by Peter H. Gleick
Huffington Post (2/9/2018)
Cape Town is parched. Severe drought and high water use have collided in South Africa’s second largest city, and unless the drought breaks, residents may run out of water in the next few months when there simply isn’t enough water left to supply the drinking water taps.
In response to this looming “Day Zero” currently projected in May? city managers have imposed new and unprecedented restrictions, including limiting residential water use to 50 liters (around 13 gallons) per person per day. They released plans to open 200 community water points to provide emergency water in the event of a shutoff – for four million people. As the crisis worsens, water scarcity will sharpen South Africa’s economic inequalities, inflaming tensions between wealthier and disadvantaged communities.
Cape Town is not alone. Water crises are getting worse all over the world. The past few years have seen more and more extreme droughts and floods around the globe. California just endured the worst five-year drought on record, followed by the wettest year on record. São Paulo, Brazil, recently suffered a severe drought that drastically cut water supplies to its 12 million inhabitants – a drought that also ended in heavy rainfall, which caused extreme flooding. Houston was devastated in 2017 by Hurricane Harvey, the most extreme precipitation event to hit any major city in the United States.
Severe droughts and floods. Water rationing. Economic and political disruption. Urban taps running dry. Is this the future of water?
Any city, in building a water system, tries to prepare for extreme weather, including floods and droughts. It also considers estimates of future population growth, projections of water use and a host of other factors. Cape Town’s water system is a relatively sophisticated one, with six major storage reservoirs, pipelines, water treatment plants and an extensive distribution network. Its water managers, and South Africa’s overall water expertise, are among the best in the world.
The problem is that the traditional approach for building and managing water systems rests on two key assumptions. The first is that there is always more supply to be found, somewhere, to satisfy growing populations and growing water demand. The second is that the climate isn’t changing.
Neither of these assumptions is true any longer.
Many regions of the world, as in Cape Town, have reached “peak water” limits and find their traditional sources tapped out. Many rivers are dammed and diverted to the point that they no longer reach the sea. Groundwater is over pumped at rates faster than nature can replenish. And massive long-distance transfers of water from other watersheds are increasingly controversial because of high costs, environmental damages and political disagreements.
Peter H. Gleick is a climate and water scientist, co-author of The World’s Water, and a member of the U.S. National Academy of Sciences.