserved capacity and produced only when needed. This approach reduces the manufacturers’ stockpiling risk and cost without significantly delaying the delivery of emergency supplies post-disaster. However， the COVID-19 pandemic highlighted challenges such as the sharp increase in the price of meltblown nonwoven fabric， a key raw material for masks. During the crisis， the price surged from 18，000 yuan to 29，000 yuan per ton， an increase of 61.11%， which undeniably raised the conversion costs for mask manufacturers. To address this issue， an innovative three-tier joint reserve model is proposed that includes suppliers’ raw material reserves. This model is designed to mitigate the problem of raw material shortages and price increases post-disaster.A two-tier joint stockpiling model between the government and manufacturers is constructed based on a quantity flexibility contract as a baseline. Then， the supplier’s raw material stockpiling is integrated into the model， which is the main research model of this paper. The optimal stockpiling quantities and the respective profit and cost for each decision-maker are derived using the inverse solving method. The results of the study indicate that （1） the probability of a disaster is the most critical factor in determining whether the government initiates emergency stockpiling； （2） for materials with prices likely to fluctuate significantly post-disaster， the government should increase stockpiling before the disaster； （3） from an economic standpoint， there is an optimization interval that can improve the profit of manufacturers and suppliers while simultaneously reducing the cost of the government in the three-tier emergency stockpile supply chain； （4） the three-tier stockpiling strategy may not always be the optimal choice， so the government should flexibly adjust the strategy according to the option price between manufacturers and suppliers. Should the option price be higher， the government should adopt the new three-tier stockpiling strategy； otherwise， it should maintain the original two-tier stockpiling strategy. Theoretical guidance for the establishment of a three-tier joint stockpiling cooperative relationship between the government and enterprises is provided in this study.

Key words: emergency supplies, production capacity reserve, quantity flexibility contract, option contract, raw material reserve