Riparian - relating to or situated on the banks of a river
Aquatic and riparian vegetation is important for the health of waterways, contributing to the balance of oxygen, nutrients and sediment, and providing habitat and food for fauna.
Aquatic plants and algae grow within the waterway channel. Some are completely free floating (e.g. filamentous green algae) but most have roots or root-like structures in the sediment and can have floating leaves (e.g. water lilies), structures emerging from the water (known as emergent plants e.g. water ribbons) or be completely under water. These are known as submerged plants and include curly pondweed and seagrasses.
Riparian vegetation grows along banks of a waterway extending to the edge of the floodplain (also known as fringing vegetation). This includes the emergent aquatic plants growing at the edge of the waterway channel and the ground cover plants, shrubs and trees within the riparian zone.
Riparian vegetation often shows zonation in the plant species present as the environment changes from permanently or seasonally aquatic habitats in the waterway channel and floodplain wetlands, to frequently flooded habitats along the banks and close to the channel, to drier habitats at the edge of the floodplain.
Aquatic plants, algae and riparian vegetation play an important role in keeping waterways healthy by:
absorbing nutrients from water flowing into a waterway - over the land surface and through groundwater - and from the waterway itself
slowing the water flowing over the land surface into a waterway – this allows sediment and pollution in the overland flow to deposit in the fringing zone, reducing sedimentation and pollution of the waterway
stabilising the banks and bed of a waterway. Plant roots bind the sediments to reduce erosion
oxygenating a waterway – oxygen is a by-product of photosynthesis, the process by which plants and algae make sugars from carbon dioxide and water using sunlight
providing elements for the food web such as carbon, nitrogen and phosphorus
providing habitat for aquatic fauna and terrestrial fauna, such as turtles and frogs, including migration corridors
shading a waterway – this helps to control water temperature and reduce the growth of phytoplankton which helps prevent algal blooms
providing a physical barrier to prevent access by stock - which can lead to erosion and nutrient inputs - and to prevent the spread of weeds via the waterway.