Floods and flood damage

This year’s devastating floods in the Midwest, followed by predictions that 25 states will see flooding through May bring to mind an oft-quoted statement by Gilbert White, a prominent geographer in Chicago in the 1930s who wrote that “floods are acts of God, but flood losses are acts of man.”

Based on recent news reports, the Creator has been busy: heavy rains last summer, frozen ground last winter and big snowmelt this spring have filled rivers to bursting.

Floodwaters image.jpg

At the same time, humans have lent a hand, according to a study of climate change by Yale.

As for damage from floods, White was right to blame humans. We’ve built homes too close to rivers, exposing them to danger. We’ve paved over floodplains and drained wetlands for various purposes, one effect of which has been to prevent rain from soaking into the ground and instead wash into streams and rivers – ultimately to channel stormwaters downstream to do damage there.

In the course of researching “Water Connections,” I came upon all sorts of ways that humans have invited floods. One of the more fascinating discoveries was an advertisement in American Farmer magazine in 1935 by E.I. duPont de Nemours, the chemical company, for a 48-page book  that was titled “Ditching with Dynamite.” Here was the pitch:

“Crooked streams are a menace to life and crops in the areas bordering their banks. The twisting and turning of the channel retards the flow and reduces the capacity of the stream to handle large volumes of water. Floods result. Crops are ruined. Lives are lost. Banks are undermined, causing cave-ins that steal valuable acreage… Dynamite may be used most effectively in taking out the kinks in a crooked stream.”

Most hydrologists and flood experts know that straightening a stream in one place merely speeds up the flow of water downstream to wash out roads, soak homes, and lift bridges off their footings. Meandering streams, on the other hand, check the rush of stormwaters. And floodplains, if they aren’t paved over, soak up floodwaters and then gradually release them later on, effectively checking the blunt force and effects of floods.

This fact – that, left to themselves, rivers and surrounding floodplains can handle heavy rains and snowmelt quite well – has been known for some time by some people, notably Paul Sears, an ecologist in the 1950s who chaired one of the country’s first graduate programs in conservation, at Yale.

In 1955 he presented an ambitiously titled paper at an international symposium in Princeton, N.J. -- “Man’s Role in Changing the Face of the Earth” – that contained the following passage:

“Far greater funds are expended upon efforts to control flood after water has reached the river channels than are devoted to securing proper land use on the tributary uplands to retain the water where it falls. This is an interesting aspect of a technological culture where emphasis is on engineering rather than on biological controls.”

The floods this year may cause some people to go looking into what Professor Sears had to say, and then adjust their laws and flood-control practices accordingly.