City lets water have its way -- right through downtown park

Like Noah, people in Scottsdale, Ariz., knew enough to expect floods. The Indian Bend Wash, a major flood plain, runs right through the center of their city.

But building an ark didn't seem feasible - and unlike Noah, residents weren't given instructions on how to handle the problem. A plan proposed by the US Army Corps of Engineers called for a concrete drainage ditch, seven miles long and forty feet deep, running right through the city.

''We felt that ditch would be a physical and psychological divider to the community,'' says David Matthews, Scottsdale's public information officer. So the city sought help from a engineering firm.

The result is the ''Scottsdale Greenbelt,'' a seven-mile-long, grass-lined channel, which, according to Mr. Matthews, ''unites the city.'' The US Army Corps of Engineers supported the idea, took over construction of the project, and provided nearly half the funding. The project, first proposed in the '60s, is just now being completed.

The Greenbelt contains five city parks with a variety of recreational activities: golf courses, bike paths, tennis courts, lakes, swimming pools, and ball fields.

But the Greenbelt is first and foremost a means of flood control. The tennis courts are flood-proof, and are designed not to obstruct the flow of flood water. Special grasses with deep root systems were planted to control erosion. And tree planting must have government approval.

How does the Greenbelt perform?

''Beautifully,'' says Matthews. The city recently had a ''500-year flood'' - one which statistically should occur only once every 500 years. Says Matthews, ''the Greenbelt worked like a dream.''