Determination of hydrology and erosion model parameters: Natural site adjacent to Pit #1 at ERA Ranger Mine, Northern Territory, Australia, January 1998

1998

Internal Report 270
Bell LSJ & Willgoose GR
Supervising Scientist Division
Department of the Environment

About the report

The current study involved erosion and hydrology data collection and parameter estimation on a 600 square metre field plot adjacent to Pit No.1, at ERA Ranger Mine. Runoff and sediment loss data, resulting from natural rainfall, were collected during the 1996/1997 wet season and utilised to derive parameters for the Field Williams hydrology model, DISTFW; and the overland flow erosion and total sediment loss, sediment transportation models from the landform evolution model SIBERIA.

The kinematic wave and infiltrative loss parameters from DISTFW, were estimated from rainfall and runoff data utilising the non~linear regression analysis package NLFIT. The mean values for the DISTFW parameters were ascertained from eight storm events which had peak discharges in excess of 1 L/s, and a well defined duration. The mean values of the kinematic wave parameters Cr and em, were 4.98 and 1.82, respectively.

A comparison between DISTFW parameters obtained from the current study and the Tin Camp Creek study (comprising two field plots, the Quartz and Mica sites) was widertaken to ascertain if there were any differences in modelled hydrological behaviour. A 95% posterior probability comparison of kinematic wave parameters from eight individual storm events from the current study, and four storm events (compressed into only two sets of parameters) from both the Mica and Quartz sites, highlighted no conclusive trends, even though the Quartz site was considered to be a possible outlier. The comparison of the infiltrative loss parameters between four individual storms from the current study, and the two sets of parameters from the Mica and Quartz sites, highlighted that the Mica site was notably outside the general trend and was considered to be significantly different.