Letter Report No: CR 2015/214 LR Project No: Not Applicable

25 November 2015 Wairakei Research Centre 114 Karetoto Road

RD 4 Taupo 3384 Private Bag 2000 Taupo Mail Centre Taupo 3352 T +64-7-374 8211

F +64-7-374 8199 www.gns.cri.nz

Dear Stakeholder

Re: Outputs from GNS Science Hydrogeology Research programmes

This document reports on GNS Science’s hydrogeology-related research outputs for the period July 2014 to October 2015. A glossary of acronyms is included in Appendix 1.

The aim of our hydrogeological research is to answer the high-level question: How can we improve the sustainable management of, and economic returns from, New Zealand’s groundwater resources?

Our hydrogeology research activities are undertaken as part of four different research programmes, funded by the Ministry of Business Innovation and Employment (MBIE):

• Tracer Validation of Hydrological Systems (TVH): This programme aims to improve groundwater models by calibration and validation using hydrochemical, temperature and age tracer data. Case study areas are in the Bay of Plenty, Wellington and Southland regions. Contact: [email protected]. • Smart Aquifer Characterisation (SAC): This programme aims to develop a suite of highly innovative methods for characterising New Zealand’s groundwater systems faster and/or less expensively than using traditional methods. Contact: [email protected]. • Groundwater Resources of New Zealand (GWR): This is GNS Science’s core- funded hydrogeology research programme. The programme objectives include the National Groundwater Monitoring Programme (NGMP), characterisation of soil and groundwater systems, water-land policy and economics, biological products, and application of isotopic tools for understanding the dynamics of hydrologic systems. Contact: [email protected]. • Ka Tu Te Taniwha – Ka Ora Te Tangata (NRW): The programme aims to understand the impacts of development in the Awahou groundwater catchment to ensure the health and wellbeing of the Ngati Rangiwewehi people. This is programme is co-funded by GNS Science, Ngati Rangiwewehi, and Bay of Plenty Regional Council. Contact: [email protected].

Page 1 of 20 Institute of Geological and Nuclear Sciences Limited

In addition, GNS Science receives funding from regional councils and from the National Institute of Water and Atmospheric Research (NIWA) “Waterscape” programme that allows us to contribute our groundwater science to water resource characterisation and management.

We have structured our research into five second-level questions (Table 1), each of which is addressed through specific activities. Each of our specific research activities is presented in relation to the eight critical research issues defined by the Groundwater Forum (GWF)1. For your convenience, we have listed all the outputs in Table 2, where individual outputs can be directly accessed by clicking on the hypertext.

Table 1: Relationships between GNS Science hydrogeology research questions and GWF critical research issues. “Direct“ indicates that the answer to the GNS Science research question is essential to address a GWF critical research issue. “Indirect” indicates where the answer to the GNS Science research question brings some elements to address a GWF critical research issue.

1 Williams, H. (2013). Groundwater Science Needs & Communication of Research Deliverables. Elemental Consulting Report Env-2012-1.131 p.

Page 2 of 20

GNS Science

Table 2: GNS Science Hydrogeology research questions and science outputs. (In the electronic version of this report, click on each question or output to link to it) Hydrogeology Department Research output research question (July 2014 to October 2015)

1. What are the 3D geological model of the Waikato River catchment. hydrogeological and Machine-learning algorithms to map 3D surficial aquifers fast. structural characteristics of New Zealand's aquifer Hydrogeological interpretation of Airborne Electromagnetic data in Otago. systems? New Zealand Aquifer Map and Groundwater Atlas.

National estimates of evapotranspiration and rainfall recharge. Rainfall recharge: toward a standard operation procedure for measurements. Temperature sensing coupled with radon measurements for model calibration. 2. What are the fluxes of A new method for baseflow separation. water into, out of, and through New Zealand's Tritium application in the Australian ‘Super science’ catchment study. aquifers? Parameter estimation to optimise hydrochemical characterisation. The role of bedrock groundwater in headwater catchments, Maimai. A new SMART method to sample shallow groundwaters – Push Drill. New software to investigate the effect of regional groundwater flow on temperature distribution in a geothermal reservoir.

Baseline trends. Understanding the relationship between groundwater phosphorus 3. What are the fluxes of key concentrations and land use. substances into, out of, and Novel age tracers: radon and halon. through New Zealand's aquifers? NGMP data. Isotope methods for tracking the sources and fate of dissolved inorganic nitrogen. Production scenarios under climate change.

Loose groundwater-surface water coupling of a regional scale flow model. The use of groundwater age and hydrochemistry to understand source and fate of nutrients, Lake Rotorua. Climate signals in New Zealand groundwater. 4. How have/will human activities, climate change Climate signals from ice cores. and other pressures affect The Geothermal and Groundwater database activities. New Zealand's groundwater resources? Groundwater data portal development update. Web-based data portal for the Awahou catchment under development. Downloadable groundwater tools usage, GNS Science website. “Earth Beneath Our Feet” website.

Earthquake Hydrology: Seismic Pumps or Broken Pipes.

Other GNS Science Did artesian groundwater contribute to liquefaction and lateral hydrogeology-related research spreading damage? (Natural Hazards Research Platform funded). projects Hutt River toxic Algae blooms. Pacific Island drinking water security.

Page 3 of 20

GNS Science

Hydrogeology Department research question 1: What are the hydrogeological and structural characteristics of New Zealand's aquifer systems?

Output 1.1: 3D geological model of the Waikato River catchment (Waikato Regional Council funded)

GNS Science is part of a multi-agency project to help improve the health of the Waikato and Waipa Rivers and their sub-catchments. The aim of the multi-year project, called Healthy Rivers: Plan for Change- Wa Ora: He Rautaki Whakapaipai, is to reduce the problematic amounts of sediment, bacteria, nitrogen and phosphorus entering waterways. The area encompasses land extending from Lake Taupo to the Tasman Sea – an area of over a million hectares. This highly productive area of New Zealand contributes a significant portion of our land-based exports and 40% of our electricity generation through hydro and geothermal. The ambitious project is unique in its size and scope, and that it is a partnership between the Waikato Regional Council and five river iwi partners, with a Technical Leaders Group to provide strategic direction.

