”FLOODS AND DREDGING”

For the time being there are floods in Thailand and Cambodia (and probably many other places). The floods are now threatening Bangkok. Hundreds of people have succumbed to the high waters.

Floods are a returning phenomenon. They have occurred for thousands of years. They will do so in the future. Not too much to do about that.

Or is it? Atle watches the rain falling from the clouds – pure, clean water. Atle watches the water as it trickles downwards in fields, roads, wherever. The water is muddy, where does the mud come from, where does it go?

Atle had a small pond before. After every rainfall the water in the pond changed to the colour brown. He did not take care. By and by there was more mud and less water in the pond. Eventually he had to do some dredging to restore the pond to what it looked like years ago.

Every year rivers and water reservoirs are filled with sediments originating from fields, forests and mountains. Many navigable rivers are completely changed after floods. Sand banks grow up where the waters were deep last year.

To keep rivers and harbours navigable some dredging have to be done from time to time.

Why not dredge river beds, lakes, and water reservoirs on a regular basis to prevent excessive floods? The sediments can be used for many purposes, even profitable purposes.

In China quite a few major rivers have river beds excceding the flatlands around due to dike building over hundreds of years. This has caused disastrous floods with millions of people dead. (See http://en.wikipedia.org/wiki/1887_Yellow_River_flood and http://en.wikipedia.org/wiki/1931_China_floods )

That dredging might be a good solution is shown by this: ”On 19 June: the Yellow River Flood Control and Drought Relief Headquarters launched a 20-day operation to discharge water from three reservoirs (held back by the Wanjiazhai Dam, Sanmenxia Dam and Xiaolangdi Dams) in a bid to clear sediment in the river.^[20]”  See http://en.wikipedia.org/wiki/2011_China_floods  - With this solution the sediments are only transported downstream – they are not taken away for the riverbed.

Atle’s advice about DREDGING is for free.

Decreasing the impact of floods is a way of investing money in infrastructure – the profits are difficult to measure but will probably surpass the profits of other investments.Not to forget all the lives that will be saved.