Waterways, Wetlands and Floodplains

Aerial view of Gunbower Forest in flood. Spring 2003

Environmental water flooding of River Red Gums

Waterways, wetlands and floodplains are those parts of the region's natural landscapes where water collects and through which it flows. The asset includes the Campaspe, Loddon, Avoca, Avon and Richardson rivers, their tributaries and the region's lakes and wetlands. This asset class focuses on the habitat provided for riparian, wetland and aquatic ecosystems and their function in conveying and retaining water.

Waterways, Wetlands and Ecosystem Services

Waterways, wetlands and floodplains are key life support systems in their own right and help to protect water resources. In doing so they provide a range of ecosystem services. These services include:

• maintenance or improvement of water quality - riparian vegetation helps to capture sediment and nutrients in surface run-off and reduces the amount entering streams. It also helps to stabilise stream banks and reduce the contribution of bank erosion to sediment load
  
• maintenance of channel form and flow capacity - the roots of riparian vegetation help to stabilise stream banks and maintain channel morphology.  This helps to slow channel migration and maintain the capacity of the stream to convey water
  
• provision of habitat - wetland and waterways are focal points for mobile fauna in a generally dry landscape. They provide refuge in summer and during times of drought. Riparian vegetation also modifies aquatic habitats by providing shade and woody debris
  
• provision of energy and nutrients for aquatic ecosystems - leaf litter from riparian vegetation is a key source of carbon and nutrients for aquatic ecosystems. They collect sediment, build soils, recycle nutrients, assimilate wastes and filter water
  
• soil formation - silt carried by streams during overbank flood events helps to build up soils on floodplain area. Many of the region's most productive agricultural soils are located in such areas.

Nature Conservation

Great Egret - Photo: David Kleinert

Kow Swamp - Cultural Diggings

Many of the region's wetlands, particularly those in mid and lower catchment areas, have international conservation significance. The Kerang Wetlands and Gunbower Forest have been listed under the International Convention on Wetlands (the 'Ramsar Convention'). Other wetlands are significant at national or state level. Many wetlands attract birds that are protected by international migratory bird treaties, such as JAMBA, CAMBA (and the Bonn Convention). While the treaties are concerned with protection of the bird species, they do require government to protect habitat. Waterways and wetlands are often the only areas of retained native vegetation in mid and lower catchment areas of the region. However, even these communities are mostly substantially depleted and have high conservation status. They also provide habitat for native fish and water birds.

Cultural Heritage

The availability of water and food meant that waterways and wetlands have been focal points for human populations for millennia. These places retain great cultural significance for Indigenous communities. A number of Aboriginal and archaeological sites have been identified across the region and registered on the Aboriginal Affairs Victoria database. These sites may include isolated artifacts, rock shelter/caves, burial sites, shell middens and scarred trees. For example, Kow Swamp is a particularly important regional archaeological site.

Recreation and Amenity

The region's natural lakes and wetlands provide important recreational opportunities to tourists and members of the local community. They are used for fishing, boating, swimming, bird watching, camping, as meeting places and for hunting. In drawing visitors to an area, they can contribute to economic activity. Recreational fishing alone has been estimated to inject $78 million into the economy of North-West Victoria.

Flooding

The region's floodplains are the natural paths by which floods are conveyed to the Murray River or lower catchment lakes and wetlands. Development on floodplains has resulted in average annual damage bills from flooding, running to over $23 million. Flooding is an important natural process in lowland river systems. It helps to maintain channel form and is often an essential ingredient for regeneration events. Periodic flooding also flushes salts from the root zone of riparian and floodplain vegetation and is essential in preventing the soils from becoming salinised.

Salt Disposal

Several of the region's wetlands are used for salt disposal. Salt interception schemes involving Lakes Tutchewop, Kelly, Little Kelly, and William, near Kerang, contribute to a 13 EC unit reduction in Murray River salinity (measured at Morgan in South Australia). While damaging to the natural environment of these wetlands, this use provides substantial benefits for downstream communities and helps to protect irrigated agricultural land, the Murray River and other waterways and wetlands from the effects of salinity. Wetlands used for salt disposal may also present opportunities to develop commercial salt or mineral harvesting or saline aquaculture enterprises. Some streams in the lower catchment irrigation areas form part of the regional drainage network and help to protect adjacent land from water logging and salinity. There has been a dramatic reduction in natural wetland area since European settlement. Thirty seven per cent of Victoria's wetland area has been lost, primarily as a result of drainage.

Water Supply Infrastructure

Many of the region's lakes and waterways have been incorporated into the supply network for domestic, stock and irrigation water supplies. This has resulted in substantial changes to the character and values of a range of wetlands due to the change in hydrology. Some wetlands experience more frequent wetting cycles and even permanent inundation, whilst other wetlands have been cut off from supply and are subject to much drier regimes. The goal for North Central Catchment Management Authority Waterways, Wetlands and Floodplains as outlined in the Regional Catchment Strategy is:

Waterways and wetlands will be managed to enhance their environmental function and, where appropriate, provide opportunities for economic, recreational and amenity use.