Floodplains in their natural state regularly flood. As a result, many areas are left as grass and sheep and cattle are left to graze. Makes sense. If the river is about to flood there is usually enough warning for the farmer to herd the animals to higher ground.
However, floodplains are very flat, and the flooding river regularly deposits extra nutrients, making the soil particularly good for growing crops. The flat land makes it easy to use a tractor and other equipment. So, you will find crops growing close to rivers, even with the risk that a flood could ruin the crop any time.
Flat floodplains are also used for housing. It is easy to build where it is flat and on larger rivers there may be employment at a port or riverside industry, so there is a demand for housing.
Do you see how, as we move from grazing to crop growing to housing, the risk is increasing? The dairy farmer might have to move his cows for a while. The arable farmer could lose his whole crop. An entire neighbourhood could find their houses flooded.
The greater the risk the more money is likely to be spent on trying to ensure that the river stays in its channel.
Last week we saw how a river naturally creates levees and a fairly simple option is to make these higher. But where there is more at stake, major engineering projects can be put in place. We’ll look at some examples next week.