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Tree Canopy Cover in Kerikeri 2015
No full textThis report was prepared by Professor Justin Morgenroth and Dr. Ning Ye at the School of
Forestry, University of Canterbury. The aim of this report is to provide local authorities in New
Zealand with a basic understanding of the urban tree canopy cover within their cities and towns
Beyond vegetation abundance: urban green equity through the lens of an NDVI-based approach.
No full textThe interplay of urbanisation and climate change presents global challenges that demand implementation of innovative, localised adaptation responses. Vegetation is any form of green biomass, i.e. trees, shrubs, and other low laying plants. Increasing the amount, or abundance of vegetation is one way to mitigate these challenges. A gap remains within the scope of spatial assessments between physical, natural, and semi-natural land environments of urbanscapes and urban green equity in localised contexts across Aotearoa-New Zealand. This research aims to understand how abundant vegetation can be retrofitted effectively into environmentally deficient urban areas to increase ecological and environmental sustainability, equity, and community health and wellbeing within the urban area of Rangiora, Canterbury. Data involved an 8-band Planet Scope satellite imagery and cross-sections of vector data on residential zoning, building outlines and a 250m estimated population grid. Analysed in three phases, the normalised difference vegetation index (NDVI) assessed vegetation abundance. 300-meter buffer zones substituted for 10-minute walkable distances to abundant vegetation, from these NDVI values and measured against residential-zoned buildings and the estimated population grid. A qualitative photo-embedded analysis supported the qualitative analyses, depicting information on vegetation abundance from a ground-level view. The findings showed the area to have abundant vegetation overall. Areas most deprived of vegetation were parts of the residential zone, the industrial areas, and the urban centre. This research provided The Waimakariri District Council with recommendations towards retrofitting abundant vegetation in sections of the Rangiora urban area devoid of vegetation and can aid the decision-making process in the Waimakariri District. This research underscores how incorporating innovative nature-based solutions into urban planning and design can create more sustainable, equitable, and liveable, resilient urban ecosystems
Impact of MVDC Cables on the Energy Transition
No full textElectricity plays an important role in enabling the energy transition to reduce greenhouse gas emissions
to net-zero by 2050. Having DC subsystems at all voltage levels will enable more efficient transmission
of electricity, reduce the number of converters and hence losses, and result in a more reliable system.
MVDC cables will be a key technology for the future. The refurbishing of existing MVAC cables resp.
the application of new MVAC XLPE cables for DC operation is very promising. The basic idea is to
allow a mean electric field of 10 kV/mm for MVDC cables, which today’s MVAC cables can fulfil. In
this context, it is a clear benefit that today’s MVAC cable systems are accompanied by a stable supply
chain and well-standardised quality assurance methods.
Intensive research was done to understand the DC phenomena of extruded MVAC cables. The investigations described here deal with the increase in transmission capacity, the conductivity and space charge
accumulation thresholds of MVAC XLPE, electrical treeing under DC, breakdown strength under TOV
stress and optimized type test and PQ test procedures.
The aforementioned work has shown that reliable MVDC cable systems are available against this
background
Tree Canopy Cover in Rolleston 2023
No full textThe aim of this report is to provide local authorities in New Zealand with a basic understanding of the urban tree canopy cover within their cities and towns
Using facial recognition to detect operator stress.
No full textContext: Operator emotional states and physiological responses critically influence safety,
cognitive load, and performance during milling operations. Understanding how cutting
parameters and environmental stressors affect these responses is essential for developing
emotion aware manufacturing systems. Objectives: This study quantifies operator physiological
responses and emotional transitions under varied machining conditions and models relationships
among emotions, vibration, sound, and heart rate. Methods: Two participants completed 27
milling tasks with varying cutting speeds (500 –1100 rpm), axial depths (0.1 – 0.5 mm), and feed
rates (125 –275 mm/min). Facial emotion recognition captured frame by frame affect (Happy,
Sad, Fear, Surprise), while heart rate, vibration, and sound were recorded synchronously.
