Woody debris is a natural component of rivers

As the trees growing alongside a stream or river age, die and decay, large branches and sometimes even the whole trunk, can fall or topple onto the streambank or into the channel itself. There is increasing evidence that before European settlement, most rivers in Australia had a large amount of this woody material, usually known as large woody debris (LWD) along their banks and within their channels. Natural events such as major floods, bushfires and severe frost are likely to have contributed to the amount of LWD found within rivers. To the early settlers, LWD was often a nuisance. It made access to streams by stock difficult, and large snags within rivers were a major hazard to transport and navigation at a time when waterways were a major route for moving goods and people. It was generally thought (often incorrectly, as we now know) that LWD blocked the channel and caused additional flooding at times of peak flow. As a result, particularly in southern Australia, millions of snags were removed from streams and usually piled on the bank and burnt.

Natural load of LWD in the lower Campaspe
River, northern Victoria. In undisturbed systems
LWD is protecting the river bank.
Photo Ian Rutherfurd.

The full fact sheet is available in Adobe Acrobat format:

   Fact Sheet 7 - Managing Woody Debris in Rivers (facts07.pdf, 700Kb)

Topics covered

• Why is LWD important?
• Effects of LWD on flooding
• Does LWD accumulate on bridges?
• LWD and bank erosion
• Managing LWD
• For more information

This Fact Sheet is the seventh in a series dealing with the management of riparian land.