Our role is to characterise the groundwater in the two catchments. This includes three- dimensional geological modelling of the three zones in the catchment – upper Waikato, Waipa, and lower Waikato. The models identify factors important to the flow of groundwater such as aquifers and sub-surface layers that influence flow rates. Our modelling also shows the length of time water resides in various catchments. We also summarised important properties of the aquifers including water quality and links between ground and surface water. Information from the project will provide a more accurate picture of the current status of the rivers and the estimated time it will take to make improvements due to the various mitigation measures. The information will be used to develop objectives, policies and methods in the regional plan to manage the four contaminants and restore and protect the health and wellbeing of the two rivers and their catchments.

White, P.A.; Tschritter, C.; Rawlinson, C.; Moreau, M. In review. Groundwater resource characterisation in the Waikato River catchment for the Healthy Rivers Project, GNS Science Consultancy Report 2015/95.

Output 1.2: Machine-learning algorithms to map 3D surficial aquifers fast (GWR funded)

A computationally-intelligent approach for determining hydrostratigraphic units has been developed by combining scale-dependent geophysical and hydrogeologic data. This approach is based on examining the relationships between a multitude of different data sets. Once a data relationship model is validated, it is possible to add new data (e.g., real-time measurements) as fast as measurements are presented to the algorithms. This advance also means that multiple data sets can be combined for integrated interpretation of 3D data. This knowledge provides a unified approach for conceptualizing groundwater models, initial starting parameter values and geostatistical constraints for improved numerical groundwater model calibration.

Friedel, M.J.; Esfahani, A.; Iwashita, F. Accepted. Toward real-time 3D mapping of surficial aquifers using a hybrid modeling approach, Hydrogeology Journal. Friedel, M.J. In review. A computationally-intelligent approach for determining hydrostratigraphic units, Journal of Hydrology.

Page 4 of 20

GNS Science

Output 1.3: Hydrogeological interpretation of Airborne Electromagnetic data in Otago (SAC funded)

A robust data interpretation using machine-learning algorithms is currently being trialled to map 3D hydrogeological properties over large areas utilising existing airborne electromagnetic (AEM) data in Otago. The aim of this interpretation is to map hydrostratigraphic units down to ~100 m at a starting resolution of 1 m close to the surface (larger uncertainty at depth) by utilising AEM data in conjunction with all available ground- truthing data: QMAP surface geology, lithological logs, pumping test derived hydraulic properties, water level measurements, water chemistry analyses, and other geophysical measurements. This information will be crucial for informing on aquifer hydrogeological and structural characteristics and will provide data sets useful for scenario modelling using numerical groundwater flow models. Figure 1 displays a simple example that uses only lithological logs for correlation analysis.

Rawlinson, Z.J.; Friedel, M.; Westerhoff, R.; Karaoulis, M.; de Kleine, M. 2014. Mapping hydrogeological properties using helicopter electromagnetic (HEM) data in Otago, 2014 Water Symposium, Blenheim, 24-28th November. Friedel, M.J.; Rawlinson, Z.; Westerhoff, R. 2015. Intelligent mapping of an alluvial aquifer in the Otago region, New Zealand, European Geoscience Union General Assembly 2015, Vienna, 12-17 April.

Figure 1: Cross-sections through the Ettrick Basin showing lithological log data in conjunction with: left) resistivity model from AEM data; right) simple interpretation of resistivity model using correlations of resistivity with lithological logs.

Output 1.4: New Zealand Aquifer Map and Groundwater Atlas (GWR funded)

The current state of knowledge of aquifer boundaries was reviewed by collection of existing aquifer shapefiles from regional authorities. The compiled map highlighted differences in data type (e.g., groundwater management zones vs geological aquifer extent), delineation methods, and the level of information held in each region. The concept of developing a national method for delineation of aquifer boundaries was presented at the GWF meeting in November 2014. This concept was subsequently revised to include development of a National Groundwater Atlas, which was presented to the GWF in May 2015. The delineation of a national aquifer map concept received unanimous support from the forum, and development of a National Groundwater Atlas was also favoured. It is anticipated that this initiative will be followed by a scoping workshop to define delineation methods, atlas content and funding options. Lovett, A.P.; Cameron, S.C. 2015. Development of a National Groundwater Atlas for New Zealand. GNS Science Report SR2014/30. 8 p.

Page 5 of 20

GNS Science

Hydrogeology Department research question 2: What are the fluxes of water into, out of, and through New Zealand's aquifers?

Output 2.1: National estimates of evapotranspiration and rainfall recharge (SAC funded)

A New Zealand wide 1 x 1 km evapotranspiration (ET) dataset, has been produced using satellite derived data. These data have been used to develop a national model of 1 x 1 km monthly rainfall recharge to groundwater, for the period 2000 to 2013. Uncertainty of rainfall recharge estimates has been quantified by error propagation: it uses the sensitivity of the recharge model to each of its input components. The rainfall recharge model results and satellite-derived ET are available for use by national and regional council water resource managers and planners, and researchers. The datasets are especially useful in areas where ground observations are sparse or non-existent. For example, it has been successfully applied in the data-sparse Waipa catchment in a jointly funded GNS Science-Waikato Regional Council aquifer characterisation project.

Westerhoff, R.S.; White, P.; Moore, C. 2015. Rainfall recharge estimation on a nation-wide scale using satellite information in New Zealand, European Geophysical Union General Assembly, Vienna 13- 17 April. Rawlinson, Z.J.; Westerhoff, R.S.; White, P.A; Schaller, K.; Moore C. In review. Estimation of Rainfall Recharge to Groundwater in the Waipa River Catchment from three independent models, GNS Science Consultancy Report 2015/212.

