Friday, March 23, 2012

Uncollapsible Bridges And Disaster Risk Reduction

My family used to live in a remote area. Their land was across a creek that was sedate most of the year. During flood season the creek was a raging torrent.

They requested that a bridge be built for easier access to the road. The county answered the request with a bridge that would not collapse during flood season. The bridge was high above the normal water flow and even above the height of the water during most floods. You had to climb up to it. 

It was a small bridge, made only for foot traffic. It was made only of cables. There were a couple of cables to hold onto. Your feet were on another cable. There was not much to block large objects that came whizzing down the river in extreme floods. Whatever came through, just went right through the bridge. Even if the bridge was destroyed it was easily replaceable and would not cost much to replace.

I read a long time ago about a bridge that was built out in the desert. There was a situation that was similar to the one with my parent's bridge. 

Most of the time the river in the desert was a lazy muddy stream. During the flood season it swelled to an enormous raging torrent that swept large boulders and smaller debris with it.

The bridge that was built across that river was uncollapsible. It spanned the river only when it was not flooding. During floods the bridge just sat out in the middle of the river, submerged. The raging waters rushed right over the bridge until the floods were gone. Once the floods were gone the bridge appeared again.

The bridge was not usable during flood season, but people would not be able to use whatever else might have been built anyway. If a more traditional bridge had been built to span the river during flood times, it would have had a short life. A boulder or several would have wrecked it during the next flood. The way the bridge was built only for non flood times, gave people a bridge when there was no flood and did not get destroyed.

Both of those bridges were a form of disaster risk reduction. Sometimes people have done disaster risk reduction without ever even using the term. It is a good way to use money. The money goes farther and does not have to be wasted cleaning up the same disaster over and over. I wish we would do a lot more of this kind of thinking and act on it. I am sure the world will be better for it.

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