Floodplains by Design (video) Floodplains By Design
Important Ideas During severe floods, floodwaters rise beyond banks and can reach the upper part of the floodplain. Communities often grow within floodplains. Structures such as dams, reservoirs and levees protect communities from flooding. During severe floods, water can overtop these structures. Restoring floodplain to a natural state, such as wetlands, may help to alleviate flooding. Flexibility is important to flood management to operate according to severity of flood.
Problem A number of factors can contribute to flooding, including: Heavy Rain Snowmelt Impervious Surfaces Upstream Conditions Certain areas are more susceptible: Highly Developed Areas Cities Suburbs Floodplains
Tools Watershed Planning Flood Control Structures Dams Levees Reservoirs Green Infrastructure Wetlands Green Roofs Rain Gardens Bioswales Rainwater Harvesting Systems And Much More!
Example Bower Elementary School Incurred approximately $1.7 million in damages from a flood event in 2008. Was forced to close for 1 week. Unable to use half of the building for 6 months. Why did this happen? Built in floodplain. Existing berm (levee) along West Branch DuPage River settled over the years and could not contain floodwater.
Possible Solutions Build a dam upstream to prevent water from coming downstream. Tear down school and restore floodplain. Enhance existing berm. Install green infrastructure to soak up water. Build a reservoir next to school. Elevate school to bring usable area out of floodplain.
What Solution Did We Use? Enhanced Existing Berm Most cost effective solution. Built extra storage for floodwater downstream. Did not adversely affect other properties. Built pump to drain rainwater trapped on opposite side of berm. Did it work? In April 2013, Bower Elementary did not flood despite river elevations 9 ft. above normal.