A projects portfolio selection for water security addressing future increasing water demand and salinity intrusion in Zhuhai City, coastal China.

Water security is essential for sustainable economic and social development. To ensure water security, water engineering projects play an important role in regional developing program. The coastal city-Zhuhai City suffers a challenge from both future increasing water demand and salinity intrusion, To keep water security of the city, several alternative projects are designed. However, as the high cost of the projects and the potential adverse influence, a final projects portfolio, as well as their construction order has not be decided. To assist a proper decision of projects portfolio for local water security, this study proposed a combined method with one-vote veto and Analytic Hierarchy Process, to evaluate every projects portfolio from various perspectives. The results show: 1) to satisfy future water demand of 150 thousands m3/h, it is recommended to adopt a projects portfolio including expanding existing reservoirs and constructing new reservoirs, as its higher capacity utilization (96.87%), relatively lower construction and operation costs (8.59 billion and 57 million respectively), and lower ecological impact; 2) to satisfy future water demand of 160 thousands m3/h or more, transferring water from other cities should be an indispensable part for water security; 3) channel reservoir is not recommended as its high construction and operation costs, and high ecological impact. This study evaluated different alternative projects for cities' water security and provided a strong support for local government to decide their long-term projects portfolio and their construction order. The proposed method may be readily applied in other regions.