Wetland forebays are a useful design tool to help improve water quality and to extend the life of lakes and detention or retention basins. Terra Technologies' expertise with wetland restoration and our understanding of hydraulics, hydrology, and geomorphology allows us to design effective and aesthetically pleasing forebays that also provide wildlife habitat.
One of the natural processes of streams is the transportation of suspended sediments. When a dam is built in order to transform an area that contains a stream into a lake or a detention facility, the result is that water that would have flowed quickly through that area now spends a considerable amount of time at the site. This change causes suspended sediments to settle and to accumulate over time, eventually filling in the area if action is not taken to remove the sediments. Maintenance dredging of lakes and other waterbodies is intensive and often prohibitively costly. The construction of a wetland area at the point where water flows into a lake, retention, or detention facility slows the flow of water which leads to the deposition of sediments in the forebay. The concentration of sediments in one portion of a waterbody allows for easier maintenance, thus lowering costs.
Wetland soils and plants actively absorb and transform nutrients such as nitrogen and phosphorus that are common constituents of urban and agricultural runoff. Increased levels of these nutrients often leads to an overabundance of algae and other undesirable aquatic plants. The eventual death and decomposition of these plants leads to a dramatic drop in the available oxygen in the water, which can cause fish die offs and impaired aquatic habitat and water quality. In addition to decreasing the amount of common nutrients, wetland forebays also accumulate heavy metals and toxic substances. The maintenance dredging of the forebay will therefore remove a portion of these substances from our streams and waterways.
Project Examples
Prairie Farms Low Impact Development Design, Olathe, Kansas
Rodrock Lake Detention Project, South Johnson County, Kansas
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