GHD | Oceana Gold New Zealand Ltd. | 12552081 | Waihi North Project 26 Figure 13 Mataura Stream and the Ohinemuri River The Mataura Stream catchment has a total area of 6.6 km2 with 85% of this being upstream of the proposed WSFA. The catchment can be described as steep and rugged with the majority of its coverage being native vegetation. The Mataura Stream has a number of small tributaries and flows southeast to join the Ohinemuri River. Baseline flow data for the Mataura Stream has been collected during 2020 and 2021. This data (to date) includes manual flow measurement and the installation of pressure transducers in order to enable collection of continuous flow data. Details on data collection and manual measurements are provided in Appendix A. A synthetic rainfall record for the Mataura Stream catchment was generated based on the rainfall gauge located at Golden Cross. This record was extended based on the observed relationship with the longer Waihi rainfall record. The rainfall data was used to generate a synthetic flow record for the Mataura Stream catchment using an Australian Water Balance Model (AWBM). The manual flow gauging events detailed in WSP 2020 (Appendix A) as well as continuous pressure readings from the installed transducers were used to calibrate the AWBM. Results of the calibration can be seen in Figure 14 and show that the synthetically generated flow record is a fair representation of actual flow over the period of data available.
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