GHD | Oceana Gold (New Zealand) Ltd | 12552081 | Waihi North 18 . Figure 2.2 Wharekirauponga Portal Location 2.2 Surface water Where groundwater is in hydraulic connection with surface water, the effects of groundwater-related activities (such as construction dewatering on allocation limits) have been considered as part of this hydrogeological assessment. An overview of the hydrology is provided below, with detail provided as required in the respective technical assessments (Sections 3 - 6). 2.2.1 Regional hydrology Waihi is located in the upper catchment of the Ohinemuri River, which has a total catchment area of 290 km2. The eastern parts of the upper catchment consist of predominantly flat farmland. Numerous tributaries join the Ohinemuri River as it flows west, with the upper catchments becoming steep and forested further inland. The Ohinemuri River then flows through the Karangahake Gorge prior to joining the Waihou River near Paeroa. OGNZL operates flow gauges along key surface water bodies (Figure 2.1) as part of daily compliance monitoring for the existing mining activities: – Frendrups gauge: Measures flow on the Ohinemuri River between the mine site Processing Plant and northern stockpile. The river catchment at this location is approximately 50 km2, with flow ranging from 15,300 – 3,180,000 m3/day and a long-term median flow of 75,400 m3/day. For this assessment, a median river flow of 63,200 m3/day was adopted for the period that coincided with the site investigations (October 2017 – April 2020). This is conservatively lower than the long-term median provided above.
RkJQdWJsaXNoZXIy MjE2NDg3