Rivers flood

To begin, a quote:

“Clean out the rivers, repair the river banks and keep the water where it belongs…IN THE RIVER.”

There is an age old saying among fluvial geomorphologists that I’ve just made up, and it is ‘never buy a house on the floodplain’. I live on a hill. Simon Dixon lives on a hill. My PhD supervisor David Sear lives on a hill. This may or may not be a coincidence.

Restricting a river to its channel is not sustainable in the long term

The name prescribed to the floodplain is literal; it is the land adjacent to a river that is inundated with water when the flow in the river is elevated above its banks. This floodplain area will generally increase in size as you move further down the river course, and may be characterised by relic channels marking the former location of the river. In most rivers the floodplain acts as an important transitional zone for the exchange of nutrients and sediment between the aquatic and terrestrial environments. Indeed the entire water meadow system that characterises much of southern-England’s grazing pasture is based upon this exchange.

So floods are natural and normal. The average river will probably experience out-of-bank flows between one-three times each year. These relatively predictable floods are punctuated by extreme events, the magnitude of which is typically defined by their frequency (e.g. a one in 25 year event). It’s often the extreme events that receive the most attention and affect the most people, with the 1953 floods being a prime example. Extreme events also tend to  have the most impressive geomorphic consequences; although all floods play a role in the connection between aquatic, riparian and terrestrial environments.

Bank slumping due to scouring at the toe of the bank during overbank flows

Now all of this would be fine if we hadn’t spent centuries trying to stop our rivers flooding. An expanding population and a restriction on space have led to extensive developments on many floodplains, with flood defences creating complacency amongst homeowners. Where there is arable agriculture, a history of dredging and maintenance activites have made some farmers believe that rivers should not flood. The quote at the start of this post has been taken from the comments section at the bottom on this article in the Farmers Guardian. The rest of the comments also make for interesting reading.

Simon has recently discussed the public perception of rivers, and there is clearly scope and room to educate stakeholders. How do we do this? Engagement. Take children to their local river and teach them about the way it works. Show them its value and share with them your understanding of its importance. With the increasing influence of technology and whizzy electronic gizmo’s there’s every chance that the our kids will be more disconnected from the natural world than any previous generation. It’s very difficult to take care of something you don’t understand.

And if you’re not young and you’re not sure about how rivers work then have a look around our blog. River management is not easy but a good starting point is understanding how rivers naturally manage themselves, and the irrevocable truth is that rivers flood.


About Trevor Bond

A Geomorphology Technical Officer at the Environment Agency. All opinions expressed herein are my own and do not necessary reflect the views of my employer.
This entry was posted in Flooding, Geomorphology, Hydrology and tagged , , , , , , , , , , , , , . Bookmark the permalink.

3 Responses to Rivers flood

  1. Pingback: Politik | The River Management Blog

  2. Pingback: A Few Good Reads (2/11/13): The Recovery in Australia » Hydraulically Inclined

  3. Mark Lawson says:

    Interesting post Trevor. I currently live in a floodplain area, in the Oderbruch, eastern Germany. We come under various threats of flooding from the great river Oder every year, usually spring time when the snow melts in the mountains upstream. Keeping the water where it belongs is number one priority here.

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