Output 2.2: Rainfall recharge: toward a standard operation procedure for measurements (Waterscape funded)

Following a GNS Science quality assurance and checks of rainfall recharge data from the Canterbury rainfall recharge network, a standard operating procedure for quality assessment of rainfall recharge measurements in lysimeters was suggested by participants at the Lysimeter Workshop, held by NIWA in Christchurch in August 2014. The Canterbury rainfall recharge network data was used to develop a new model of rainfall recharge based on a soil water budget and the sequential Monte Carlo filtering technique to estimate actual evapotranspiration from potential evapotranspiration. A method based on lysimeter measurements to quantify uncertainty in rainfall recharge model estimates was also developed.

Hong, T.; White, P.A. 2015. Rainfall recharge estimation based on a nonlinear Bayesian technique with a dynamic state-space formulation in the Canterbury Plains, GNS Science Report 2014/37. 48 p. White, P.A.; Moreau-Fournier, M.; Thorpe, H.R.; Lovett, A. 2014. Summary of rainfall recharge measurements with lysimeters and ground-level rainfall observations 1952-1978 and 1997-2011, Canterbury, GNS Science Report 2013/10. 31 p. + CD. White, P. 2015. The use of lysimeters to assess the uncertainty of rainfall recharge model estimates, Canterbury, New Zealand, European Geophysical Union General Assembly, Vienna 13-17 April.

Output 2.3: Temperature sensing coupled with radon measurements for model calibration (SAC funded)

Fibre optic distributed temperature sensing (FODTS) equipment was deployed in the Hutt River using radon measurements to inform placement of the cable. The combination of a natural groundwater tracer (radon) and FODTS enabled the groundwater inflow to be quickly and precisely located and quantified, with the results used to improve groundwater flow

Page 6 of 20

GNS Science

model representation of the system. Radon is now another tool, alongside satellite and airborne thermal infra-red imagery, which we can use to inform optimum FODTS placement.

A new, vertical FODTS meter technique, was also successfully used to measure groundwater seepage into Lake Taupo, and validated by traditional seepage meter measurements. This new technique, also applicable in estuaries and wetlands, is quicker and simpler to use than traditional seepage meters. New code and approach was developed to model the flux of groundwater into the lake using the vertical and horizontal FODTS temperature profiling and accounting for the spatial variation in groundwater inflow.

A 1D heat transport model was fitted to FODTS measurements, using spring discharge as the main calibration parameter. This new approach means that spring discharge can be quantified in relatively complex settings. It is a departure from, and an improvement on, existing approaches that generally use a steady state thermal mixing model to infer groundwater discharge. The code can be easily adapted to other hydrological systems.

Martindale, H.; Morgenstern, U.; Toews, M.W.; Singh, R.; Stewart, B. 2014. Mapping Groundwater- Surface Water Interaction Using Radon in the Hutt River, NZ Hydrological & Freshwater Sciences Societies Joint Conference 2014, Blenheim, 24-28 November.

Output 2.4: A new method for baseflow separation (GWR funded)

Understanding and modelling the relationship between rainfall and runoff has been a major focus in hydrology for many years. Baseflow separation and recession analysis have been two of the main tools for understanding runoff generation in catchments, but there are many different methods for each and no consensus on how best to apply each method. A new baseflow separation method has been presented which simulates the baseflow response to rainfall more accurately because it draws from tracer evidence on streamflow. It is now being tested on the many tracer separation studies in the literature, including the Toenepi Stream.

Stewart, M.K. 2015. Promising new baseflow separation and recession analysis methods applied to streamflow at Glendhu Catchment, New Zealand, Hydrology and Earth System Sciences 19:2587- 2603. Stewart, M.K. 2015. Streamflow component separation by tracer and non-tracer methods. IAEA Isotope Hydrology Symposium, Vienna, Austria. 11-15 May. Stewart, M.K. 2015. Separating streamflow components to reveal nutrient flowpaths: Toenepi Stream, Geophysical Research Abstracts 17:EGU2015-7843.

Output 2.5: Tritium application in the Australian ‘Super science’ catchment study (GWR funded)

Understanding the dynamics of the water through catchments has been the main focus of new tritium applications over the last years. This project has now gained significant international traction in Australia, Europe, Japan, and Chile. GNS Science’s high-accuracy tritium technique was applied successfully in the Ovens catchment, an Australian ‘Super science’ water catchment study. This technique enables quantification of groundwater fluxes and lag time for flow and transport model calibration and is very applicable for application in New Zealand.

Cartwright, I.; Morgenstern, U. 2015. Transit times from rainfall to baseflow in headwater catchments estimated using tritium: the Ovens River, Australia, Hydrol. Earth Syst. Sci. 19:3771-3785. Lamontagne, S.; Taylor, A.R.; Batlle-Aguilar, J.; Suckow, A.; Cook, P.G.; Smith, S.D.; Morgenstern, U.; Stewart, M.K. 2015. River infiltration to a subtropical alluvial aquifer inferred using multiple environmental tracers, Water Resour. Res. 51:4532-4549.

Page 7 of 20

GNS Science

Morgenstern, U.; Stewart, M.; Daughney, C.; Townsend, D. 2015. Transit times of baseflow in New Zealand rivers EGU General Assembly 2015 Geophysical Research Abstracts 17:EGU2015-8192. Roig-Planasdemunt, M.; Stewart, M.; Latron, J.; Llorens, P.; Morgenstern, U. 2015. Transit time estimation using tritium and stable isotopes in a Mediterranean mountain catchment, EGU General Assembly 2015 Geophysical Research Abstracts 17:EGU2015-184.

