Sandra Postel is director of the Global Water Policy Project in Amherst, Massachusetts, and author of Liquid Assets: The Critical Need to Safeguard Freshwater Ecosystems , released this week by the Worldwatch Institute.
It may be tempting to pass off the world’s mounting water woes—from droughts and floods to dried-up rivers and shrinking lakes—to the whims of nature. But water calamities are increasingly of human origin, the consequences of policies and projects that encourage waste and inefficiency and that work against nature’s water cycles rather than with them.
The good news is that by taking advantage of the work that healthy watersheds and freshwater ecosystems perform naturally, cities and rural areas can purify drinking water, alleviate hunger, mitigate flood damages and meet other societal goals at a fraction of the cost of conventional technological alternatives. But because commercial markets rarely put a price on these “ecosystem services,” and because governments around the world are failing to protect them, they are being lost at a rapid rate. It almost seems as if the point of public policy is to liquidate the earth’s water assets like a store going out of business.
Rivers, lakes, wetlands and other freshwater ecosystems provide a host of benefits to society. In addition to supplying water and fish, they store seasonal floodwaters, helping to lessen flood damages. They recharge groundwater supplies, which can ensure that water is available during dry spells. They filter pollutants and purify drinking water. And they provide the diverse habitats that support the myriad species performing much of this ecological work.
The water strategies of the 20th century were dominated by large dams, levees, river diversions and other big engineering projects. These strategies helped provide much of the world with drinking water, food, electricity and flood control. But they also disrupted the functioning of aquatic ecosystems on a vast scale. Today, dams and reservoirs intercept about 35 percent of river flows as they head toward the sea—up from 5 percent in 1950. Many overtapped rivers no longer reach the sea for extended periods of time, decimating deltaic fisheries and coastal zones from which millions of people on the economic fringe make their living. Meanwhile the loss of wetlands, floodplains and forested watersheds is increasing the economic and human toll of floods and other natural disasters, a toll almost certain to increase as global warming intensifies the hydrological cycle.
Meeting new water needs requires a different approach. Fortunately, forward-thinking cities, villages and farming regions around the world are demonstrating that drinking water, food security and flood control needs can be met in ways that employ—rather than destroy—ecosystem services. Many are saving their residents a great deal of money by doing so, while creating healthier environments at the same time.
A variety of municipalities are realizing, for example, that healthy watersheds are nature’s water factories and that it pays to protect them. More than half a dozen U.S. cities have avoided the construction of expensive filtration plants by protecting their watersheds. Working in partnership with towns, businesses and community groups in the Catskills-Delaware watershed, New York City is investing $1.5 billion in watershed measures over 10 years to avoid a filtration plant estimated to cost $6 billion to build and $300 million per year to operate.
Bogotá, Colombia and Boston, Mass., have coupled watershed protection with effective conservation efforts, reducing capital expenditures and safeguarding ecosystem services. Bogotá’s conservation success has delayed the need to construct new water supply facilities for at least 20 years. Water use in the greater Boston area hit a 50-year low in 2004, following an aggressive conservation program begun in the late 1980s that has indefinitely postponed construction of a diversion from the Connecticut River and saved residents more than $500 million in capital expenditures alone.
Strategies that value and protect watersheds, wetlands and floodplains are also critical to reducing hunger, which now saps the health and energy of 852 million people, most of whom live in poor farming regions. Rainwater harvesting methods coupled with affordable small-plot irrigation technologies are enabling poor farmers to boost their crop production by using local water supplies more effectively. Better management of soils, water and nutrients has quadrupled irrigated rice yields in parts of Madagascar, while also saving water. And researchers studying an extensive floodplain in northeastern Nigeria found that the net economic benefits of direct use of the floodplain—for agriculture, fuelwood and fishing—exceeded by 60-fold those of an upstream irrigation project that would destroy much of the floodplain.
Healthy ecosystems provide valuable insurance against catastrophic losses from flooding and other natural disasters as well. Nearly 5,000 Haitians lost their lives and tens of thousands lost their homes during tropical storms in 2004. Although tagged as natural disasters, these tragedies were exacerbated by the clearing of trees in the Haitian highlands, which left sloping lands susceptible to rapid flood runoff and massive mudslides. The same storms that devastated Haiti caused far less damage in neighboring Puerto Rico, where highland watersheds are mostly forested.
For the same reason people buy home insurance and life insurance—to avoid catastrophic losses—societies need to “buy” disaster insurance by investing in the protection of watersheds, floodplains and wetlands. Global warming and its anticipated effects on the hydrological cycle will make the robustness and resilience of nature’s way of mitigating disasters all the more important, as tropical storms, spring flooding and seasonal droughts increase in frequency and intensity.
Governments need to overhaul water policies and practices in a way that will protect freshwater ecosystems and their valuable services. High priorities include requiring drinking water suppliers to invest in watershed protection and establishing caps on the degree to which human activities modify river flows, deplete groundwater and degrade watersheds. Combined with more effective water pricing, these caps will encourage conservation and drive up water productivity—the unit value of water extracted from nature—and leave more water in place to do its ecological work.
Old approaches and entrenched ways die hard. But the benefits of workiing constructively with nature’s water cycle, rather than further disrupting it, are now too compelling to ignore.
