Appendices 5-13 - Nautilus Cares - Nautilus Minerals

Stochastic modelling was carried out for 100 samples using random commencement time periods
over a calendar year from late August 2006 to late August 2007. The model was performed on each
discharge scenario for a continuous discharge including the additional surface waters used for
predilution, over an 8 day period. Deep sea water currents and some bathymetry data were
provided by the client and used in this modelling.
2.3 Deep Sea Temperature and Current Data
Modelling was performed using the ADCP-A current data (provided by the client) dated from
20/8/2006 to 25/8/2007. This ADCP-A was a 300kHz ADCP deployed on top of the Solwara 1
mound (at 1,500 m depth) looking upwards.
This current data was analysed and entered into the modelling system. The analysis of this year
long current data at 6m above the mound is summarized in Figure 2.1 (as a current rose) and
corresponds to the approximate location of the operation. Figure 2.1 shows that the currents are
relatively weak at these depths. Figure 2.1 also shows that flow directions are typically north-
northeast and westsouthwest, which corresponds to the tidal axis at these depths. The median
current speed just above the mound is only 7 cm/s (0.07 m/s), the maximum speed recorded at this
depth was 35 cm/s, however only 5% of the current speeds exceeded 15 cm/s.
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