Hydrology and suspended sediment transport in the Gulungul Creek catchment, Northern Territory: 2006-2007 wet season monitoring

2007

Internal Report 531
Moliere DR, Evans KG & Saynor MJ
Supervising Scientist Division
Department of the Environment, Water, Heritage and the Arts

About the report

Gulungul Creek is a small left bank tributary of Magela Creek. The Gulungul Creek catchment contains part of the Energy Resources of Australia Ranger mine tailings dam and could potentially receive sediment generated as a result of the removal and rehabilitation of the tailings area. Hence it is important that the hydrology and sediment transport characteristics in the Gulungul Creek catchment are investigated before rehabilitation at the mine site occurs to establish pre-rehabilitation reference conditions. Continuous rainfall, runoff and mud (<63 mm and >0.45 mm fraction) concentration data collected at gauging stations on Gulungul Creek during 2006–07 are presented in this report.

Total annual rainfall and runoff observed during 2006–07 were the highest recorded within the Gulungul Creek catchment since recordings began in 1971. This is largely attributed to a 3-day period of exceptionally high rainfall which occurred between 27 February and 2 March 2007 resulting in the highest flood levels that have been recorded within the catchment.

An assessment was also made of the impact of Cyclone Monica, which occurred on 25 April 2006, on stream suspended sediment concentration within Gulungul Creek during 2006–07. A combination of an event-based Before-After-Control-Impact, paired difference design (BACIP) approach and a relationship between event mud load and corresponding event runoff characteristics showed that the sediment transport characteristics within the catchment were not significantly different to previous years.