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A device to assist
in stabilising the bank |
Streambank erosion is a dynamic and natural process as streams meander across the landscape.
Since European settlement of Australia, however, in many places the rate of streambank erosion has increased markedly. There are two primary reasons for this increase. The first is extensive clearing of deep-rooted, natural vegetation from catchments for agricultural and urban development. This has resulted in rainfall moving off the land surface at a much faster rate.
These increased flows put pressure on stream channels that can no longer contain flood peaks, and bank erosion (as well as bed erosion) is one result. The second factor is the widespread removal of native riparian vegetation from along streambanks, either through deliberate clearing for development, or through the combined effects of stock grazing and fire.
The removal of large, woody debris (de-snagging) in many streams, sometimes to assist navigation and transport, and sometimes in the belief that this would reduce flooding, has also contributed to making streambanks unstable. Both these activities have weakened the ability of streambanks to resist the erosive forces of increased flood flows and resulted in eroding streambanks becoming a common feature in Australian landscapes.
Streambank erosion often involves the loss of valuable agricultural and recreational land. As the banks collapse or erode into the stream and are washed away, sediment and nutrient loads increase and water quality is reduced. Expensive infrastructure, such as roads, bridges and buildings, may be threatened by accelerated streambank erosion.
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Acknowledgement
Information used in compiling this page was sourced from the Land and Water Australia website located at www.rivers.gov.au and form their publication titled: