Housing estates and commercial development along the water’s edge commonly involve the removal of riparian vegetation to provide better views and access to the water.
Poor control of sediment on building sites and insufficient vegetation to stabilise riverbanks result in sediment washing into our waterways. This creates muddy water that has reduced light penetration and impacts aquatic plants and animals.
High nutrient loads
Unnatural pollutants in stormwater discharge from urban areas can impact the health of a waterway. High nutrient loads speed up growth of aquatic weeds and algae which disrupt the ecosystem. Furthermore, bacteria in water that helps break down nutrients use oxygen during the process. High nutrient loads therefore deplete dissolved oxygen levels in the water column and can lead to fish kills.
Boat wash erodes stream banks which increases sediment load and depletes the riparian landscape.
Dredging erodes the riverbanks, widens the stream, increases sediment loads and impacts on the aquatic environment.
Sparse and fragmented riparian vegetation results in greater light penetration and the opportunity for weed plant species to thrive and out-compete native species. Riparian areas that are dominated by weeds have decreased plant and animal diversity. Weed species often have shallower root systems which compromise their role in bank stabilisation.
Please note existing weeds may be providing some bank stability and habitat. This is why it's important that appropriate weed control methods are used.
Degraded riparian vegetation results in poor habitat for native fauna. Pest fauna, commonly with less specific food and habitat requirements, out-compete native species and dominate the riparian environment, resulting in reduced biodiversity.
When stock access is not restricted, substantial damage can be caused by overgrazing, weed dispersal, formation of tracks, physical degradation of the stream bank and water contamination through the high nutrient content of dung and urine. Stock also can dislodge river rocks, submerged or protruding logs and branches that provide habitat and reduce water velocity.
Vegetation creates a buffer from fluctuations in air temperature and evaporation of water. Reduced light intensity minimises excessive growth of nuisance plants and algae. Shading also alters the in-stream ecology providing habitat for both predators and prey.
Established riparian vegetation including a range of mature trees and understorey plants provide a strong network of roots. These roots stabilise soils and provide strength to the stream bank. This prevents bank erosion during high stream flows and reduces sediment from entering the waterway.
The diversity of vegetation that exists within riparian environments provides habitat for animals with specific requirements. For example platypi feed on aquatic insects that live among the dead leaves, woody stems and branches that accumulate in riparian areas. Riparian environments also provide wildlife corridors that enable the movement of native wildlife and plants between habitats.
Natural filtration of runoff waters
Riparian vegetation assists in removing pollutants from urban water runoff through the understorey, leaf litter and soil.
Flood and sediment control
Riparian vegetation helps to reduce water flow and sediment transport during high rainfall by creating friction along the stream bank. This natural process controls large volumes of water without flooding.
In-stream nutrient source
Native riparian vegetation is an essential food source for many aquatic plants and animals that rely on flowers, insects, leaf litter and other organic debris that fall into the water. This helps to sustain complex food webs by providing the basic nutrients for plant growth. They are a major part of the diets of many native aquatic fauna animals such as turtles.
High water quality
The health of waterways usually is reflected in the quality of the water. Established riparian areas help to clean the water through physical and chemical means. Aquatic bacteria for example contribute to maintaining water quality through the breakdown of nutrients.
Large wood found in our waterways includes fallen trees, sticks, bark and leaves. Large wood is an important natural component of instream aquatic ecosystems. The benefits of large wood in our waterways includes:
- Stabilises river bed and banks by diverting/decreasing flows and resisting erosion.
- Provides habitat for a range of aquatic plants and animals.
- Improves water quality by increasing available oxygen for fish and reducing odours.
- Decaying wood is an important source of food for some aquatic invertebrates and fish.
- Provides perches, resting, foraging and lookout sites for birds, reptiles and mammals.
- Many aquatic invertebrates have a terrestrial adult stage. Dragon flies for example rely of large wood that juts out of the water so they can complete their life cycle.
Re-introducing large wood in streams
Past clearing of vegetation has resulted in the removal of valuable sources of large wood in many local waterways. Throughout the world, river managers are reintroducing large wood to stabilise our waterways. A local example is the Damian Leeding Foreshore Stabilisation Project (Coomera estuary).
If you are concerned with the amount of large wood collected in your stream and would like it checked, please contact the City’s Catchment Management Unit on 1300 GOLDCOAST (1300 465 326) or 07 5582 8211 or alternatively you can email firstname.lastname@example.org
You can take steps to improve the health of riparian environments:
- If you live on a waterway, plant local, native species along the stream bank and control weeds.
- Reduce boat speed on the water to minimise boat wash.
- Restrict stock access by erecting fences at an appropriate distance from the waterway.
- Get involved with local community catchment and bushcare groups. They're located throughout the Gold Coast and help preserve and improve our waterways.
- Stormwater pollution affects the health of our waterways and has a direct impact on the health of riparian ecosystems.
- Educate friends and family on the importance of riparian environments and how they can improve our waterways.
The City is continually restoring and preserving riparian vegetation. The City is also developing catchment-based management plans for all major catchments. They identify the issues that are impacting our waterways including degraded riparian environments. Part of these management plans is the identification of priority areas for restoration. This will ensure the most effective use of labour and resources.
Community education programs increase awareness to protect our waterways and their supporting environments. The long-term viability requires an integrated approach with concerted efforts by government, industry groups and the general public. Please help to protect our waterways. They are our future.