Water New Zealand Christchurch Regional Meeting

More than 40 freshwater related topics are being researched at the University of Canterbury, in departments ranging from Hydrological engineering to Law. The College of Engineering and the Waterways Centre for Freshwater Management are selecting a number of postgraduate students to present on some of these topics at the next Christchurch Regional Meeting. Presentations will include research looking at the complex interface between freshwater and the environment, 3 waters systems, and surface/groundwater interactions.

There will be 5 presentations followed by networking and the opportunity to view students poster presentations. Details and speaker bios will be available shortly.

Draft Agenda:

3.00 - 3.05: Water New Zealand Welcome

3.05 - 3.30: Michaela Aspell, Tonkin Taylor, YWP Conference Award Winner 2016 - Lyttelton Port Company Channel Deepening

Lyttelton Port Company (LPC) is proposing a channel deepening project to lengthen, widen and deepen the existing navigation channel in Lyttelton Harbour. This will be the largest dredging project ever undertaken in New Zealand and allow the Port to keep up with the international trend of increasingly larger container vessels.

As part of the consenting approach, LPC undertook a comprehensive assessment of environmental, cultural, recreational and economic effects. Assessments were based on hydrodynamic modelling of the dredge-associated sediment plumes and morphological modelling of disposed sediment.

LPC is proposing a water quality monitoring system which involves 15 real-time monitoring stations collecting data on water quality and meteorological conditions throughout Lyttelton Harbour and offshore Banks Peninsula. Real-time turbidity readings will be compared to trigger levels to guide dredge operations and ensure minimal effects from dredge-related sediment plumes. Developed with key stakeholders, including manawhenua and aquaculture industry, the water quality monitoring system will be unlike any other ever used in a coastal environment in New Zealand, providing both Port and public real-time water quality and meteorological information.

3.30 - 3.35: Introduction from UC academic

3.35 - 4.00: Katie Coluccio (Waterways Masters student) “Comparison of methods for measuring groundwater-surface water interactions in braided rivers”

Braided rivers are often highly connected to groundwater systems, with water flowing between the two systems. Rivers can gain surface flow from groundwater and likewise lose flow to subsurface groundwater systems. It is important to understand the interactions between groundwater and surface water systems so that water use can be sustainably allocated and to improve knowledge of contaminant transport. Braided rivers present several challenges for measuring groundwater-surface water exchange including their coarse gravel beds, flashy flood flows, heterogeneous make-up of streambeds and meandering channels. This study will assess the usefulness of a number of field methods for characterising groundwater-surface water interactions in the South Branch of the Ashburton River in Canterbury. This study will involve the installation of mini-piezometers and vertical temperature probes into the riverbed and margins to highlight areas of groundwater-surface water exchange. Results will be compared to flow gauging carried out in the river. Water samples will also be collected to compare in-stream and groundwater chemistry to improve the understanding of water and nutrient sources for the Ashburton River.

4.00 - 4.25: Will Dench (Waterways Masters student) “ Changes in the Mayfield Hynds aquifer following a shift from border dyke to to spray irrigation"

The Hinds Rangitata Plain (HRP) is located on the Canterbury Plains and bound by the Rangitata and Hinds Rivers, Southern Alps foothills and the Pacific Ocean. Irrigated agriculture on the HRP started in 1947 with the completion of the Mayfield Hinds Irrigation Scheme (MHIS). The Rangitata River supplies freshwater to the MHIS from the Rangitata Diversion Race (RDR). The MHIS operates today as a farmer owned co-operative, delivering water to more than 33,000 hectares of highly productive land.

Irrigation practices on the HRP have changed in the past decade from primarily border dyke irrigation to spray irrigation. Border dyke irrigation, a type of flood irrigation method, provides greater quantities than what the soil can hold and results in large amounts of irrigation water recharging the underlying groundwater. Spray irrigation applies water at a uniform rate and results in a reduced loss of irrigation water to groundwater, compared to border-dyke irrigation. The reduced groundwater recharge associated with conversion to spray-type irrigation is thought to have considerable impacts on HRP groundwater resources. These impacts include declining groundwater levels, drying of shallow wells and a reduction of baseline flow in coastal spring-fed waterways.

Continuous declines in groundwater quantity and quality over the past decade in the HRP pose a serious risk to drinking water sources and waterways ecology. The aim of the current project is to improve understanding of the change in groundwater hydrology in the HRP following conversion from border dyke to spray irrigation.

4.25: - 4.50: Fabio Silveira (UC CNRE) “Dynamics of nitrogen compounds at Haytons Stream, Christchurch”

Previous studies have shown levels of ammoniacal nitrogen (NH 4-N) and oxidized nitrogen (NO X-N) in Haytons Stream was one of the highest among Christchurch City waterways. There was thus a need to understand the dynamics of nitrogen compounds in Haytons Stream.

Nitrogen compounds were characterized as NH 4-N, NO X-N, dissolved organic nitrogen (DON) and particulate organic nitrogen (PON) through spatial and temporal field sampling along Haytons Stream.

Most of nitrogen was found to be in its dissolved form (NH 4-N, NO X-N and DON), mainly in its inorganic form (NH 4-N and NO X-N) under baseflow conditions and in its organic form (PON and DON) under stormflow conditions.

Overall, nitrogen concentrations increased from the upper part to the middle part and decreased downstream. Point discharges of NH 4-N and DON occurred at the upper and middle part of the stream with NH 4-N reaching toxic levels mainly in the upper-middle part of the stream.

It can be concluded that stormwater management along the stream should be focused on the dissolved forms of nitrogen. The wetland/ponds at the outlet of Haytons Stream does a good job of converting nitrogen to a predominantly PON (i.e. algae), which could be removed through filtering or other physical treatment means to mitigate PON entering Heathcote/Opawaho River.

4.50 - 5.15: Robert Prileszky (UC CNRE) ”Modelling the Organisational Health and Resilience of Infrastructure Service Providers”

Infrastructure organisations provide an essential service for modern society and are especially vital for assisting recovery after significant events such as major earthquakes. The resilience of the organisation and how it copes with disruption is fundamental to successful service provision.

Organisations and their operation can be viewed as complex systems comprising the interacting behaviours of physical, human and organisational elements. These elements - and their effects on each-other - determine the performance of the system as a whole. Organisations can fail under stress, and gaining greater knowledge of the behaviour of infrastructure organisations before, during and after a disruptive event is the driver for this project.

The project - sponsored by the Earthquake Commission - aims to develop dynamic models to describe the organisational health and resilience of infrastructure service providers. Simulated scenarios will enable the identification of success and failure paths of the organisation under stressed conditions, and also identify leverage points for improvement and possible lead-indicators of failure. The models will be validated though consultation with the infrastructure service providers, and historical data from Resilient Organisations’ benchmarking research will be used as initial parameters.

This research is novel in that it will incorporate physical, organisational and human aspects as contributing factors to dynamic organisational performance. It will provide valuable insight to a complex issue.

5.15 - Networking

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