HSIE K–12

WARNING – Aboriginal and Torres Strait Islander viewers are warned that the following video may contain images and voices of deceased persons.

Narrator

The Rocky River and Clarence River, like other rivers, are powerful transformers.

[Screen reads – Focus question: How do streams, creeks and rivers shape and change our landscape?]

They have shaped most of the landscape we see today over thousands of years. Rivers erode and transport large amounts of sediment from one location to another, eventually depositing the eroded material downstream, creating a range of unique landforms.

Rivers naturally flow from upland areas to a mouth in the lower areas following the force of gravity. As a river gets closer to the mouth, it generally becomes larger, deeper and wider. Small creeks receive water from rain on the land nearby then flow down into the river, adding to the volume of water being transported. The area that supplies water to the river is commonly referred to as a catchment area. The ridges that divide one catchment from another is called a watershed.

[Screen reads – Watershed. Ridges that divide one catchment from another]

The Australian landscape is composed of many catchment areas divided by watersheds. Here you can see a map showing all the rivers across Australia. Here you can see another map which shows Australia divided into its major catchment areas. Close to the river source, the river channel is often narrow and deep. In this area of a catchment the water travels fast and erodes the landscape which means you are more likely to see v-shaped valleys, rapids and waterfalls.

The middle and lower courses of rivers are often characterised by depositional landforms. This is where the water speeds slow down and the sediment carried from upstream is deposited. Floodplains are the flat area of land on either side of the river. Floodplains are fascinating to observe because over time they change continually, shifting river paths. Along floodplains, you will observe the river meandering in bends that make it look like a large snake.

The water naturally erodes the sediment and other materials from the outer beds of the river where the water speeds up and deposits on the inside of the banks where the water slows. In this way, the river slowly shifts course. The catchment divides New South Wales and Queensland by its watershed, west of Bonalbo in the Border Ranges. The Clarence River flows south and is joined by 24 tributaries including the Rocky River. This unit of work focuses on the Rocky River at Tabulam. The Clarence River is approximately 394 kilometres in length and broadens considerably at Grafton and at its mouth in Yamba.

[Screen reads – Focus question: Why is the Clarence River Catchment an important riverine environment?]

The Clarence River catchment is a rich and diverse riverine environment. Many people rely on the river system for economic and recreational purposes. It is home to diverse flora and fauna. The fresh water supports important populations of freshwater fish including the Eastern Freshwater Cod and Australian Bass. Loss of this important freshwater ecosystem will have severe cultural, social and economic consequences to the entire region.

List of sources and Acknowledgements:

1. Image – Australian Rivers. Retrieved from www.ga.gov.auExternal link
   
2. Image – Australian Drainage divisions and River Basin Boundaries. Retrieved from www.ga.gov.auExternal link
3. Video – Drone footage of The Everlasting Swamp. We would like to thank The Everlasting Swamp National Park and Jessica Robertson Photography and Design for contributing their beautiful drone footage
4. Narration – Voice over by Melissa Ellis, Southern Cross School of Distance Education
5. Acknowledgment – We wish to thank Father Pop Harry Walker, Annabelle Walker, Roy Bell, Jubullum Local Aboriginal Land Council, Steve Walker, Marty Walker, David Foley, Upper Clarence River Landcare, Terry Moody, Steven Ross, Frederick Ellis

]End of transcript]