The biggest culprits in flooding

The Gazette Editorial Board

It's another wet year in Iowa. Frequent flash flooding and persistently high levels in streams stir fears of another flood of 2008 or something near that scale. And once again, farm drainage tile's effects on flooding is being debated.

Problem is, there is no definitive scientific study documenting how much widespread use of drainage tile impacts flood levels, several state experts recently told The Gazette. Such documentation could be useful as this state's leaders grapple with how to better manage watersheds and reduce the risk of severe flooding.

However, it's clear enough that making drainage tile the chief villain is off target and impractical. Instead, the biggest culprits are:

l 160 years of development, especially the past six decades, that turned natural wetlands and prairie, which have deep roots and hold more water,

into cultivated fields dominated by row-crops of corn and soybeans.

l More rain - statewide average annual precipitation has increased 10 percent in the Corn Belt, including Iowa, since 1950. Heavy rainfall incidents and periods are more frequent, and weather experts say it's likely to continue.

So, we should try changing Mother Nature's tendencies? Good luck with that.

But modifying land use can be part of the solution. Consider: In 1950, 35 percent of Iowa land being farmed was planted with corn and soybeans. Today, it's nearly 80 percent. Water-absorbing hay, oats and grass pastures were largely replaced with row crops.

So, blame farmers again?

Well, not so fast. U.S. farm policy over the last half-century essentially encouraged farmers to plant row crops via taxpayer-supported programs that lessened financial risk.

Yet returning to the days when the state was 80 percent prairie isn't realistic. Agriculture is critical to this state's economy, supporting a variety of industries and thousands of jobs beyond the cornfield.

That doesn't mean we should accept status quo. The billions in flood damage in Cedar Rapids alone in 2008 demands change in how watersheds are managed. Levees and flood walls won't fix the overarching problem. Building huge new reservoirs appears cost prohibitive and too disruptive.

But if this nation remains tied to taxpayer-supported agriculture, then consider changing government policy. Provide incentives to encourage more perennial crops.

Proven ways to reduce runoff from farm fields also deserve more attention: grass waterways, terraces, buffer strips near streams, wetland restoration.

Many Iowa farmers in recent years have incorporated some better land-use practices. But so much more remains to be done. Figuring out how to make it happen without wrecking our farm economy is a challenge Iowa must tackle.