Output 2.6: Parameter estimation to optimise hydrochemical characterisation (co-funded: TVH, Environment Southland)

Self-Organising Maps (SOMs), which are an application of artificial intelligence methods, were used to evaluate relationships among hydrochemical variables. A SOM extension, involving minimization of quality and topological error vectors, enabled estimation of values for hydrochemical parameters that were not actually measured in historical samples. This ability to estimate missing values in the dataset allows a much larger number of samples and analyses to be considered in our established statistical methods like hierarchical cluster analysis (HCA). For example, the SOM and HCA approach applied to the Southland Region allowed us to evaluate data from over 8000 samples as opposed to only 3000 samples when using HCA alone (Figure 2).

Daughney, C.; Rissmann, C.; Friedel, M.; Morgenstern, U.; Hodson, R.; van der Raaij, R.; Rodway, E.; Martindale, H.; Pearson, L.; Townsend, D.; Kees, L.; Moreau, M.; Millar, R. In review. Hydrochemistry of the Southland Region, GNS Science Report 2015/24. Friedel, M.J.; Buscema, M.; Daughney, C.; Litvak, R.; Chambel, A. 2014. Evaluating ground-water quality using artificial adaptive systems, Fall Meeting of the American Geophysical Union 2014, San Francisco, 15-19 December.

Figure 2: Results of HCA for monitoring sites in Southland, based on measured or SOM-estimated values of 13 commonly analysed parameters. Clusters 1A0, 1B0, 1C1 and 1C2 are generally indicative of oxic, pristine hydrochemistry; clusters 2A1, 2A2, 2B0 and 2C0 are generally indicative of oxic, anthropogenically impacted hydrochemistry; and clusters 3A0, 3B1 and 3B2 are generally indicative of anoxic hydrochemistry. Surface water sites are identified by small black dots in the centre of the symbols.

Page 8 of 20

GNS Science

Output 2.7: The role of bedrock groundwater in headwater catchments, Maimai (GWR, University of Saskatchewan)

The Maimai catchment studies in the South Island, starting in the late 1970s, are some of the most advanced catchment studies in the world in regards to understanding hill slope hydrology including subsurface flow. Thirty new wells have been drilled over the recent months for understanding bedrock groundwater contributions to streamflow. GNS Science is involved in a new PhD project in the Maimai catchment: “The role of bedrock groundwater in headwater catchments: Processes, patterns, storage and transit time”. This information on how catchments store and release the water, and the lag time of associated contaminants, are important pieces of information for the sustainable management of water resources.

Output 2.8: A new SMART method to sample shallow groundwaters – Push Drill (GWR funded)

A push drill has been trialled successfully onshore for collecting groundwater samples from depth profiles. In the ignimbrite near the shore of Lake Taupo, a depth of 23 m was reached within a few hours. This equipment allows the quick and cost effective collection of samples along groundwater flow paths, for example for measurement of recharge or denitrification rates.

McBeth, K.; Morgenstern, U.; Lovett, A. 2014. Direct push sampling of groundwater in New Zealand, NZ Hydrological & Freshwater Sciences Societies Joint Conference 2014, Blenheim, 24-28 November.

Output 2.9: New software to investigate the effect of regional groundwater flow on temperature distribution in a geothermal reservoir (GNS Science contestable MBIE Geothermal Supermodels programme)

To understand the effect of regional groundwater flow on the temperature distribution in a geothermal reservoir requires modelling of self-potential in response to coupled flows induced by primary potentials associated with flow of water, heat and resistivity. New software was developed to conduct explicitly-coupled forward and inverse modelling of hydrogeological and geophysical field data (self-potential). Application of this software showed that it is possible to model the spontaneous potential using temperature observations from the Monroe-Red Hill (Utah, USA) geothermal system. Joint inverse estimation and distribution of thermal conductivity, coupling coefficients, and electrical resistivity was possible using Tikhonov regularization. On-going work is the implementation of a cross-gradient constraint to simultaneously estimate hydrogeophysical properties at the hydrothermal deposit. The case study areas include the Wairakei-Tauhara geothermal field (New Zealand), and Monroe-Red Hill geothermal area.

Page 9 of 20

GNS Science

Hydrogeology Department research question 3: What are the fluxes of key substances into, out of, and through New Zealand's aquifers?

Output 3.1: Baseline trends (GWR funded)

To define the chemical status of a groundwater body, both the naturally occurring range of chemical concentrations and the range of chemical rate of changes are required. Preliminary analysis was undertaken to establish baseline trends for New Zealand groundwaters using an amalgamated dataset (NGMP and aggregated State of the Environment programmes). Results highlighted temporal changes in trends at some sites between consecutive 5-year time windows. This method also allowed us to identify sites at which groundwater quality shows signs of land use impact, which means that these could be removed from baseline determination. A further study is to be conducted using the updated dataset collected as part of this year’s national reporting.

Moreau, M.; Daughney, C.J. 2014. Setting national baselines for trends in groundwater quality using multivariate statistical methods, International Association of Hydrogeologists IAH, the Moroccan Chapter - 41st IAH International Congress "Groundwater : Challenges and Strategies" - Marrakech, September, 15-19, 2014.

Output 3.2: Understanding the relationship between groundwater phosphorus concentrations and land use (GWR funded)

Working with colleagues from AgResearch, we investigated the relationships between phosphorus concentration in groundwater and the overlying land use. This study showed that phosphorus (P) concentrations were enriched in groundwaters below dairying land use, particularly for gravel or sand aquifers. This relationship was not affected by the redox status of the groundwater and applied equally to oxic and anoxic groundwaters. This study also identified a relationship between P concentrations in surface water and groundwater, suggesting that P may be transferred between surface waters and aquifers in some locations.

McDowell, R.; Cox, N.; Daughney, C.J.; Wheeler, D.; Moreau, M. 2014. A national assessment of the potential linkage between soil, and surface and groundwater concentrations of phosphorus, NZ Hydrological & Freshwater Sciences Societies Joint Conference 2014, Blenheim, 24-28 November.

