Land development partially to blame for flooding
Christopher Patton - The Daily Iowan
Issue date: 7/18/08 Section: Metro
Iowa hasn't always been quite so flood-prone.
The state's native prairies originally absorbed most of the rainfall, but their development has led to increased runoff and flooding.
Wayne Peterson, an urban conservationist working for the Iowa Department of Agriculture and Land Stewardship, said the state's landscape processed rainwater quite differently before most of the natural habitats were developed into agricultural fields and urban areas. Peterson worked in the field of agricultural land conservation for more than 20 years before becoming involved with urban issues.
"Two hundred years ago, Iowa was full of prairies, savannas, and wetlands," he said. "The vast majority of the time when it rained, the rain infiltrated into the soil, moved through the soil matrix, and became part of the groundwater discharge into the river."
This process maintained a stable rate of water drainage, Peterson said, and Iowa's wetlands, streams, and rivers would not have seen water levels move quickly up or down nearly so frequently as they do now had the prairie remained intact.
Having written a book about the effect of development on Iowa's natural environment, Connie Mutel, historian and archivist of IIHR - Hydroscience and Engineering at the UI, agreed with Peterson that changes to the state's ecosystems radically altered how water drains from the soil.
"Iowa was 80 percent prairie, the heart of the tall-grass prairie," she said. "The prairie soils were very thick and extremely high in organic matter and mineral particles."
Those soil components held it together in small clumps that allowed for numerous air pockets between them, Mutel said, and the air pockets enabled the soil to act as a sponge and soak up significant amounts of water. However, killing the prairie grass and repeatedly plowing the soil collapsed those pockets, meaning the soil no longer absorbs water as it once did.
And with nowhere else to go, the water simply runs downhill and immediately enters the river system, she said. This causes water levels to rise more quickly and higher than they would have in a natural state, she said.
The state's native prairies originally absorbed most of the rainfall, but their development has led to increased runoff and flooding.
Wayne Peterson, an urban conservationist working for the Iowa Department of Agriculture and Land Stewardship, said the state's landscape processed rainwater quite differently before most of the natural habitats were developed into agricultural fields and urban areas. Peterson worked in the field of agricultural land conservation for more than 20 years before becoming involved with urban issues.
"Two hundred years ago, Iowa was full of prairies, savannas, and wetlands," he said. "The vast majority of the time when it rained, the rain infiltrated into the soil, moved through the soil matrix, and became part of the groundwater discharge into the river."
This process maintained a stable rate of water drainage, Peterson said, and Iowa's wetlands, streams, and rivers would not have seen water levels move quickly up or down nearly so frequently as they do now had the prairie remained intact.
Having written a book about the effect of development on Iowa's natural environment, Connie Mutel, historian and archivist of IIHR - Hydroscience and Engineering at the UI, agreed with Peterson that changes to the state's ecosystems radically altered how water drains from the soil.
"Iowa was 80 percent prairie, the heart of the tall-grass prairie," she said. "The prairie soils were very thick and extremely high in organic matter and mineral particles."
Those soil components held it together in small clumps that allowed for numerous air pockets between them, Mutel said, and the air pockets enabled the soil to act as a sponge and soak up significant amounts of water. However, killing the prairie grass and repeatedly plowing the soil collapsed those pockets, meaning the soil no longer absorbs water as it once did.
And with nowhere else to go, the water simply runs downhill and immediately enters the river system, she said. This causes water levels to rise more quickly and higher than they would have in a natural state, she said.
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Joe B
posted 7/18/08 @ 9:50 AM CST
I'm sure all the sprawl in North Liberty and surrounding communities will help. First we destroy the prairies for farmland. Now we destroy the farmland. (Continued…)
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