- Title
- Hydrology and bedload transport relationships for sand-bed streams in the Ngarradj Creek catchment, northern Australia
- Creator
- Erskine, W. D.; Saynor, M. J.
- Relation
- Journal of Hydrology Vol. 483, p. 68-79
- Publisher Link
- http://dx.doi.org/10.1016/j.jhydrol.2013.01.002
- Publisher
- Elsevier BV
- Resource Type
- journal article
- Date
- 2013
- Description
- Rainfall, discharge and bedload were measured at three gauging stations (East Tributary, Upper Swift Creek and Swift Creek) in the Ngarradj Creek catchment at Jabiluka, Northern Territory, Australia. Hand-held, pressure difference, Helley-Smith bedload samplers were used to measure bedload fluxes for the 1998/1999, 1999/2000, 2000/2001 and 2001/2002 wet seasons. Rainfall is strongly seasonal over the Ngarradj Creek catchment, being concentrated in the wet season between November and April. Mean annual point rainfall between 1998 and 2007 for the water year, September to August, inclusive varied over the Ngarradj Creek catchment from 1731 ± 98 mm (SE) to 1754 ± 116 mm. Between 190 and 440 mm of rainfall are required before streamflow commences in December in most years. Streamflow persists until at least April. Mean annual runoff, as a percentage of mean annual rainfall, decreases slightly with increasing catchment area. Bedload ratings were calculated for four data sets. Significant bedload ratings were defined as those that were not only statistically significant (ρ ⩽ 0.05) but also explained at least 0.60 of the variance in bedload flux. For the three stations, twenty-three bedload ratings complied with the above criteria. Sixteen equations were accepted for East Tributary, four bedload ratings were accepted for Upper Swift Creek and three bedload ratings were accepted for Swift Creek. Significant bedload ratings were established between bedload flux and discharge, unit bedload flux and discharge, transport rate of unsuspended bedload by immersed weight per unit width and time and both unit and excess unit stream power, and finally, adjusted submersed bedload weight and both unit and excess unit stream power for raw and log₁₀-transformed data. ‘Censored data sets’ were compiled for Upper Swift Creek and Swift Creek to include only bedload fluxes measured when there was no apparent scour or fill so that there were no changes in sand supply from the catchment (i.e. equilibrium conditions). Bedload sediments are similar at all sites. There is little difference in grain size statistics between wet season bedload and dry season bed material. The differences which were significant suggest that most of the bed material is transported as bedload during the wet season. Size selective transport occurs at all three gauging stations with bedload being better sorted than bed material and the coarsest fraction (Cobble gravel) is mobile only during extreme events.
- Subject
- bedload flux; unit stream power; bedload sediment ratings; size selective transport
- Identifier
- http://hdl.handle.net/1959.13/1300336
- Identifier
- uon:20046
- Identifier
- ISSN:0022-1694
- Language
- eng
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