Mother Nature to the Rescue

January 16, 1995|By EDWARD FLATTAU

WASHINGTON — Washington. -- Suburban sprawl emanates from urban cores and engulfs prime farmland, forests, marshes and other open space that would better serve society in undeveloped condition. But help is on the way, and from an unexpected source: Mother Nature is coming to the rescue.

Consider Northern Virginia's Loudon County. Its local government has done little to resist the pressures to develop predominantly rural land on the edge of an urbanized metropolitan Washington region. But what political muscle could not achieve may be accomplished by considerations of water supply, or more precisely, water shortage.

A cap on runaway sprawl in the rural portion of the county is imminent because of the discovery that the ground-water table upon which most of the residents depend is being rapidly depleted. Individual wells are the source of fresh water for most Loudon inhabitants, and there is no feasible nearby outlet to serve as a future source of a municipal water supply.

On a larger scale, a similar scenario is beginning to play out in the state of Florida.

Lack of a reliable supply of potable water has slowed the issuance of permits for the building of subdivisions in certain areas. The prospect of unsustainable use of water appears to be all that stands in the way of Florida's ultimately destroying what natural beauty remains outside protected publicly or privately owned sanctuaries.

To hear water mentioned as an inhibiting factor to developmental expansion often elicits surprise. Most people regard fresh water as a renewable resource, but many fail to realize it's a finite one as well. The fact that 70 percent of the earth's surface is covered by water obscures the reality that the fresh water that sustains our existence is in much more limited abundance.

The statistics are startling. Of all the water on earth (the total of which is finite since it doesn't increase or decrease), only 2 1/2 percent is fresh -- that is, fit for human use. The rest is saline. Furthermore, less than 1 percent of all the fresh water is replenished by nature each year, essentially through precipitation that falls into the earth's lakes, rivers and streams and isn't lost to evaporation.

And not all of this is available for human use. More than half is swept up by flood waters and flows unused into the oceans. Approximately one-eighth falls in areas too remote to be reached by humans, and a substantial amount is absorbed by natural ecosystems bordering fresh-water bodies.

The bulk of the fresh water is locked up in polar ice caps and mountain glaciers (69 percent) or underground aquifers (30 percent). And while some of the latter can be feasibly tapped for human use, these aquifers take centuries, perhaps even millenniums to recharge, making the use of them a relatively brief, and obviously unsustainable respite.

As put graphically by the Washington-based World Resources Institute, ''If all the world's water fit into a bathtub, the portion of it that could be used sustainably in any given year would barely fill a teaspoon.''

So the supply is limited, yet the demand for fresh water has quintupled in the last half-century due to the human population explosion. Continuation of this rate of increase in demand cannot be sustained over the next 50 years, especially in regions that are arid to begin with.

What can we do? In the short term, intensified recycling of water and vastly improved efficiency in its use, particularly in agriculture, should be able to avert any imminent crisis. The long-range solution is obvious. Human population must be stabilized at a level that doesn't overtax available renewable fresh-water supplies.

Water availability has already served as an incentive for reducing development in some regions. Eventually it will surely do the same for family size across the entire world.

Edward Flattau writes on environmental matters.

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