Monthly Data (commencing Jan 1989) comprising physical measurements, chemical and bacteriological analyses, and periphyton observations from 77 National River Water Quality Network (NRWQN) sites for the purpose of environmental assessments and monitoring of long term trends. The NRWQN has been funded up until June 2011 by the Foundation for Research, Science & Technology (FRST) through NIWA's Nationally Significant Database: Water Resources & Climate programme. Commencing July 2011, continuation is via NIWA Environmental Information/Monitoring programme core funding.

NIWA has published a lake chart for every lake in New Zealand that can be surveyed, except for Lake Dunstan. The charts are of various scales that are determined to be the most appropriate for the size of the lake. The compilation of bathymetry from echo-sounding surveys with publication dates ranging from 1966 to 1989. This dataset also contains newly surveyed bathymetry using multibeam information. New data as and when available shall be added to this dataset. Some of the lakes may have more than one set of bathymetry files. The earlier one could be from the period 1966 to 1989 and the new information from recent surveys undertaken for comparison purposes.

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.

A morphological model of Lake Dunstan was developed and used to better predict the future development of the sediment delta in the combined Kawarau/Dunstan Arms, to assess the change in sediment outflow quantity and composition over time and to reassess flood profiles based on future projections of the lake bed. A one-dimensional morphological model of Lake Dunstan has been constructed using the US Bureau of Reclamation’s SRH-1D modelling package. Steady-flow backwater simulations were run using 50 year and 100 year beds output from the 100 year projection simulation. These predictions are best estimates based on current knowledge but are subject to uncertainties in water inflows, sediment supply rate and gradation, and in key parameters such as channel roughness. We recommend continued monitoring of water levels and turbidity at current monitoring sites, along with regular survey of cross-sections and surface grain-size to provide ongoing data to update these predictions. In addition we recommend re-running the morphological model at 10 year intervals to update the estimates of projected flood levels. Several cross-section survey datasets have been used in this study. These datasets were all supplied by OPUS, and were sourced from the MIKE-11 model cross-section database. The representations of cross-section survey data within the SRH-1D model should therefore be identical to the survey data used in previous modelling studies using the MIKE-11 model. Using the calibrated model a 100 year projection simulation was run. Key predictions (from a February 2014 base) are: (a) The thalweg level at the Ripponvale gauging station will rise 2.6 m over 50 years and 4.7 m over 100 years with the rise occurring at a constant rate of 0.035 m/year over the 100 year period of the simulation. (b) A bed thalweg rise of 13 m at the Kawarau/Clutha confluence over the first 10 years, as the sediment tipping point passes the confluence, followed by a steady rise of 0.05 m/year over the remaining 90 years of the simulation. (c) The sediment outflow at Clyde Dam increases over time from an average of 168 kt/year over the first 20 years to 518 kt/year over the last 20 years (i.e. for year 80-100). Correspondingly, the trap efficiency for Lake Dunstan reduces from a 20 year average of 91% for year 0-20, to 72% for year 80-100. (d) The sand content of the outflow increases from 0.4% to 3.3% for years 0-20 and 80-100, respectively, and is almost completely very fine sand grade. We note, however, that it is likely that operation of the bottom sluice of the dam would lead to significantly higher outflows of sand than predicted by the model, as the model does not provide any representation of where vertically or horizontally in the cross-section the outflow occurs. Steady-flow backwater simulations were run using 50 year and 100 year beds output from the 100 year projection simulation. Key results are: (e) The flood level at Ripponvale for a 3200 m3/s flow at Clyde Dam is predicted to be RL 202.92 after 50 years and RL 204.53 after 100 years (c.f. RL 200.49 currently). (f) For the same flow at Clyde Dam, and for a headwater level at Clyde Dam at the design flood level of 195.1 m, the flood level at the Kawarau/Clutha confluence is predicted to be RL 198.95 m after 50 years and RL 200.76 m after 100 years (c.f. RL 195.34 m currently). (g) Flood levels in the Upper Clutha Arm at the Cromwell end of the lake are just 0.05 m higher than at the Kawarau/Clutha confluence for a 3200 m3/s total flow.

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.

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.

Locations and descriptions of New Zealands glaciers as at 1978 (South Island) and 1988 (Mt Ruapehu). A full description of the inventory is published in: Chinn, T. J. (2001). "Distribution of the glacial water resources of New Zealand." Journal of Hydrology (NZ) 40(2): 139-187. This paper is available at: http://www.hydrologynz.org.nz/downloads/20071015-094857-JoHNZ_2001_v40_2_Chinn.pdf

The National Rivers Water Quality Network (NRWQN) has never included suspended particulate matter analyses in all 26years of its existence, although optical proxies (visual clarity; turbidity) are measured routinely. The purpose of this add-on to the NRWQN was to 'calibrate' those optical proxies to total suspended sediment (TSS) in particular rivers - to confirm the original supposition in design of the NRWQN that routine, ongoing measurement of TSS would be too expensive and not sustainable when most visits to sites intercept rivers in baseflow when TSS is relatively low and sediment flux very low. The opportunity was taken during this add-on also to measure organic content of SPM in rivers (as volatile suspended sediment; VSS) and the nutrient (N and C content) of this organic matter (particulate organic carbon, POC; particulate organic nitrogen, PON). The TSS data in the dataset has already been published (along with correlating NRWQN data) by Davies-Colley et al. (2014) and Ballantine et al. (2014). [Ballantine, D.J.; Hughes,A.O.; Davies-Colley,R.J.(2014).Mutual relationships of suspended sediment, turbidity and visual clarity in New Zealand rivers. Sediment Dynamics from the Summit to the Sea Proceedings of a symposium held in New Orleans, Louisiana, USA,11–14 December 2014)(IAHS Publ. 367, 2014). doi:10.5194/piahs-367-265-2015 Davies-Colley, R.J.; Ballantine, D.J.; Elliott, S.H.; Swales, A.; Hughes, A.O.; Gall, M.P. (2014).Light attenuation - a more effective basis for the management of fine suspended sediment than mass concentration? Water Science and Technology 69(9):1867-74. doi: 10.2166/wst.2014.096.]

This core-funded research project aimed to map river reaches that gain and lose water to, and from, the groundwater system from two regions of New Zealand (Southland and Otago). A survey of river reaches that lose and gain flow in these regions of New Zealand was conducted at Environment Southland (ES), and Otago Regional Council (ORC) with key hydrologists, groundwater scientists and ecologists to record their knowledge of the locations of flow losing and gaining reaches on rivers and streams in their region. Following these interviews, the information was then transferred to a GIS layer to enable mapping of losing and gaining reaches in Southland and Otago. This work could serve as a platform for groundwater related research or engineering by NIWA in New Zealand.