Emotional transitions were analysed using total energy (nats), and heart rate was predicted using
ordinary least squares (OLS) and robust linear models (RLM). Pearson correlation evaluated
associations among environmental and physiological factors. Findings: Emotional profiles were
highly individualized, fluctuating within dominant states, with occasional peaks in transition
energy. Interactions among emotions, rather than single emotions, primarily drove total surprisal
energy (OLS R² = 0.89; RLM R² = 0.88). Surprisal energy nonlinearly predicted heart rate (OLS R² =
0.56; RLM R² = 0.55) and combining emotional with environmental factors further improved
predictions (OLS R² = 0.64; RLM R² = 0.53), highlighting robustness to outliers. Originality: By
introducing total emotional energy as a quantitative metric, this study integrates multimodal
affective, physiological, and environmental data, providing a novel framework for emotion aware
safety monitoring, adaptive interventions, and workload management in smart manufacturing
Biobased adsorbents for nitrate and phosphate removal from aqueous solutions
No full textThis thesis investigates the development and application of sustainable, biobased adsorbents for the removal of nutrients (nitrate and phosphate) from water, with a focus on adsorption processes. The research aims to demonstrate that functionalized biopolymer and biochar materials can effectively and safely remove these contaminants, aligning with principles of environmental sustainability and the circular economy.
The primary material studied is a novel cellulose-based anion exchange hydrogel (CAH), synthesized using safer crosslinking and cationizing agents to avoid the toxic compounds typically employed in the production of conventional ion exchange polymers. The CAH exhibited high adsorption capacities for both nitrate and phosphate, with superior performance in nitrate removal. In batch experiments, the CAH achieved 92% nitrate removal and 82% phosphate removal from 15 mg/L solutions, with maximum adsorption capacities of 95 mg/g for nitrate and 63 mg/g for phosphate. It outperformed many other hydrogel-based adsorbents while maintaining stable efficiency across a broad pH range (4–9). Additionally, CAH exceeded the performance of a commercial polystyrene resin in phosphate removal and achieved comparable results for nitrate. Its faster adsorption kinetics were supported by a high swelling ratio of approximately 5 g/g and a water content of 83%. It also demonstrated faster adsorption kinetics for both nutrients. Structural and functional characterization using SEM, FTIR, XRD, BET, zeta potential, and Raman spectroscopy confirmed the hydrogel’s integrity and effectiveness, indicating that nutrient uptake primarily occurs through electrostatic interactions and ion exchange mechanisms.
To evaluate scalability, the CAH was also tested in a continuous fixed-bed column system for nitrate removal. The system demonstrated efficient nitrate removal, with treatment performance influenced by flow rate and influent concentration. At a flow rate of 6 mL/min, the column achieved up to 80% nitrate removal, and the maximum nitrate adsorption capacity reached 162 mg/g based on Thomas model fitting. The Thomas and Yoon-Nelson models effectively described the adsorption kinetics. Notably, the maximum nitrate adsorption capacity of CAH, as determined experimentally and via the Thomas model, outperformed many previously reported adsorbents, highlighting its potential as a high-efficiency material for real-world water treatment applications. The CAH also demonstrated strong regeneration potential for nitrate removal, maintaining its adsorption performance over 10 adsorption–desorption cycles, which highlights its practicality and cost-effectiveness for long-term use.
While CAH offered excellent performance, the need for more accessible and locally adaptable solutions in rural and resource-limited settings motivated the development of a second adsorbent. In such areas, access to high-tech synthesis methods is limited, but agricultural residues are often readily available. Producing an adsorbent from locally sourced agricultural waste using a simple and low-cost modification process offers a viable solution for large-scale deployment. Moreover, utilizing agricultural waste supports sustainable practices and contributes to circular economy goals.
Accordingly, a second material, iron-treated barley straw biochar (Fe-BSBC), was developed and investigated. This is the first study to evaluate Fe-BSBC for nutrient removal through batch adsorption experiments under various conditions. Iron surface modification enhanced the biochar’s properties by forming an iron oxide layer and a well-structured porous network. Fe-BSBC achieved 98% phosphate removal and 82% nitrate removal from 15 mg/L solutions, with adsorption capacities of 22 mg/g for phosphate and 4.07 mg/g for nitrate. Fe-BSBC effectively adsorbed both nutrients, with superior performance for phosphate, likely due to inner-sphere complexation with Fe– OH groups via ligand exchange. In contrast, nitrate adsorption was primarily driven by weaker electrostatic interactions. These findings demonstrate the viability of low-cost, bio-based adsorbents derived from agricultural waste, offering both environmental and economic benefits. Fe-BSBC may serve as a complementary or alternative adsorbent to CAH, expanding the portfolio of sustainable water treatment solutions adaptable to diverse socio-economic contexts.
