Do suspended sediment and bedload move progressively from the summit to the sea along Magela Creek, northern Australia?
- 1Hydrological, Geomorphological and Chemical Processes Group, Environmental Research Institute of the Supervising Scientist, GPO 461, Darwin NT 0801, Australia
- 2School of Environmental & Life Sciences, The University of Newcastle, PO Box 127, Ourimbah NSW 2258, Australia
- 3Research Institute for the Environment and Livelihoods, Charles Darwin University NT 0909, Australia
- 4Revegetation and Landscape Ecology Group, Environmental Research Institute of the Supervising Scientist, GPO 461, Darwin NT 0801, Australia
- 5Mining Technology Group, School of Engineering & Information Technology, Charles Darwin University, Darwin NT 0909, Australia
Keywords: Turbidity, sediment yields, sediment discontinuities, natural sediment traps, sediment budget
Abstract. Soil erosion rates on plots of waste rock at Ranger uranium mine and basin sediment yields have been measured for over 30 years in Magela Creek in northern Australia. Soil erosion rates on chlorite schist waste rock are higher than for mica schist and weathering is also much faster. Sediment yields are low but are further reduced by sediment trapping effects of flood plains, floodouts, billabongs and extensive wetlands. Suspended sediment yields exceed bedload yields in this deeply weathered, tropical landscape, but the amount of sand transported greatly exceeds that of silt and clay. Nevertheless, sand is totally stored above the topographic base level. Longitudinal continuity of sediment transport is not maintained. As a result, suspended sediment and bedload do not move progressively from the summit to the sea along Magela Creek and lower Magela Creek wetlands trap about 90.5% of the total sediment load input.