How Agriculture Can Ease The Global Urban Water Shortage

A new study that looks at the water competition between cities and agriculture has found that urban water demand in 482 of the world’s largest cities will increase by 80% by 2050, leading to an acute urban surface-water deficit. However, the study also discovered that in certain instances, even a 10% increase in irrigation water-use efficiency can help to overcome urban surface-water deficits.

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Cities around the world are expanding markedly in size as global urban growth leads to more than two billion additional urban residents by 2030. Today, approximately 54% of the global population (that is, 3,9 billion people) live in cities, a percentage that is likely to grow to between 60% and 92% by the end of the 21st century, according to scenarios from shared socioeconomic pathways (SSPs). The latter are part of a framework developed by climate change researchers to analyse the impact of, and adaptation to, climate change.

Household water use has almost quadrupled over the last 60 years due to increasing population, wealth and access to drinking-water infrastructure, and there has been an even higher increase in general water use in cities. This trend will continue, with household water use forecast under one scenario to increase by another 80% by 2030.

An earlier study analysing a range of SSP scenarios estimated an increase of between 50% and 250% in global water withdrawals for domestic use by 2050.

This growth in demand comes just as cities are confronted with water-related problems caused by an increase in urban population, rising prosperity and changes in water supply, potentially leading to water shortage and groundwater over-abstraction.

GLOBAL HYDROLOGICAL MODELS TO ASSESS CHANGES IN WATER CYCLE

Climate change poses an additional risk to metropolitan areas and is likely to exacerbate the major water challenges of the future.