Questions

An obvious question to be asked is, why has sedimentation been allowed to become such a problem? The answers are not easy because the problem is very complex. From an environmental perspective, there are many factors that contribute to soil erosion and sedimentation. Annual rainfall affects soil erosion - flooding dramatically increases sheet and rill and bank erosion. Soil type is also a factor. Clay soils produce more runoff than do loess soils, although loess soils will collapse when saturated. This can lead to severe bank erosion.

There are economic factors that affect soil erosion and sedimentation. Land is converted from its native vegetation for other uses, such as agriculture and a wide range of urban development - houses, stores, and highways. As land is developed, pervious surfaces are replaced with impervious surfaces - rooftops, roads, driveways, and parking lots. This replacement increases the amount of water that runs off during storm events, taking with it soil and pollutants. While best management practices exist to increase the infiltration of water and reduce runoff, they are difficult to impose on landowners. Why is this?

The largest percentage of land in the state of Illinois is privately owned. This makes it more difficult impose regulations. Many people and organizations strongly oppose being told what to do with their property, even if their actions affect other landowners or damage the environment.

People join organizations that lobby local and state officials and Congress to ensure their land will not be affected by land use regulations. Politicians too often listen to these organizations in an effort to ensure having the support to be re-elected.

Time scales also affect soil erosion and sedimentation. Actions taken today may not be visible on the land or water for many years, both good and bad. For example, experts tell us that it can take 35-50 years, or more, for soil erosion control measures to have a measurable effect on sedimentation. There is so much sediment in the system that it will require decades for it to be cleansed from the system, even if sedimentation is stopped today.

These are a few reasons that allow sedimentation to be a problem - environmental factors such as rainfall and soil type, private property issues, politics, and the complexity of environmental systems. Can you think of other reasons? Can you think of anything we can do to help reduce soil erosion and sedimentation?