Riparian Buffer - Buffer Design

Buffer Design

A riparian buffer is usually split into three different zones, each having its own specific purpose for filtering runoff and interacting with the adjacent aquatic system. Buffer design is a key element in the effectiveness of the buffer. It is generally recommended that native species be chosen to plant in these three zones, with the general width of the buffer being 50 feet (15 m) on each side of the stream.

Zone 1. This zone should function mainly to shade the water source and act as a bank stabilizer. The zone should include large native tree species that grow fast and can quickly act to perform these tasks. Although this is usually the smallest of the three zones and absorbs the fewest contaminants, most of the contaminants have been eliminated by Zone 2 and Zone 3.

Zone 2. Usually made up of native shrubs, this zone provides wonderful habitat for wildlife, including nesting areas for bird species. This zone also acts to slow and absorb contaminants that Zone 3 has missed. The zone is an important transition between grassland and forest.

Zone 3. This zone is important as the first line of defense against contaminants. It consists mostly of native grasses and serves primarily to slow water runoff and begin to absorb contaminants before they reach the other zones. Although these grass strips should be one of the widest zones, they are also the easiest to install.

Streambed Zone. The streambed zone of the riparian area is linked closely to Zone 1. Zone 1 provides fallen limbs, trees, and tree roots that in turn slow water flow, reducing erosional processes associated with increased water flow and flooding. This woody debris also increases habitat and cover for various aquatic species