Erskine W, (New South Wales Univ., Kensington. School of Geography)

The Glenelg River catchment has one of the longest records of culturally accelerated soil erosion in Victoria. Following initial European settlement in the 1830s, extensive and severe sheet, tunnel, gully and streambank erosion and numerous mass movements were initiated on the Dundas Tablelands and in the valleys dissecting the Tablelands. This upstream erosion caused the supply of massive volumes of sand to the downstream rivers which resulted in substantial channel and floodplain deposition. The erosive land use phase was succeeded by improved land management and structural soil conservation works in some sub-catchments but not in others during the 1960s. Treated areas now exhibit reduced sediment yields and the downstream rivers have responded by starting to remove the sand supply to the main streams further downstream. Untreated areas still exhibit high sediment yields and the downstream rivers are still actively storing sand. The main streams (Glenelg and Wannon Rivers) are currently being supplied with sand from both the treated and untreated tributaries. Such out-of-phase behaviour between catchments and streams is to be expected, due to the lag time necessary to excavate the sand temporarily stored in the channel during the previous erosive land use phase. It will be many years before the rivers in the Glenelg catchment recover, despite the completion of extensive soil conservation works.