A game-theoretic method to optimize allocation of defensive resource to protect urban water treatment plants against physical attacks

Urban water treatment plants (WTPs) threatened by terrorist attacks is critical to residents’ security and economic development. They are treating and transit hubs that connect the upstream water sources and downstream urban distribution network. Due to the limitation of defensive resources, how to appropriately allocate defensive resources to protect WTPs against terrorist attack is still a challenging issue for urban municipal department. As of now, very few studies have investigated this problem, which often involve strategic game between the attacker and defender. This study presents a game-theoretic method and operational framework to optimize the allocation of defensive resource to protect urban WTPs against terrorist physical attacks. This method fully considers the direct economic loss, systematic loss and human loss generated by the attack on WTPs, and then model the strategic interactions between defenders and terrorists by integrating game theory with risk assessment. In the case study of typical urban water distribution network including five WTPs in central China, we figure out the optimal allocation strategy of defensive resources in Nash equilibrium using proposed game-theoretic method, and then thoroughly compare it with three conventional allocation strategies solely based on risk assessment. The results show that the resources allocation strategy and the attack strategy in Nash equilibrium are optimal strategies for both defender and attacker respectively. Furthermore, the feasibility and availability of the proposed method and operational framework in identifying the optimal allocation strategy of defensive resources is also tested and confirmed in the case study.