In general, this thesis advances the development of sustainable water treatment technologies by introducing novel, biodegradable, and non-toxic alternatives to conventional synthetic adsorbents. It offers practical, scalable, and environmentally responsible solutions that support global efforts toward water sustainability, pollution prevention, and resource recovery
Land use change in Otago’s hill and high country, and implications for indigenous biodiversity: a report to Otago Regional Council, 20 December 2024. EnviroLink Medium Advice Grant 2024.
No full textThe biodiversity landscape we now inhabit is one in which there is very little indigenous habitat
left. Abundance of biodiversity is a key predictor of its vulnerability or resilience to
environmental effects from land development or climate change. The more of something there
is, the less vulnerable it is as a whole.
A plain-English description of ecological vulnerability says a species, community, or ecosystem
is vulnerable if some aspect of its situation or biology renders it susceptible to disturbance.
Much has been written about aspects of Aotearoa - New Zealand’s (Aotearoa NZ’s) biology that
makes our biodiversity vulnerable to invasive species amongst other threats. This report is not
about the biology of Otago’s biodiversity. Rather, this report is about the situation of Otago’s
biodiversity.
At each of the 4 major inflection points in the past 35 years – tenure review, Nature Heritage
Fund purchases, Queen Elizabeth II National Trust (QEII) covenants, and Recommended Areas
for Protection – the least threatened environments were protected and the most threatened
environments were freeholded. This pattern of land ownership change and its resulting land
use change will make Otago’s biodiversity more vulnerable, not less. This vulnerability means
protecting what is left of Otago’s biodiversity has never been more important.
All of this puts Otago’s biodiversity in a situation of vulnerability. This reports leverages
knowledge about recent historical decisions and the resulting current biodiversity situation to
strategise maintenance of biodiversity on a regional scale to achieve the objective of Resource
Management Act (RMA) and the National Policy Statement on Indigenous Biodiversity (NPSIB)
Assessing variability in cone production in a Pinus radiata seed orchard,
No full textThis study examines how tree age, clone identity and site conditions influence the production of cones in a Pinus radiata seed orchard located near the Wairau River mouth in Blenheim. The orchard consists of two contrasting environments: the riverside, dominated by compact fine silts formed from periodic flooding of the river and the seaside, dominated by large rocks and sand. Nine blocks of importance to PF Olsen were selected for a full tree-level cone count in 2024-2025. Historical data from 2015 to the present time was made available to complement the data collection. The data was used to assess production patterns and test six sampling methods to reduce time spent collecting from the full orchard while still retaining acceptable accuracy.
Across the duration of the study period, the seaside generally produced a higher number of cones per tree than the riverside. However, year-to-year variability was very prominent, and clear clone-by-environment trends were not definitive. Age effects were also inconclusive over the study window; production did not show a consistent decline or increase with age, rather a cyclical pattern was seen, which is consistent with existing literature. There are also no definitive trends with clone identity and production, as the rankings change across years, except for the clone in genotype F, which has frequently produced the most cones.
To improve operational efficiency, six sampling approaches were simulated at different intensity levels ranging from 18% to 100% of the population. The systematic row with random tree method consistently performed the best, achieving an accuracy of 90% by sampling 50% of the population, relative to the full block mean. Larger gains were observed with higher quantities of rows rather than more trees, increasing the spatial coverage. Two very low-yield blocks producing 0.71 and 1.77 cones, depressed accuracy metrics; excluding them increases average accuracy by 2.8%. With a full measure of the population, including all rows and all trees, accuracy reached 93.6%, and 96.0% when low-yield blocks were removed. The implementation of a systematic row with a random tree, sampling 50% of the population, would reduce the collection time by half, with only an approximate 10% loss in accuracy compared to a complete count. This would greatly improve the productivity and operational efficiency of the orchard, supporting the goal of reliable planning for future operations based on accurate cone production estimates