Output 3.3: Novel age tracers: radon and halon (SAC and GWR funded)

The radon technique to identify locations of groundwater discharge in surface water continues to prove useful in New Zealand, with studies undertaken in the Hutt and Mangatainoka rivers, as well as surface water bodies in Southland, Hawke’s Bay, Waikato and Marlborough. Radon measurements were combined with other techniques, such as FODTS, to provide groundwater flux information in the Hutt River.

It was previously reported that a new age tracer, halon-1301, was developed as a suitable replacement for chlorofluorocarbons, which has contamination issues. The use of halon-1301 is extremely efficient as it can be analysed simultaneously with SF6 from the same sample. This causes only little additional cost for the benefit gained of taking a third age tracer for the establishment of groundwater dynamics and validation of groundwater flow models. The behaviour of halon-1301 as a groundwater age tracer in aquifers of the Greater Wellington Region has now been established. Waikato Regional Council has now added tracers into routine monitoring this year.

Page 10 of 20

GNS Science

Beyer, M.; van der Raaij, R.; Morgenstern, U.; Jackson, B. 2015. Assessment of Halon-1301 as a groundwater age tracer, Hydrol. Earth Syst. Sci. 19:2775-2789, doi:10.5194/hess-19-2775-2015. Morgenstern, U.; Townsend, D.; Davidson, P.; Martindale, H. 2014. Rai-Pelorus Groundwater Baseline Study - Residence Time, Recharge Source, Rate and Volume, Resurgence into Rivers, and Impact of High Intensity Land Use Activities on Groundwater Quality, GNS Science Report 2014/31. 51 p.

Output 3.4: NGMP data (GWR funded)

The NGMP network presently consists of 110 active sites across New Zealand (Figure 3). Four new sites have been added to the NGMP network in the Taranaki region, and additional sites are being reviewed for the Wanganui-Manawatu and Wellington regions. Following discussion with Tasman District Council, it was decided to increase the monitoring frequency of dissolved reactive phosphorus species from annually to quarterly for spring sites. This is because, at these sites, algal growth is an environmental concern. Correspondence between the NGMP site identification number and site names, detailed account of sampling history (July 2014 to June 2015), and age tracer analyses and the most up-to-date age interpretations are enclosed in an attachment to this letter (NGMP data summary 2014_2015.xls).

Attachment: NGMP data summary 2014_2015.xls

Figure 3: NGMP network site location.

Page 11 of 20

GNS Science

Output 3.5: Isotope methods for tracking the sources and fate of dissolved inorganic nitrogen (collaborative funding)

Seven years of projects and collaborations have developed tools using natural abundance isotopes techniques to track dissolved nitrogen (N) from its source to receiving environment. By studying N isotopes widely in soils, and specifically in dairy cow urine patches, we have clarified why nitrate from pastoral soil sources typically has a relatively stable N isotope ratio 15 15 15 (δ N) resembling bulk soil δ N. Across sources, the dual isotope tracers δ N-NO3 and 18 δ O-NO3 show that most surface-water nitrate derived from pastoral sources clusters tightly, but shows variation related to the catchment-wide intensity and duration of pastoral agriculture. The stability of these typical sources can allow the differentiation of other sources, such as effluents and some types of fertilisers. Where the source signature can be 15 18 confirmed, δ N-NO3 and δ O-NO3 also has great utility for quantifying attenuation due to denitrification and other processes. Combined with direct measurements of the δ15N value of

NH4 our methods enable the isotope tracing of N from soil sources into freshwater food webs. When combined with high throughput analyses of δ2H and δ18O in precipitation, soil and streamwater, as well as other water dating tracers, it is becoming realistic to affordably track N impacts in freshwater back to a source or sources.

Wells, N.S.; Baisden, W.T.; Clough, T.J. 2015. Ammonia volatilisation is not the dominant factor in determining the soil nitrate isotopic composition of pasture systems. Agriculture, Ecosystems & Environment 199: 290-300, http://doi.org/210.1016/j.agee.2014.1010.1001. Wells, N.S.; Baisden, W.T.; Horton, T.; Clough, T.J. In Review. Spatial and temporal variations in nitrogen export from a New Zealand pastoral catchment revealed by streamwater nitrate isotopic composition. Water Resources Research.

Output 3.6: Production scenarios under climate change (Climate Change Impacts and Implications Programme)

We have adapted the Biome-BGC (BioGeochemical Cycles) and Land Use in Rural New Zealand models to simulate pastoral agriculture and to make land-use change, intensification of agricultural activity and climate and land-use change scenario projections of New Zealand's pasture production. Results show up to a 10% increase in New Zealand's national pasture production by 2020 under intensification and a 1-2% increase by 2050 from economic factors driving land-use change. Climate change scenarios using statistically downscaled global climate models from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report also show national increases of 1-2% by 2050, with significant regional variations. Projected out to 2100, however, these scenarios are more sensitive to the type of pasture system and the severity of warming: dairy systems show an increase in production of 4% under mild change but a decline of 1% under a more extreme case, whereas sheep/beef production declines in both cases by 3 and 13%, respectively. We are currently working with the Climate Change Impacts and Implications Programme (NIWA/Landcare Research) to compile pasture and forest production and water budgets for newly downscaled IPCC 5th Assessment Report scenarios, nationally and in regional case studies.

Keller, E.D.; Baisden, W.T.; Timar, L.; Mullan, B.; Clark, A. 2014. Grassland production under global change scenarios for New Zealand pastoral agriculture. Geoscientific Model Development 7(5): 2359-2391.

Page 12 of 20

GNS Science

Hydrogeology Department research question 4: How have/will human activities, climate change and other pressures affect New Zealand's groundwater resources?

