Internal Report 646
A trial rehabilitation landform was constructed at Ranger uranium mine in early 2009 for the purpose of charactering vegetation establishment, rates of erosion and contaminant transport under different surface treatments and vegetation establishment strategies. To support this research, four erosion plots were designed and constructed by eriss (project RES-2009-011) to continuously monitor, across the different regimes: rainfall; associated surface water runoff; solute; and sediment transport (suspended sediment and bedload). In this regard, the time-series data for rainfall and runoff are to be used in conjunction with other measured variables to: a) determine physical erosion rates in relation to rainfall and surface water discharge; b) provide calibration input data for predictive geomorphic computer modelling of proposed landform designs (Lowry et al 2015); and c) determine contaminant loads, pathways, and sedimentation sinks.
To meet these requirements, it was necessary that the hydrology dataset undergo rigorous screening to provide assurance that data were suitable for intended purposes. To address issues in data quality, a separate report has been written for each plot and selected periods (as required) with two reports, for Erosion Plots 1 and 2, reported so far. In this regard this report assesses quality of the Erosion Plot 1 (EP1) hydrology dataset from 01‑09‑2009 to 31‑08‑2015, covering a period of 6 water-years, and describes the methods used to check and correct these data. Other physico-chemical variables were also monitored at EP1 from 2009 to 2014 but are not the subject of this report.
This assessment found a site-specific problem with excess runoff, believed to occur from off-site surface water flowing across the plot containment (i.e. boundary overflow) during periods of high rainfall. The methods developed to identify and correct for these and other issues, have minimised errors in the dataset. It is considered that the applied corrections have resulted in a complete, quality coded hydrology record suitable for further analysis. An important conclusion is that in future years of data acquisition, any event with rainfall greater than 30 mm should be checked for overflow error at this monitoring site.