Literature Review: Vegetation Effects on Channel Morphology and Bank Stability – for use in designing catchment works

Abstract

This literature review examines the effects of vegetation on channel morphology and bank stability. It briefly describes geomorphic processes in relation to stream channel morphology and evolution and summarises the role of riparian vegetation in channel form stability and associated instream water quality. The following points are highlighted as relevant areas of research, knowledge gaps and proposed research questions to inform the design of catchment works and long term investment of significant funds in stream rehabilitation: • Studies of pre and post-European vegetation extent studies have shown approximately 43% of native vegetation remains in SEQ following European settlement. These data also show rainforest and vine thicket that was present in moist gullies and riparian zones was reduced to a third of its original extent, post-European settlement. • Channel morphology is strongly influenced by vegetation composition and several studies across Australia have shown a sensitivity of channel width to different forms of riparian vegetation. • There is still disagreement in the literature as to the most appropriate vegetation composition to be used for channel stability management. • The effect at the catchment scale that riparian revegetation has on channel morphology, sediment and nutrient export, water yield and aquatic ecosystem health is largely unknown. • Knowledge gaps include specific revegetation techniques for sub-tropical regions; appropriate riparian zone width and length; vegetation species; species composition on a transverse and longitudinal profile; and planting techniques for flood prone areas and following catastrophic channel changes. • Monitoring of management action effectiveness and efficacy is untested in sub-tropical catchments and the design and evaluation of monitoring programs on a catchment scale is a significant knowledge gap.