This annual report summarises the operational performance and data integrity from the stations of Christchurch City Council’s (CCC) hydrometric network, as managed by the National Institute of Water & Atmosphere Ltd. (NIWA) for the 2014 calendar year. As at the end of the 2014 period, this CCC network comprises 76 data recording sites in the Christchurch area, consisting of 20 rainfall, 24 water-level, 31 groundwater and 0 miscellaneous stations. These sites are either permanent or project (temporary), most are telemetered via either cellular (GPRS) links or UHF radio. The remainder are manually downloaded or measured on a routine data collection basis (groundwater sites). Some sites are ECan / CCC ‘data shared’ sites or treated as additional datasets from NIWA specific sites, transferred from the NIWA climate database. For the 2014 period, data integrity was again maintained at a high level across most sites, despite interruptions from ‘rebuilding activity’ in the Christchurch area following on from the 2010 - 2011 earthquakes. Total missing record was again kept very low for the 2014 period at 0.71 % of the total hours recorded for all telemetered sites. Such levels of missing record are considered to be very acceptable when compared with New Zealand and international data collection standards. Additional work outside the Hydrometric Network Agreement has also been reported, detailing various projects and tasks that NIWA has assisted the CCC to complete during the year. These have ranged from additional labour orientated duties (flow gauging, new site installations) to sharing of expertise and advice (data handling & archiving, software support, hydrological site design). There are 10 sections that describe the data in this report. (a) Section 2 provides an overview of the weather during 2014 and a commentary on significant rainfall events which occurred during the year. (b) Section 3 outlines the quality assurance checks undertaken on the data and provides statistics on project data capture performance (c) Activities associated with the operation of rainfall, water-level / flow and groundwater sites are described in Sections 5, 6, and 7 respectively. (d) Activities associated with miscellaneous sites including evaporation, temperature (air and water), and any additional sites, are described in Section 8. (e) Proposed work activities that are anticipated by NIWA to be completed in 2015 are described in Section 9. (f) Section 10 details recommendations to further improve the management and operation of the hydrometric network. (g) A summary of any faults experienced during the year is detailed in Appendix 1, and an updated asset list defining the structures, instrumentation and other equipment at each site, is given in Appendix 2.

Water flow data were collected from various river monitoring sites along the catchment water path feeding the Waipori Power Station. Data are presented as daily mean flow (l/s) and flow (m3/s). Three flow recorders are situated at the intake weir in the upper Deep Stream catchment(measuring Deep Stream flow above the weir (site 7444), inflow into the intake flume (site 7443) and flow returned to Deep Stream below the weir (site 7442). A further recorder (site 7445) measures the flow discharged into Lammerlaw Stream at the end of the diversion tunnel and pipeline. This Lammerlaw Stream water flows into Lake Mahinerangi providing additional water for the Waipori generation scheme. During 2008 the Deep Stream diversion was modified to allow water to be diverted to another storage reservoir via a gate structure in the pipeline 2 km before the Lammerlaw Stream Discharge flow recorder (site 7445). A new site (Deep Stream at Downstream Rollergate, site 7446) was installed in this new diversion in November 2008 to measure the flow to the new reservoir and 2 new hydro generation stations. Minimum flow requirements in the lower catchment are monitored at the site Deep Stream at 60 Foot Weir (site 74350). This site is 6 kilometres downstream of the Dunedin City Council Water Department intake on Deep Stream.