Output 4.1: Loose groundwater-surface water coupling of a regional scale flow model (co-funded: TVH, Environment Southland, NIWA)

A regional-scale groundwater flow model is currently being developed for Southland. This will be an extension of the modelling work that has been previously undertaken in the TVH programme for the Wairarapa and Lake Rotorua catchments. Importantly, the Southland regional model will cover an area roughly four times larger than the Wairarapa. A set of GIS protocols have been developed to represent the river network within the Southland groundwater model in a way that will allow for coupling with NIWA's TopNet and Clues surface water models. The Southland project has the specific intent of facilitating this model coupling to assist regional councils with water quality limit setting under the recent National Policy Statement for Freshwater Management. The development of the regional groundwater model for Southland will be informed by dating of the baseflow in the main rivers. The age of stream water at baseflow quantifies the residence time of groundwater at the catchment- scale. This is a novel application of water dating that is gaining traction across other regions of New Zealand and internationally.

Morgenstern, U.; Stewart, M.K.; Daughney, C.J.; Begg, J.; Townsend, D.; Martindale, H.; Matthews, A.; Roygard, J.; Clark, M.; Rissmann, C.; Chanut, P.; Hodson, R.; Davidson, P.; Hadfield, J.; Vant, B.; McDonnell, J. 2014. Transit times of baseflow in New Zealand rivers, General Assembly of the European Geophysical Union, Vienna, Austria, April 2015. Daughney, C.; Rissmann, C; Friedel, M.; Morgenstern, U.; Hodson, R.; van der Raaij; R; Rodway, E.; Martindale, H.; Pearson, L.; Townsend, D.; Kees, L.; Moreau, M.; Millar, R.; Horton, T. In review. Hydrochemistry of the Southland Region, GNS Science Report 2015/24.

Output 4.2: The use of groundwater age and hydrochemistry to understand source and fate of nutrients, Lake Rotorua (GWR and TVH funded)

The water quality of Lake Rotorua has steadily declined over the past 50 years despite mitigation efforts over recent decades. Due to delayed response of the groundwater discharges to historic land-use intensification 50 years ago, a unique set of high-quality tritium data, collected over more than four decades, was used for detailed understanding of the origin, fate, flow pathways, lag times and future loads of contaminants of the water discharging into Lake Rotorua. HCA of the water chemistry parameters provided evidence of the recharge source of the large springs near the lake shore. Groundwater chemistry and age data show clearly the source of nutrients that cause lake eutrophication: nitrate from agricultural activities and phosphate from geologic sources. With a naturally high phosphate load reaching the lake continuously via all streams, the only effective way to limit algae blooms and improve lake water quality in such environments is by limiting the nitrate load.

Morgenstern, U.; Daughney, C.J.; Leonard, G.; Gordon, D.; Donath, F.M.; Reeves, R. 2015. Using groundwater age and hydrochemistry to understand sources and dynamics of nutrient contamination through the catchment into Lake Rotorua, New Zealand, Hydrol. Earth Syst. Sci. 19:803-822.

Output 4.3: Climate signals in New Zealand groundwater (GWR funded)

Mean annual temperatures in New Zealand during the Last Glacial Maximum have been derived from dissolved noble gases in groundwater. We have shown that climate signals are archived in, and can be recovered from, groundwater in New Zealand. The research aims to

Page 13 of 20

GNS Science

resolve the controversy between paleo-oceanographic and glacial-snow line based records and is an excellent example of the contribution of groundwater research to understanding of climate change.

Seltzer, M.; Stute. M.; Morgenstern. U.; Stewart, M.K.; Schaefer J.M. Accepted. Mean annual temperature in New Zealand during the Last Glacial Maximum derived from dissolved noble gases in groundwater, EPSL.

Output 4.4: Climate signals from ice cores (International collaboration funds)

Ice sheets play a fundamental role as archives for global climate change. They contain a variety of proxies for climate forcing, such as the greenhouse gases CO2 and CH4, dust, aerosols and solar irradiance, as well as corresponding climate responses such as precipitation rate, temperature and wind strength. Accurate dating of ice cores is crucial to make full use of this information. Tritium and 32-Silicon stored in the ice provide a precise natural clock for this purpose. Our continued research in this area deepens our understanding of the earth’s climate, which underpins New Zealand climate models.

Kang, S.; Wang, F.; Morgenstern, U.; Zhang, Y.; Grigholm, B.; Kaspari, S.; Schwikowski, M.; Ren, J.; Yao, T.; Qin, D.; Mayewski, P. A. 2015. Dramatic loss of glacier accumulation area on the Tibetan Plateau revealed by ice core tritium and mercury records, The Cryosphere 9:1213-1222. Grigholm, B.; Mayewski, P.A.; Kang, S.; Zhang, Y.; Morgenstern, U.; Schwikowski, M.; Kaspari, S.; Aizen, V.; Aizen, E.; Takeuchi, N.; Maasch, K.A.; Birkel, S.; Handley, M.; Sneed, S. 2015. Twentieth century dust lows and the weakening of the westerly winds over the Tibetan Plateau, Geophys. Res. Lett. 42: 2434-2441. Jenk, T.; Graesslin-Ciric, A.; Tobler, L.; Gäggeler, H.; Morgenstern, U.; Casassa, G.; Lüthi, M.; Schmitt, J.; Eichler, A.; Schwikowski, M. 2015. The Mercedario ice core – an excellent archive for ENSO reconstruction, EGU General Assembly 2015 Geophysical Research Abstracts 17:EGU2015-9374.

Output 4.5: The Geothermal and Groundwater database activities (GWR funded)

The Geothermal and Groundwater database has a new compact interface, with simplified navigation and added data browsing features. The “Map” page enables users to turn on and off dataset and metadata, such as geothermal fields and aquifers. The “Home” page allows to view and browse directly features, using pre-defined filters (project, region, geothermal field). Public use has been facilitated by removing the automated sign-up email (acceptance to the terms and conditions are still required). Two manuals dedicated respectively to the public and the registered user, are currently under review.

