"There is no other engineering design, perhaps other than dams, that more directly contravenes the natural processes of a river than a levee, It divorces a river from its floodplain. One of the most dynamic systems in the world is asked to hold still when you place levees on it, "

 Dr. Jeffrey Mount author, California Rivers and Streams

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Levees can constrict a river, increasing flow velocities and causing flooding upstream and downstream

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FLAWS IN THE SYSTEM

As hydrology expert Dr. Philip Williams has pointed out, California's flood control system unfortunately contains flaws in design and operations.8 Obviously, even with the best of engineering assumptions and intentions, flooding cannot always be controlled. What the 1997 floods proved was that these systemic flaws pose serious problems to both public safety and the environment.

The trouble with levees

The old saying that 'you're only as strong as its

weakest link' is never more true than it is during a flood. Levees paralleling several thousand miles of rivers and waterways in California are the final link in the state's structural flood control system. Those dozens of levee breaks in 1997 highlighted the weaknesses in that flood protection chain.

Not only was there inadequate floodway space (the area between levees) -- which meant that some levees were simply overwhelmed by floodwaters--but poor levee construction, unreliable foundations, and being in locations too close to river banks all contributed to the numerous levee failures.

On the Feather River, near the Northern California towns of Yuba City and Marysville, some experts suggest that the disastrous floods experienced in 1986 and again in 1997 resulted from levee locations and construction techniques that ignored historic river channels and the area's rather porous and unstable gravel beds.

Reliable levees are thus a fundamental necessity for protecting vulnerable floodplains that already have been urbanized. Dam operators cannot do their jobs properly if they have poor, unreliable levees downstream. The best of reservoir operations will be rendered meaningless if that critical link in the hood protection chain is not strong enough.

Continued In Flaws In The Existing System Part II

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