Mapping and characterisation of geomorphology of on-site creeks in and adjacent to the Ranger mine site.

Executive summary

The on-site creeks and waterbodies in and adjacent to the Ranger uranium mine have been mapped and characterised to understand changes to the geomorphology of creeks and billabongs in and adjacent to the Ranger mine over the period from 1950-2016 using remotely-sensed imagery. Specifically, the extent of the Gulungul, Coonjimba and Georgetown billabongs, and associated sandy creek systems and grassy swales, were manually digitised from the imagery and saved in the ESRI ArcGIS Pro environment as a series of individual shapefiles. When the shapefiles were analysed in a GIS environment, little difference was found between the area of the billabong outlines, or the length and number of sandy creeks over time. However, the length of grassy swales was observed to decrease over time. The decrease in swale length is attributed to the subsummation by the Ranger mine and other mine related activities from its construction, through to the cessation of mineral extraction in 2012.

Importantly, the data collected here provide a baseline dataset with which to assess any future changes to the area of the billabongs or length of the creeks or swales after the rehabilitation of the Ranger mine. Specifically, the presence of grassy swales may be used as an indicator of a geomorphically stable landscape. On-going monitoring of grassy swales can provide an early indication of sediment movement from the rehabilitated landform.