Flood Plains are for Floods
Every month or so TV screens are filled with images of desperate people somewhere battling a flood.
Floods have been reshaping the Earth for billions of years. And some past floods were far larger than modern floods, evidenced by the width of many flood plains - seldom are they completely flooded today.
The majority of cities and many country homes were built on flood plains, and for good reasons - closer to water, with fertile soil, better groundwater, flat country that is easier to build on, near good fishing holes and shady trees, and periodically re-fertilised with silty topsoil. Sensibly, many early settlers built their homes on stilts.
We hear alarmist stories about the soaring costs of floods. That is not usually because the floods are bigger – it is just that more people are building more costly homes and infrastructure on flood plains near the mouth of scenic rivers.
Those who choose to build/live on flood plains must accept the costs that go with it – occasional flooding and expensive flood insurance. But a nice home on flood-prone land will usually cost less than a similar home on the hill with views.
Long term flood problems are increased when government steps in and “helps” those who buy/build on flood-prone land with repair subsidies, public works or insurance caps. This allows risk-takers to escape the real cost of their decisions. Then more people build on flood plains.
Flood diversions and levees may not help – too often they just shift flood water from one piece of land to another. Commonly, they also increase water speed, thus increasing the erosive power of the flood.
But governments must ensure that essential infrastructure is relatively flood-proof – roads, railways, airports and electricity should remain operational during most floods. And strategically placed dams will moderate the extremes of both floods and droughts.
Global warming can’t be blamed for more floods because, for 17 years, there has been no global warming.
Flood plains are for floods. Those who choose to live there must expect to get flooded.