About one third of the urban population ( about 1.693–2.373 billion people) will face water scarcity in 2050 with India projected to be most severely affected, according to a new study published in Journal Nature.
The study “Future global urban water scarcity and potential solutions” notes that urbanization and climate change together exacerbate water scarcity. The study shows that the number of large cities exposed to water scarcity is projected to increase from 193 to about 284, which also includes ten to 20 megacities.
The study points out that about 933 million urban residents lived in water scarce regions in 2016 with 359 million and 573 million experiencing perennial and seasonal water scarcity respectively. Of the 526 large cities (population greater than one million), 193 cites were located in water-scarce regions.
With respect to 30 megacities across the globe (population over ten million), the study says nine were located in water-scarce regions. Among them Los Angeles, Lahore, Moscow, Bangalore, Delhi and Beijing were located in regions with perennial water scarcity and Mexico City, Istanbul and Karachi in seasonally water-scarce.
FACTORS INFLUENCING URBAN SCARCITY
- Growth in urban population and water demand
- From 2016 to 2050, population growth, urbanization, and socioeconomic development projected to increase water demand and contribute to an additional 0.990 (0.829–1.135) billion people facing urban scarcity of water, accounting for 87.5% (80.4–91.4%) of the total increase.
- Climate change projected to alter water availability and increase the urban population subject to scarcity of water by 52 million, accounting for 4.6 per cent of the total increase.
The study shows that 95 per cent of water scarce cities could find at least one potential solution, but they need substantial investment and solutions. The aggravation of global urban water scarcity and the consequences of potential solutions will challenge the achievement of several SDGs. Therefore, there is an urgent need to further improve water-use efficiency, control urbanization in water-scarce areas, mitigate water availability decline due to climate change, and undertake integrated sustainability analyses of potential solutions to address urban water scarcity and promote sustainable development, the study notes.
The study points out that about 260 cities have the option of implementing two or more measures. For example, they say that Los Angeles can adopt desalination, groundwater exploitation, inter-basin water transfer, and/or virtual water trade. However, the study further writes that 16 large cities, including two megacities (Delhi and Lahore) are restricted by geography and economic development levels, making it difficult to adopt any of the potential water scarcity solutions.
Noting that domestic virtual water trade was the most effective solution, the study says it could alleviate scarcity of water for 208 large cities, which includes 14 megacities.
Some other ways;
- Inter-basin water transfer could be effective for 200 large cities, including 14 megacities
- Groundwater exploitation could be effective for 192 large cities, including 11 megacities
- International water transfer and virtual water trade good for 190 large cities, including 10 megacities
- Reservoir construction could relieve scarcity of water for 151 large cities, including 10 megacities.
- Seawater desalination has the potential to relieve scarcity of water for 146 large cities, including 12 megacities.
- Water-use efficiency improvements, slowed population growth rate