A new public dataset, Hydrochemistry of the Lake Rotorua Catchment, was added to the database. It contains groundwater and surface water hydrochemical data collected in the Lake Rotorua catchment. This dataset consists of 152 sites, 147 samples and 2,690 individual results, and adds to the four existing public datasets held in the database (NGMP, Air Particulate Matter, Volcano monitoring and the Bay of Plenty Regional Council Geothermal Surface Feature Database).

The public NGMP dataset is up-to-date, with a total of 9,876 samples and 147,796 individual results (497 samples and 9,948 results uploaded this year). The restricted-access State of the Environment dataset was updated to include 181,165 individual results for selected parameters. The entire dataset currently contains 68,365 samples and 708,695 individual results. All regional dataset extend to 2014. For more information, or to enquire about updating the regional datasets in the database, contact: [email protected]. Link to the Geothermal and GroundWater database.

Page 14 of 20

GNS Science

Output 4.6: Groundwater data portal development update (SAC funded)

GNS Science has continued to be a strong contributor at workshops on developing National Environmental Monitoring Standards (NEMS) for data transfer in New Zealand, specifically the Environmental Observation Data Profile (EODP). The EODP, currently in draft form, provides clear guidance to implement and use compliant web services. The future release of the NEMS OEDP standards will provide a dramatic increase in the ease of transfer of time series and environmental observation data across many sectors of New Zealand (e.g., environmental research, engineering research). Link to the SMART Groundwater Portal.

Ritchie, A.; Schmidt, J.; Hodges, S.; Watson, B.; Kmoch, A.; White P.A. 2014. Development of a New Zealand hydrology time series data exchange standard, NZ Hydrological & Freshwater Sciences Societies Joint Conference 2014, Blenheim, 24-28 November.

Output 4.7: Web-based data portal for the Awahou catchment under development (NRW funded)

The Awahou Portal (Figure 4) developed as part of the “Ka Tu Te Taniwha – Ka Ora Te Tangata” project and utilising the SAC data portal technology, will enable restricted access to land use history, Mâtauranga-a-iwi, and scientific information. Ngati Rangiwewehi believes the Awahou Portal will improve understanding and management of the freshwater resource and preserve knowledge for future generations. Link to the NRW project.

Kmoch, A.; Cameron, S.; Mohi, G.; Lovett, A.; Rawlinson, Z.; Bradshaw, D.; Klug, H.; White, P. 2015. Spanning worlds: A SMART data portal for traditional knowledge of freshwater resources, Te Kahui Manu Hokai – Maori GIS Association: PLACE 2015, 10-12 June. Rawlinson, Z.J.; Hancock, R.; Kmoch, A.; Cameron, S.; Klug, H.; Lovett, A.; Mohi, G.; White, P. 2015. Wai Maori, Whenua Ora – Water quality and allocation in our environment, TAP 2015 Te Ara Putaiao, Rotorua, 22-23 June.

Figure 4: Visualisation of the Awahou portal.

Page 15 of 20

GNS Science

Output 4.8: Downloadable groundwater tools usage, GNS Science website (GWR funded)

GNS Science has been developing free tools to support groundwater research (Table 3):

• An excel-based spreadsheet for calculating water quality descriptive statistics and perform trend analysis. Link to the gns.calculator. • A excel-based visualisation tool to assess the relative size of capture zone delineation using the simple methods (calculated fixed radius, uniform flow equation). Link to the gns.simple-methods. • A GIS-based capture zone delineation toolkit to automatically delineate well capture zone using either the calculated fixed radius or the uniform flow equation methods. This tool is available either ready to use (ArcGIS toolbox) or as the source code (Python). Link to the gns.capture-zone-toolkit.

Table 3: Usage summary for each GNS Science groundwater tools.

Tool License Public release #downloads #runs restriction year (Jul14-Oct15) (Jul14-Oct15)

Non- Version 0.0:2012 4,195 gns.calculator 312 commercial use Version 8.0: 2015 (51% in New Zealand)

gns.capture-zone-toolkit None 2014 36 N/A

gns.simple-methods None 2014 44 57

Output 4.9: “Earth Beneath Our Feet” website (GWR funded)

A smartphone app has been developed which allows location-aware access to 3D geological model data via the “Earth Beneath Our Feet’ web-platform. The app uses the GPS or network locations of the smartphone to identify what the geology is directly at your location. This app is currently available for several Bay of Plenty sub-regions. Further regions will be included in the future. Link to the Earth Beneath Our Feet website

Tschritter, C.; White, P.; Moreau, M.; White, D. 2014. Mobile apps for hydrogeological and geological data collection, access and visualisation, NZ Hydrological & Freshwater Sciences Societies Joint Conference 2014, Blenheim, 24-28 November.

Page 16 of 20

GNS Science

Other GNS Science hydrogeology-related research projects

Earthquake Hydrology: Seismic Pumps or Broken Pipes (Marsden funded)

In the first systematic investigation of earthquake hydrology in New Zealand, this project is examining and modelling rich datasets of water level-, aquifer- and flow-changes induced by shaking, stress and strain. The project aims to elucidate spatial distributions of dynamic stress (‘seismic pump’) vs static stress (‘broken pipe’) causal mechanisms, to deliver internationally important examples of crustal hydromechanics from New Zealand, relevant locally for understanding liquefaction, informed engineering, and security of water supply. Changes in groundwater levels that occurred across New Zealand during the recent South Island earthquakes have now been compiled, quantified, and classified according to different aquifers, local hydrogeology and borehole depth. Changes to aquifer flow properties have been observed from pump-testing of wells in the field. Shaking (as measured by seismometers) and stress changes in the ground are being systematically quantified for each major earthquake so they can be related to well sites where hydrological responses have been observed. Provisional analysis suggests confined aquifers experienced comparatively large earthquake-induced pressure changes, and shaking at different frequencies, than places where groundwater is unconfined.

