AbstractThis research aims to develop an understanding of riparian erosion process, form and cause along the Victoria River, Northern Territory. The Victoria River District (VRD) is located in the semi-arid tropics of Australia, where cattle grazing is the primary land use. The Victoria River riparian zone is intersected by erosion features. The heavily stocked mid-catchment is particularly degraded and suffering severe erosion. The process, form distribution and cause of riparian erosion in the VRD are explored via the study of the environmental setting and land use history.
The geomorphological and hydroclimatological setting are the major factors contributing to both the natural and enhanced erosion process. Three forms of riparian erosion are recognized throughout the catchment: sheet, gully, and gully complex. Gully complexes are described in detail and involve several erosional processes. The naturally occurring flood drainage channels (FDCs) co-evolved during floodplain development, while runoff processes are active in the outer feature which is characterized by a well defined scarp and active badlands. Analyses of air photos show that FDC features along the study reach always develop into gully complex features. Some gully complexes were found to have retreated headward up to 50m in the past 60 years. Gully complexes that did not exhibit headward retreat were found to contain badlands that increased in depth, and the depth of the scarp also increased.
The settlement of the VRD, and introduction of cattle to the region c.120 years ago, has allowed for the expansion of naturally occurring FDCs, into gully complexes. High intensity rainfall events, flooding and susceptible soils make much of the VRD vulnerable to naturally high erosion rates; the removal of vegetation by cattle has initiated additional erosion processes. The results indicate that FDCs existed prior to European settlement, however badlands have formed at the heads of FDCs after the introduction of cattle. FDC development was determined to be an inherent feature of the VRD landscape. Badlands have developed as a result of the introduction of cattle to the region.
|Date of Award||2010|
|Supervisor||Guy Stuart Boggs (Supervisor), Robert Wasson (Supervisor) & Michael Douglas (Supervisor)|