Natural Functions of Stormwater Management

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Ecological function

Alabama’s riverine floodplains and watersheds support and promote biological productivity.  These water bodies often contain large and diverse populations of plant and animal life that contribute to the diversity and integrity of adjacent and downstream ecosystems.  Storm water that contains urban pollutants will enter watershed and streams and are carried downstream into larger water sources. Many plant and animal species native to local floodplains and watersheds are adapted to thrive in very specific environmental conditions created by soil and water systems. Many species of plants depend on the delicate dynamics between these systems to flourish, which subsequently affects breeding and spawning of many types of wildlife that feed on that vegetation.

Sustaining vegetation in a floodplain or watershed provides habitat and food for wildlife, controls erosion and sedimentation, and improves water quality by filtering pollutants.

The shading effects of riparian vegetation are beneficial for avoiding temperature extremes that stress an ecosystem. Removal of streamside vegetation can lower oxygen levels in the water, making it more difficult for aquatic species to migrate, reproduce or complete their life cycles.


Wetland Information 

Wetlands act as a natural buffer against flooding by storing and slowly releasing floodwaters. They also improve and protect water quality by filtering pollutants and sediments from storm water runoff. Wetlands are a critical habitat and food source for native wildlife that depends on specific conditions for survival; they are a highly productive ecosystem essential for maintaining biodiversity within a watershed. Fish, shellfish, waterfowl and a wide variety of other aquatic and semi-aquatic species reside in a wetland environment, 60-70% of these species being endangered or threatened by habitat removal.


Filtering pollutants

Urbanization presents a threat to water quality of waterways through different sources of storm water pollution. Agricultural run-off, fertilizers, failed septic systems as well as industrial plant discharges are all sources of water pollution. Water entering a floodplain or watershed carries these sediments and pollutants from storm water runoff. Excess sedimentation and turbidity degrades water quality, raises water temperature, changes conveyance rates and increases floodwater heights. These affects can be mediated via vegetated floodplains and watersheds.  These ecological systems naturally control erosion and sedimentation by stabilizing riverbanks and filtering run-off. Water is cleansed through natural biological processes that occur this filtration process, reducing levels of pathogens and toxic substances.