A river changing course (and should it?)

When I was little, I was fascinated by a storybook about a family living by a river. One day, the grandmother told her grandson that the river god had been angry in the past, throwing earth, trees, houses and people across the banks. The boy asked his father later that day about what grandma told, and his father explained to him that was a natural phenomenon when a river changed its course.

I wondered how it would look in real life.

Last week, while I was reading a textbook, the phrase “river changing course” came up, which reminded me about the childhood story. Curious, I looked the phrase up and found this gif from reddit

Time lapse of a river changing course

Now isn’t that breathtaking? This whole thing only takes place in less than 30 years. This is what a river does without human intervention.

From the hint “Reserva comunal El Sira” in the top left corner, I was able to locate this place – the Ucayali river in Peru. You see, the river is still meandering and doing what a river does to this day.

Now, what happens if people live along the river banks? In the old days, grandma’s story would be true. But mankind has learned to regulate rivers with concrete banks, dikes, dams and barrages. Rivers’ courses become fixated. The floodplains (flat land areas around the rivers) are better protected from floods, and human populations along major river banks increase rapidly over time. As a result, economic value of the land behind dykes mounts up, and a flood event would cause ever more severe consequences. For centuries, dykes have been built higher and higher to protect the increasingly costly hinterland. But is that a sustainable way to live by the water?

The Dutch, at least, have realized that may not be the way. After two major floods in 1993 and 1995, they embarked on a huge project called “Room for the river”, in which they made modifications to flood protection structures at over 30 locations across the country. These modifications include setting back or lowering dykes, building dykes at different locations, and dredging new channels. The overall objective is to give more rooms for the water, and to let the floodplains do what they are meant to do – storing floods. Consequently, mean water levels are reduced by about 10 – 30 cm, and rather surprisingly, they actually managed to increase waterfront activities with a new island, new dwelling mounds, floating piers and viewing platforms.

This project is scheduled to complete this year. I learned about it in 2010 while doing my Master’s in Delft. It has been featured in the news on various occasions. Time will tell whether this is a successful endeavour, but I believe that in order to live in harmony with water, especially in a seemingly warming world, it is better that mankind adapt to nature than try to brutally regulate it.

References

  1. Loucks, D.P et al. (2005). Water Resources Systems Planning and Management. UNESCO Publication. (The book is publicly available on the UNESCO website).
  2. Room for the river project website
  3. Room for the river on Scientific American
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