Sandra Postel has a post on this topic on the AWRA blog. Here is what she says:
We typically think of water “infrastructure” as the collection of dams, levees, canals, pipelines, treatment plants and other engineering works that help provide water services to society. As Gerry Galloway pointed out in the last issue of IMPACT, this infrastructure is sorely in need of maintenance and upgrading. However, another class of infrastructure needs urgent attention as well: the aquatic ecosystems that provide so many valuable, but typically unpriced, goods and services to society.
Healthy rivers, floodplains, wetlands, and forested watersheds supply much more than water and fish. When functioning well, this “eco-infrastructure” stores seasonal floodwaters, helping to lessen flood damages. It recharges ground water, filters pollutants, purifies drinking water, and delivers nutrients to coastal fisheries. Most importantly, it provides the myriad habitats that support the diversity of plants and animals that perform so much of this work and keep the planet humming. It is difficult to place a dollar value on any one piece of this eco-infrastructure, but in 2005, scientists participating in the Millennium Ecosystem Assessment estimated that wetlands alone provide services worth $200-940 billion per year.
The water strategies of the 20th Century worked largely against nature, rather than in concert with it. As a result, ecological infrastructure has been dismantled and degraded at a rapid rate. An estimated 25-55% of the world’s wetlands have been drained, 35% of global river flows are now intercepted by large dams and reservoirs, and more than 100 billion tons of nutrient-rich sediment that would otherwise have replenished deltas and coastal zones sits trapped in reservoirs. River flows are turned on and off like plumbing works, eliminating the natural flow patterns and habitats upon which myriad life forms depend.
Fortunately, forward-thinking planners, resource managers, and engineers from around the world are demonstrating that clean drinking water, flood control, and other human needs can be met in ways that use ecoinfrastructure rather than destroy it – and that such approaches often save money. For example, through watershed protection and aggressive conservation measures, cities as different as Bogotá, Colombia, and Boston, Massachusetts, have postponed construction of expensive water supply capital projects, saving their residents money while protecting critical ecosystems.
More typically, however, the benefits of capitalizing on nature’s services continue to go uncaptured. To cite just one example, following the Great Midwest Flood of 1993, U.S. researchers estimated that restoration of 13 million acres of wetlands in the upper portion of the Mississippi-Missouri watershed, at a cost of $2-3 billion, would have absorbed enough floodwater to have substantially reduced the $16 billion in flood damages. Unfortunately, instead of calling floodplains and wetlands back into active duty, officials in the region permitted even more floodplain development. According to Nicholas Pinter of Southern Illinois University in Carbondale, 28,000 new homes and 6,630 acres of commercial and industrial development have since been added on land that was under water in 1993.
Global warming and its anticipated effects on the hydrological cycle – including increased flooding, droughts, and storm intensity – will only add to the value of ecological infrastructure that helps mitigate these effects. For the same reason people buy home insurance and life insurance – to avoid catastrophic losses – societies need to buy more disaster insurance by investing in the protection and restoration of watersheds, floodplains, and wetlands.
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