Skip to main content

Competency Area 6: Watershed hydrology AEM

PO 67. Understand key processes that occur in wetlands and riparian buffer zones and their role in a watershed.

Wetlands are areas of wet soil (hydric soil) that is inundated or saturated under normal circumstances, and would support a prevalence of hydrophytic vegetation (plants adapted to survive in low soil oxygen environments). Key processes that occur in wetlands, in addition to providing diverse biota and wildlife habitat, are to slow the transport of water and provide surface water storage (unless already filled), resulting in the retention and removal of suspended and many dissolved pollutants. For example, denitrification and reduction of other chemical compounds (pesticides) are a key function. Wetlands are quite effective at removing suspended and particulate materials, such as phosphorus bound to soil particles, but are less effective at retaining dissolved phosphorus.

Riparian buffer zones (an area of land immediately adjacent to water bodies) share many of the same characteristics and functional processes of wetlands, but depending on their position in the landscape are generally less saturated.

Thus, riparian buffers may also serve to infiltrate incoming surface runoff, facilitating the removal of suspended and some dissolved pollutants that readily absorb to soil. When streams flood, water flowing out into the riparian buffer may also be cleansed as sediments, nutrients, and other pollutants are attenuated (reduced and retained) in the buffer zone.