Galina Churkina
Water is an essential element necessary for maintaining the life of various organisms on Earth. This chapter discusses how and why urbanization has such profound effects on the water cycle from a city level to the whole globe. These effects are discussed in the context of the distinct structural and functional properties of cities described in detail in Chapter 3 . This chapter begins with a description of the water cycle and its major fluxes, followed by a description of changes in major water fluxes in an urban ecosystem. These changes include water quantities and quality. Because many cities are not sourcing water locally, a host of various urban water sources is discussed thereafter. These include groundwater, surface water, recycled water, water desalination, and water imports, such as cross-basin water transfers and bottled drinks. The chapter concludes with a discussion of indirect effects of urbanization on the global water cycle, such as virtual water consumption and sea-level rise.