Inter-basin transfers as a supply option: the end of an era?

International audienceThis chapter discusses the evolving role of interbasin transfers (IBT) in urban water management. After providing an historical overview of IBT development, the chapter describes how IBTs are challenged by a change in the technological and socio-economic context. The emergence of alternative technologies, such as desalination, wastewater reclamation and reuse, or managed artificial groundwater recharge is reducing the attractiveness of IBTs. Water utilities are also becoming increasingly aware that water conservation programs can save volumes of water at a much cheaper cost than IBT. Various international examples are used to show that IBTs trigger increasing concerns from communities involved or affected, in particular related to the environmental impact on donor and receiving river basins, the economic impact on donor regions, the impact on local cultures and livelihoods, how costs and benefits are distributed (social justice), and issues related to public participation. The chapter concludes by looking ahead at new and more efficient uses of existing IBTs. As conjunctive use management approaches gain support, IBTs will be operated in conjunction with aquifer storage and recovery schemes. They will probably also support the development of emerging water markets, in particular during drought years