Cox, S.C.; Rutter, H.K.; Sims, A.; Manga, M.; Weir, J.J.; Ezzy, T.; White, P.A.; Horton, T.W.; Scott, D. 2012. Hydrological effects of the Mw 7.1 Darfield (Canterbury) earthquake, 4 September 2010, New Zealand. New Zealand Journal of Geology and Geophysics, 55(3): 231-247. Cox, S.C.; Menzies, C.D.; Sutherland, R.; Denys, P.H.; Chamberlain, C.; Teagle, D.A.H. 2015. Changes in hot spring temperature and hydrogeology of the Alpine Fault hanging wall, New Zealand, induced by distal South Island earthquakes. Geofluids (15): 216-239. DOI: 10.1111/gfl.12093.

Did artesian groundwater contribute to Christchurch liquefaction and lateral spreading damage? (Natural Hazards Research Platform funded)

Present geotechnical best-practice assessment of liquefaction hazards is focussed on the triggering of the process by which an earthquake causes poorly consolidated, groundwater- saturated, geological materials to temporarily lose strength and stiffness and permanently volumetrically consolidate.

Assessments typically only consider the shallow water table position. While liquefied ground presents an engineering challenge, the repeated invasion of properties by ejecta and the resulting differential ground surface subsidence adds a heavy societal cost to this hazard. Results from this project indicate that where confined groundwater pressure is artesian (above ground) there are higher probabilities of liquefaction, with pressure escape providing an additional driving mechanism for the ejection of liquefied material to the surface. Hazard assessments consequently also need to consider the wider hydrogeologic environment.

The severity of the observed liquefaction damage in Christchurch, is linked to the fact that the city is built over aquifers with substantial artesian groundwater pressure, and may be an extreme example that may not be widely applicable elsewhere. Key results are presently in manuscripts under review (October 2015). van Ballegooy, S.; Cox, S.C.; Agnihotri, R.; Reynolds, T.; Thurlow, C.; Rutter, H.K.; Scott, D.M.; Begg, J.G.; McCahon, I. 2013. Median water table elevation in Christchurch and surrounding area after the 4 September 2010 Darfield Earthquake. : GNS Science. GNS Science Report 2013/01. 66 p. + 8 appendices.

Page 17 of 20

GNS Science

van Ballegooy, S.; Cox, S.C.; Thurlow, C.; Rutter, H.K.; Reynolds, T.; Harrington, G.; Fraser, J.; Smith, T. 2014. Median water table elevation in Christchurch and surrounding area after the 4 September 2010 Darfield Earthquake: Version 2. GNS Science Report 2014/18, 79 pages + 8 appendices. Ward, N.F.D (2015 in press). On the mechanism of earthquake induced groundwater flow. Journal of Hydrology.

Hutt River toxic Algae blooms (co-funded: GNS Science, VUW postgraduate Environmental Sciences Course and Greater Wellington Regional Council)

Nuisance toxic algae blooms in the Hutt River have affected the water quality each summer for the last decade. They occur in summer at low river flow levels, and expected to be caused by excess nutrients entering the river. A range water samples from the Hutt and Mangaroa River's have been sampled to investigate nitrate levels and their origin. The use of bio-indicators has also been investigated with a pilot study to investigate the stable isotope values of algae and primary producers to understand the transfer of nutrients from the water through the food web. The Hutt River toxic algae work is a joint initiative with GNS Science, VUW postgraduate Environmental Sciences Course and Greater Wellington Regional Council.

Pacific Island drinking water security (University of Reunion and GNS Science funded)

A range of isotope and chemical baseline measurements have been made over three years to characterise the quality and security of Lifou Island's (Loyalty Islands) drinking water. Monthly rainfall and tap water were measured to determine the effects of precipitation on aquifer recharge, and assess drinking water for nitrate contamination. Wet and dry seasonal changes were also monitored directly from irrigation and drinking water boreholes and local fresh water springs to understand the stability and recharge mechanism of the freshwater lense. The karstic nature of the aquifer lends a high risk and vulnerability to the security of drinking water, and this study is significant that it provides a baseline for future monitoring. The study was funded by University of Reunion and GNS Science.

Nicolini, E.; Rogers, K.M.; Rakowski, D. 2015. Baseline geochemical characterisation of a vulnerable tropical karstic aquifer; Lifou, New Caledonia. Journal of Hydrology. (Published), 10.1016/j.ejrh.2015.11.014.

Page 18 of 20

GNS Science

We hope you will find this information useful. Please do not hesitate to contact us if you would like to give us feedback or comments.

Yours sincerely

Magali Moreau Conny Tschritter Stewart Cameron Groundwater Geochemist Hydrogeologist Head of Department Hydrogeology

On behalf of contributing authors: Abigail Lovett Alexander Kmoch Catherine Moore Chris Daughney Karyne Rogers Liz Keller Maryam Moridnejad Mike Friedel Mike Toews Paul White Rob van der Raaij Rogier Westerhoff Simon Cox Troy Baisden Uwe Morgenstern Zara Rawlinson

Attachment: NGMP data summary 2014_2015.xls

Page 19 of 20

GNS Science

Appendix 1: Glossary of acronyms

AEM Airborne ElectroMagnetic

EODP Environmental Observation Data Profile

ET Evapotranspiration

FODTS Fibre optic distributed temperature sensing

GWF Groundwater Forum

GWR Groundwater Resources of New Zealand

HCA Hierarchical Cluster Analysis

IPCC Intergovernmental Panel on Climate Change

MBIE Ministry of Business Innovation and Employment

N Nitrogen

NEMS National Environmental Monitoring Standards

NIWA National Institute of Water and Atmospheric Research

NGMP National Groundwater Monitoring Programme

NRW Ka Tu Te Taniwha – Ka Ora Te Tangata research programme

QMAP 1:250 000 Geological Map of New Zealand

SAC Smart Aquifer Characterisation research programme

SOM Self-Organising Map

TVH Tracer Validation of Hydrological Systems research programme

Page 20 of 20

GNS Science