Discontinuous gullying of the Tea Tree Rivulet, Buckland, eastern Tasmania

Abstract

The recent development of discontinuous gullying appears to be largely due to clearing of the natural floodplain vegetation in the first half of the 19th century although climatic factors may have contributed in a minor way. Rate of headcut migration is related to the frequency of flood flows. which in turn is a function of the frequency of occurrence of large rains. The upward trend in the number of small rains at least since 1915 is thought to have reduced sediment yields through its beneficial influence on the catchment vegetation and may be another factor favouring acclerated erosion of the floodplain. In future studies of unstable stream channels in alluvial deposits a distinction should be made between continuous trenches and discontinuous gullies. When discussing the effect Of vegetation changes on stream behaviour a distinction should always be made between the vegetation of the catchment slopesandi that of theffnodplaln or alluvial fan in which the channel under study is situated since the same change in both may have opposite effects on the behaviour of the stream.