If the definition of insanity is making the same mistakes over and over, then many cities have taken a certifiable approach to securing their water supplies -- and they need some radical therapy before taking the big economic, ecological, and human hits that come with a permanent state of thirst.
That’s the conclusion from a new study in the journal Water Policy, whose authors compared the water supply histories of four cities -- San Diego, Phoenix, San Antonio, and Adelaide, Australia. Among the lessons learned? Urban water conservation, recycling, and desalination aren't silver bullets. In fact, the best solution may lie upstream with farmers -- saving just 5-10 percent of agricultural irrigation in upstream watersheds could satisfy a city’s entire water needs.
But the time to act is now, argues Brian Richter, a senior freshwater scientist at The Nature Conservancy and the study’s lead author -- he says a global urban water crisis is already here. Below, Richter tells us more about what cities need to do to say on the right side of dry.
Q. Many cities take a similar pattern of water development, according to your research -- going from exhausting local surface and groundwater supplies to importing water to implementing water conservation to finally recycling water or desalination. Why is this pattern unsustainable?
A. When we overuse a freshwater source, we set ourselves up for disaster. Each of the cities we reviewed in our study has contributed to the drying of a major river or important groundwater spring. That has obvious ecological impacts and social consequences -- it affects livelihoods and human health by compromising fish production, concentrating pollution, or curtailing recreational activities.
Our research is revealing that water scarcity also causes severe economic losses by limiting or disrupting agricultural, industrial, and energy production. Texas lost nearly $8 billion in agriculture last year due to water shortages; electricity generation from hydropower dams on the Colorado River in 2010 dropped by 20 percent due to water shortages. Some estimates suggest that China may be losing $39 billion each year due to crop damage and lessened industrial production, and hundreds of thousands of people around the globe are being forced to move due to water shortages.
Because these impacts are so pervasive and damaging, we need to begin investing in water supply approaches that don’t just minimize these adverse impacts but instead begin to reverse them.