|Better approaches to river management and flood damage prevention|
This article was written for the WRC NEWSBRIEFS which is a monthly publication of the Windham Regional Commission. The WRC is a partner with the Windham District in all of our Fluvial Studies and Projects.
Fluvial Geomorphology is quite a mouthful, and we’ll be hearing and talking about it a lot. We’ve discussed this relatively new science before, and it’s worth reviewing because a lot is happening at the state level and across the country. Fluvial means related to a river or stream, from the Latin word for river “flumen.” And from the Greek words for earth (gi, or ge) and form (morfe) we get geomorphology meaning the study of land forms.The Vermont Agency of Natural Resources, Department of Environmental Conservation (DEC) has made significant advances in this area and is probably one of the national leaders in its implementation to help cities and towns understand their river and stream systems and to avoid or minimize damage when natural flooding events occur. The DEC website contains a lot of information that can help local planners, though much of it is fairly technical, and they have produced a DVD that explains the science and the program clearly. The DVD has six segments ranging from 9 to 15 minutes in length, and we have a couple of copies at the Windham Regional Commission that we can make available for use at a planning or conservation commission meeting.
Rivers and streams have a lot of energy, and they are constantly seeking equilibrium. We often control them with dams, levees, rip-rapped banks, straightened channels, etc., but time and again we see rivers reclaim floodplains, sometimes with tragic consequences. That’s where fluvial geomorphology comes in, in part because rivers and streams are not only moving water, but also of sediment. As it flows over its bed and against its banks, a stream erodes material that it transports downstream, either as bedload, suspended load or dissolved load. When we prevent a river from picking up or depositing material naturally, we really are only forcing it to transfer its energy to another location, usually downstream, and often with serious impacts.
Flooding is a major part of Vermont’s natural history, and serious flood damage is an unfortunate part of the state’s human history. It’s generally accepted that weather patterns are changing with storm events tending to be more severe, which means that flooding remains inevitable and flood damage will increase. We all need to improve the way we manage stream corridors, and the Vermont River Management Program can be a big help.
The new program attempts to move stream management from an engineering and construction focus to a more interdisciplinary approach that considers a wide range of strategies and land use measures. It changes the primary objective of stream management from stabilizing and controlling a stream, to recognizing that natural variability is inevitable and working with it. It accepts that uncertainty is part of the natural function, and so works toward land use and development that will avoid or minimize damage. It urges us to revise our planning and land use regulations to, quite literally, “go with the flow.”
As the DEC website notes: “Nearly every stream and river in the state of Vermont is undergoing change. Sometimes these changes are natural or imperceptible. Other times, and more often, streams and rivers are adjusting to channel, flood plain, or watershed changes imposed in years past by human activity. Understanding the natural tendencies of a stream, its current condition, and what changes may be anticipated in the future is invaluable to making sound protection, management, and restoration decisions.”
For more information about the state program, see: www.anr.state.vt.us/dec/waterq/rivers/htm/rv_geoassess.htm .
|Last Updated ( Thursday, 10 April 2008 )|
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