Monowai Power Station utilises the outflow from Lake Monowai. This flow is controlled by gates at the lake outlet, and travels several kilometres down the Monowai River before being diverted by a weir into a canal leading to the Power Station and released into the Waiau River. At the diversion weir, a flow is released through the fish-pass and down the Monowai River to maintain a minimum flow. The lake outflow is monitored at site no. 79712 (Monowai at Below Gates). Lake level is recorded at site no. 79713 (Lake Monowai at Hinchey’s Outlet). Flow down the lower Monowai River below the diversion weir is monitored at site no. 79715 (Lower Monowai at Below Weir); this station was installed on 10 April 2003 for resource consent monitoring. The report summarises the data from these sites for the quarterly period – 1 October to 31 December 2014, and in the context of the full record since 1977. Data and outputs cover: Daily Mean levels at Site 79713 Lake Monowai at Hinchey’s Outlet from 1 January to 31 December 2014. Daily mean outflows (m3/s) at Site 79712 Monowai River at Below Gates from 1 January to 31 December 2014. Daily mean inflows (m3/s) at Site 9540, Lake Monowai at Inflow from 1 January to 31 December 2014. Daily mean flows (l/s) at Site 79715, Lower Monowai River at Below Weir, from 1 January to 31 December 2014. Monthly mean levels (lake level in metres, in terms of Monowai datum) at Site 79713 Lake Monowai at Hinchey's Outlet from June 1977 to 31 December 2014. Monthly mean outflows (m3/s) at Site 79712 Monowai River at Below Gates from 1 October 1976 to 31 December 2014. Lake levels at Site 79713, Lake Monowai at Hinchey's Outlet from 1 October to 31 December 2014. Outflows for Site 79712 Monowai River at Below Gates (blue), and Inflows (partial range, green) for Site 9540 Lake Monowai from 1 October to 31 December 2014. Full range inflows for Site 9540, Lake Monowai from 1 October to 31 December 2014. Flow at Site 79715, Lower Monowai River at Below Weir, from 1 October to 31 December 2014. Lake Monowai at Hinchey's Outlet, lake level Lake Monowai at Hinchey's Outlet, water-level distribution from 13 May 1977 to 31 December 2014. Monowai River at Below Gates, outflow from 2 September 1976 to 31 December 2014. Lake Monowai - outflow distribution over the full period of record from 2 September 1976 to 31 December 2014.

Datasets for work undertaken for the Christchurch City Council (CCC) include hydrometric network data (Climate variables, Rainfall, Water level and Ground water levels) from Oct-Dec 2014. Metadata include: 1 Introduction 2 Christchurch climate summary (October – December 2014) 3 Appendix: Maintenance / Fault log Data include: 1 Rainfall monitoring 2 Water-level monitoring 3 Groundwater monitoring 4 Miscellaneous data 5 Additional activities Data are derived from national climate databases and CCC rain gauges. Water-levels are derived from gauges owned by ECan, CCC and NIWA. Ground water levels are measured on either a weekly or fortnightly basis, depending on the site requirements and are measured relative to the CCC datum.

The Waipori Power Scheme uses the outflow from Lake Mahinerangi, passing this flow through four dams and power stations in the upper Waipori gorge. The data and associated report provide flow information in the lower Waipori Gorge below the last (No. 4) Power Station, and below the last Weir (No. 4). The flow recording site (74395) was located three kilometres below the No. 4 Power Station at grid reference H44:802714. The site was shifted upstream on 15 August 2003 to a location 200m downstream of the power station (H44:789715) to enable TrustPower to monitor the flow information by linking the station Program Logic Controller to the site. The flow recording station at H44:777721, site (74398) below the No. 4 Weir was installed on 19 November 2003 for monitoring of minimum flows and ramping rates downstream of the Weir. The following outputs are available from the quarterly data Oct to Dec 2014. Tabulation of daily mean flows at site 74395 for the Waipori at Below No. 4 Power Station from 1 January to 31 December 2014. Full range plot of flows at site 74395 for the Waipori at Below No. 4 Power Station for the reporting period from 1 October to 31 December 2014. A partial range plot (<1000 l/s) to better show the detail of the low flows at site 74395 for the Waipori at Below No. 4 Power Station from 1 October to 31 December 2014. A tabulation of daily mean flows at site 74398 for the Waipori at Downstream No. 4 Weir from 1 January to 31 December 2014. A full range plot of flows at site 74398 for the Waipori at Downstream No. 4 Weir from 1 October to 31 December 2014. A partial range plot (<500 l/s) to better show the detail of the low flows at site 74398, for the Waipori at Downstream No.4 Weir from 1 October to 31 December 2014.