Australia has the highest diversity and distribution of cracking clays in the world. The overriding problems associated with vertosols in Australia are those of erosion and waterway instability. Vertosols, commonly referred to as black earths, are defined as “clay soils with shrink-swell properties that exhibit strong cracking when dry” (Isbell, 1996) Numerous studies into erosion and waterway stability in vertosol environments were undertaken in the 1980’s, however, most focused on artificial waterways for contour farming and none found any solution to waterway stabilisation. Through community consultation, it was largely agreed upon that typical stream stabilisation measures were inappropriate for these sediments as structures were usually out-flanked or undercut.
The Dry Creek Catchment is a headwater catchment of Oakey Creek, a tributary of the Condamine River. Dry Creek flows west of the Great Dividing Range, with a relatively small catchment covering 40 km2. Land use on the valley floor is a combination of cropping and grazing land. Much of the agricultural land is contoured. Prior to European settlement, it is likely that many of the present day creeks did not exist as a defined channel but more of a grassed discontinuous watercourse with very little surface expression. An increase in catchment discharge, due to clearing for agriculture, and development on the floodplain, has concentrated flow, which has initiated the incision of a defined channel. The floodplains of the lower reaches of the catchment are now being intensely developed for industry. Whereas this has led to an interest in the future behaviour of the incised streams, there is little interest, funding or even established methodology, for waterway stabilisation at this site.
With reduced political interest in waterway health in Australia, research into waterway stability in vertosol soils has all but ceased. More worryingly, those involved in research and implementation in decades past are now retired, and we are at risk of losing vast amounts of knowledge. Here we review previous research and attempts on waterway stabilisation in vertosol soils with reference to Dry Creek and vertosol soils landscapes in general.