Water: An essential resource and a critical hazard

Urban water managers must provide adequate water supplies to meet growing demands for a range of water uses (including essential drinking water) whilst mitigating the negative effects of water in the wrong place, which occur at times of flood arising from extreme weather events. Many urban areas around the world are becoming increasingly water stressed, and cities such as London are developing solutions to address expected future shortages. As well as physical challenges, this chapter discusses problems of effective water governance and how decision-making across multiple scales is needed for effective water resource management—combining both technical and non-technical innovations. Current practice is characterised by many unsustainable activities, with many cities locked into a legacy of ageing infrastructure systems developed in the past. Key characteristics of more sustainable water systems are presented which represent the paradigm shift that is required in how urban water is dealt with. Features of urban water resilience are examined which can be achieved through an iterative adaptive management approach to water management. Examples are given that relate to the use of green infrastructure to achieve water-sensitive urban design, which mitigates the adverse effects of storm water at locations where the rain falls, whilst simultaneously providing a range of other benefits. Multifunctional infrastructure is described where innovative engineering can deliver more than one service from a single purpose project. The chapter concludes by stressing the need to see the urban water system as part of the wider urban fabric which positively adds to the layout, security and liveability of future cities