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A Natural Approach for Flood Damage Reduction and Environmental Enhancement.

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The frequency and severity of flooding in the Upper Mississippi River Basin is influenced by three major factors the amount and timing of precipitation the condition of the basins stream channels and floodplains, and the timing and rate of storm water conveyance off the watershed, which is a function of soil condition extent of impervious surface, vegetation density, and other factors. To the extent that changing precipitation patterns result from human-caused changes in the global climate, this factor can be addressed through international efforts to reduce emissions of greenhouse gases. Careful planning and design can provide some control over the condition of channels,, floodplains, and watersheds. The primary strategy employed by the United States and other developed nations for reducing flood damages has been to maximize the conveyance of storm water downstream and structurally alter channels and construct levees to protect adjacent communities from floods. Since the land behind 100-year levees was protected from flood stages with an annual probability of occurrence less than or equal to 1, development was frequently allowed to occur on lands that would otherwise be within the 100-year floodplain, with no additional requirements for flood insurance or flood protection. An emerging approach to flood damage reduction retains water on the upland landscape and focuses on allowing historical floodplains to again provide storage and conveyance benefits for reducing flood peaks. Floodplains under this approach are used for storing and conveying floodwaters, and also function as water filters and habitat for fish and wildlife. To the maximum extent possible. vulnerable structures are removed from the 100-year floodplain. This approach is referred to as the natural storage approach.

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  • Hydrology, Limnology and Potamology

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