Monitoring of gully erosion at ERA Ranger uranium mine Northern Territory, Australia, January 1998

1998

Internal Report 274
Bell JRW & Willgoose GR
Supervising Scientist Division
Department of the Environment

About the report

As part of the proposed rehabilitation at Ranger Uranium Mine, ERARM, investigation into the long term erosional stability of the final design landforms is currently being conducted.

The steep batter slopes of the proposed landform are considered highly susceptible to erosion, with previous investigations highlighting possible problems caused by the development of gullies through the containment structure.

This project constitutes one aspect of this assessment process.

The aims of this project were to:

  • Firstly, initiate a gully on the steep batter slopes of the Northern Waste Rock Dump.
  • Secondly, to monitor the development of the gully, and hydrology of the gully catchment.

These two components constituted the field trial and were conducted with the assistance of the Office of the Supervising Scientist, eriss and ERA Ranger Mine.

  • The third objective, was assessment of the capability of the landform evolution model SIBERIA to predict the extent, depth and width of gullies formed on the steep waste rock slopes,
  • and finally, by comparison between observed and predicted landforms, ascertain dominant erosional processes, and assess implications of additional erosion modules on these predictions.

SIBERIA was adapted to represent the batter - gully catchment study site, and validated through direct comparison between predicted and observed landforms. Modification of the homogenous initial landform to incorporate heterogeneity, increased catchment outlet width, and implementation of rudimentary armouring module, have encapsulated the dynamism of the development process observed on site.

Depths of erosion are comparable to those observed, and behaviour of gully development is mimicked by model simulations shown here.