The Barwon-Darling The Riparian Zone

WESTERN

The areas along a river including its banks, floodplains, billabongs, flood channels and wetlands are known as the riparian zone. The condition of riparian lands is vitally linked to water quality and the health of aquatic ecosystems.

Freecall 1800 032 101 WESTERN www.western.cma.nsw.gov.au Email: [email protected] Landscape meandering river before changing to a mud- The upper catchments of the Darling and Barwon dominated system. in Northern NSW and Southern Queensland flow onto a series of overlapping, low gradient alluvial fans, converging upstream of Bourke into a narrow floodplain. The floodplain is extensive. Due to the relatively level nature of the land, a flood can slowly spread for tens of kilometres across the landscape before it is confined by higher terrain or ‘red country’. Towns such as Tilpa and Louth owe their location to the higher red country occurring very close to the River, which during wet times were not as prone to flooding and bogging, and meant that the River could still be accessed.

Floodplains Floodplains operate in large flood events where the river channel exceeds its banks and flows into the adjacent countryside. They are important areas for The Darling River during the drought. Photograph probably taken near Winbar, NSW c. 1908 - 9. Photo: Charles Bean, private collection of CEW biodiversity, vegetation and pastoral production. Bean held at the Australian War Memorial. Negative number PO 2751.160. Tilpa comes from ‘Thulpa’ in the local Aboriginal Baarkindji language which means ‘floodwaters’. Vegetation and riverbanks Riparian vegetation plays a crucial role in the health of The Darling River is the primary source of alluvial the river and the biodiversity that relies on it. deposits along the floodplain. At Tilpa sheets of alluvium are up to 60 metres thick. The floodplain Insects that eat riparian vegetation are an important landforms and layering of sediments provide a good food source for fish. Trees and fallen branches in the record of changing environments over thousands river provide habitats for fish, shade and refuges for of years. For instance, the Darling was once a sandy native animals. During and after floods, the vegetation

Darling River floodplains can be narrow or over 50km wide. Photo: Floodwaters surrounding the woolshed on Dunlop Station 1886. Photo: Charles Bayliss, 1850 - 1897, National Library of Australia.

Cover image: The Darling River near Bourke. around wetlands and billabongs is crucial for waterbird vary according to bank composition and moisture breeding. Riparian vegetation also protects river water content, bank vegetation, and the speed of water flow. from sediment travelling overland in run-off. Retaining deep-rooted trees is the most effective way to reduce bank slumping along the Darling.

Managing the riparian zone The riparian zone of the Darling River is being better managed through: • fencing to ensure that riparian vegetation can be managed to maintain groundcover and biodiversity. This requires alternative watering points away from the river • upgrading of stormwater systems in major towns, to reduce the amount of pollutants and refuse entering the river • the modification of structures such as road causeways that may affect floodplain flows during floods, affecting off-stream wetland areas • the return of snags to the river, to provide better habitat for native fish Riverbank slumping is a natural process that results in a change in the • the repair of gully erosion adjacent to the river to river’s shape. reduce sedimentation Riverbank slumping is a natural process caused by • removal or stabilisation of old rubbish dumps, a rapid increase and decrease in river flow. As the source of pollution banks of the Darling River are very steep, riverbank • long-term programs to improve native fish slumping has a dramatic appearance. Rates of erosion passage by the installation of fishways at weirs.

The Darling River at Wilcannia. The Western Catchment river systems Like many rivers within the Western Catchment, the Water supports and attracts life. It provides habitat for Barwon-Darling River system originates outside the plant and animal biodiversity and supports commerce Catchment boundary. through industry, irrigation and domestic use. The River is part of a complex system with highly The Western Catchment Management Authority, variable flows. Droughts may be followed by heavy together with local government and the Australian rains which fill thousands of small creeks, flooding the Government, is working with the community to better wetlands and lakes, flowing across the floodplains, manage natural resources: land and vegetation, rivers creating new watercourses and reaching widely and groundwater, cultural heritage and biodiversity. dispersed billabongs and waterholes.

Moonie River Macintyre River

QUEENSLAND BORDER Barwon River Goodooga Mungundi Weilmoringle Wanaaring Enngonia Birrie River Tibooburra Collarenebri

Bokhara R.

Barwon River Walgett Bourke Brewarrina WESTERN White Cliffs Louth SOUTH AUSTRALIAN BORDER SOUTH AUSTRALIAN Darling River

Tilpa

Wilcannia Cobar

Broken Darling River Hill Menindee

References and further information c State of Breckwoldt, R., Boden, R. and Andrew, J. (eds). 2004. The Through the Western Catchment Management Authority 2009 Darling. Murray-Darling Basin Commission, Canberra. Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (November 2009). However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up-to-date and to check currency of the information with the appropriate officer of the Western Catchment Management Authority or the user’s independent advisor. December 2009 ISBN 978-0-7313-3976-1