Green Cities: A Water-Secure Future
Figure 5.1
km2, 154 basin/regions
4,500
Industry
Forecast Water Shortage for 2030
6,906 2.0%
Domestic
223
843
1,531
2,765
-40% 4,200
600 688
Groundwater
800
4,531 Agriculture
3,534
3,100
2005 demand
2030 demand
Basins with deficits
Surface water
Naturally renewed, available supply
Note: The analysis determined that today’s naturally renewable and available supply is about 4,200 cubic kilometers (km3), being about 16% groundwater and 84% surface water. Based on the demand of the domestic (or municipal), industrial, and agriculture sectors, demand of about 6,906 km3 in 2030 would outstrip supply by that year. This shortfall of approximately 2,765 km3 is known as the “supply gap.” Source: 2030 Water Resources Group (2009).
Not Just About Quantity Many regions face challenges regarding declining availability of freshwater. For example, while Asia accounts for only 36% of the world’s total water supply, Asia and the Pacific is home to more than 60% of the world’s population. Furthermore, approximately 477 million people in the region have no access to safe water, and 1.8 billion people have no access to improved sanitation facilities whatsoever (WHO/UNICEF Joint Monitoring Programme for Water Supply and Sanitation 2010). Freshwater is thus a limited resource, and one that is declining in volume in many regions because of various factors. Its availability is also increasingly threatened by rapid population growth, expanding industrial and agricultural activity, growth of urban areas, and climate change, the latter threatening to alter hydrologic cycles in major ways. As cities grow in linear terms, the amount of waste they generate grows exponentially. Thus, rather than being simply an unsightly inconvenience, pollution depreciates property values, discourages economic development, negatively impacts health and productivity, raises municipal bills (and taxes), contaminates drinking water, spoils the water used to provide numerous urban amenities, and creates countless other hazards. Despite these