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Research papers, The University of Auckland Library

This thesis revisits the topic of earthquake recovery in Christchurch City more than a decade after the Canterbury earthquakes. Despite promising visions of a community reconnected and a sustainable and liveable city, significant portions of the city’s core – the Red Zone – remain dilapidated and “eerily empty”. At the same time, new developments in other areas have proven to be alienated or underutilised. Currently, the Canterbury Earthquake Recovery Authority’s plans for the rebuilding highlight the delivery of more residential housing to re-populate the city centre. However, prevalent approaches to housing development in Christchurch are ineffective for building an inclusive and active community. Hence, the central inquiry of the thesis is how the development of housing complexes can revitalise the Red Zone within the Christchurch city centre. The inquiry has been carried out through a research-through-design methodology, recognising the importance of an in-depth investigation that is contextualised and combined with the intuition and embodied knowledge of the designer. The investigation focuses on a neglected site in the Red Zone in the heart of Christchurch city, with significant Victorian and Edwardian Baroque heritage buildings, including Odeon Theatre, Lawrie & Wilson Auctioneers, and Sol Square, owned by The Regional Council Environment Canterbury. The design inquiry argues, develops, and is carried through a place-assemblage lens to housing development for city recovery, which recognizes the significance of socially responsive architecture that explores urban renewal by forging connections within the social network. Therefore, place-assemblage criteria and methods for developing socially active and meaningful housing developments are identified. Firstly, this thesis argues that co-living housing models are more focused on people relations and collective identity than the dominant developer-driven housing rebuilds, as they prioritise conduits for interaction and shared social meaning and practices. Secondly, the adaptive reuse of derelict heritage structures is proposed to reinvigorate the urban fabric, as heritage is seen to be conceived as and from a social assemblage of people. The design is realised by the principles outlined in the ICOMOS charter, which involves incorporating the material histories of existing structures and preserving the intangible heritage of the site by ensuring the continuity of cultural practices. Lastly, design processes and methods are also vital for place-sensitive results, which pay attention to the site’s unique characteristics to engage with local stakeholders and communities. The research explores place-assemblage methods of photographic extraction, the drawing of story maps, precedent studies, assemblage maps, bricolages, and paper models, which show an assembly of layers that piece together the existing heritage, social conduits, urban commons and housing to conceptualise the social network within its place

Audio, Radio New Zealand

Is Christchurch about to dethrone Wellington as the country's new capital of cool? Locals say Otautahi is becoming a hipper, more culturally vibrant place after it was devastated by earthquakes more than a decade ago. University students are coming in their droves, with the city offering affordability and an abundance of things to do, Adam Burns reports.

Research papers, The University of Auckland Library

The seismic tremor that shook Christchurch on February 22, 2011, not only shattered buildings but also the spirit of the city’s residents. Amidst the ruins, this design-focused thesis unravels two intertwining narratives, each essential to the city’s resurrection. At its core, this thesis probes the preservation of Christchurch’s memory and character, meticulously chronicling the lost heritage architecture and the subsequent urban metamorphosis. Beyond bricks and mortar, it also confronts the silent aftershocks - the pervasive mental health challenges stemming from personal losses and the disfigured cityscape. As a native of Christchurch, intimately connected to its fabric, my lens reflects not just on the architectural reconstruction but also on the emotional reconstruction. My experience as an autistic individual, a recently discovered facet of my identity, infuses this design journey with a distinct prism through which I perceive and interact with the world. The colourful sketches that drive the design process aren’t mere illustrations but manifestations of my interpretation of spaces and concepts, evoking joy and vitality—a testament to embracing diversity in design. Drawing parallels between healing my own traumas with my colourful and joyful neurodivergent worldview, I’ve woven this concept into proposals aimed at healing the city through whimsy, joy, and vibrant colours. Personal experiences during and post-earthquakes profoundly shape my design proposals. Having navigated the labyrinth of my own mental health amid the altered cityscape, I seek avenues for reconciliation, both personal and communal. The vibrant sketches and designs presented in this thesis encapsulate this vision—a fusion of vivid, unconventional interpretations and a dedication to preserving the essence of the original cityscape while still encouraging movement into the future

Research papers, University of Canterbury Library

Picture this, you are relaxing at home enjoying the afternoon sun. It is another beautiful Christchurch day in late 2017. There is a knock at the door, you’ve been expecting it. It is a member of the Christchurch Health and Development Study, here to conduct your prearranged interview. The interview request did not come as a surprise of course, you have been participating in these interviews yourself sporadically throughout your adult life, and prior to that you attended many alongside your parents. In fact, you have been answering the studies interview your whole life. Transcripts of these interviews sit in the studies database alongside copies of school reports, health records and a wealth of other information. It has been this way since birth, since your mother was approached back in 1977, not long after you had arrived in this world, and asked if she would consent to participating in the study. She, along with many other Cantabrian new mothers from that year, agreed and the Christchurch Health and Development Study was born. Since then, these interviews have become a matter of routine for you. As life went on many things changed, but one thing that was constant was the sporadic visit from an interviewer of the study. The current interview is a little different from most of the others, however. Last time an interviewer visited in 2012, you were asked if you would like to conduct an earthquake-specific interview, you agreed. This time, the same question was asked. Why? Well because you were there that day of course. The day of the 22nd February 2011 when a major earthquake struck Canterbury. You were there in the centre of the city as buildings came crashing down and people ran for safety. You were there for the chaos. Your knee dully aches, it never did quite heal properly and strangely seems to flare up whenever you think back to that day. A lasting reminder. It is a difficult subject, but you agree to the second earthquake-specific interview. You understand the purpose of the study, and the value of the data collected. You take a sip of the cup of tea politely made upon the interviewer’s arrival, lean back into the comfort of your couch and cast your mind back to that fateful day. So, what does this study mean? Why still participate, all these years later? Over time it has become more apparent as to how valuable this information could be, considering all the experiences through the life course, and to think of the experiences that others in the cohort have had too. How differently have events affected people from all walks of life, who just so happened to be born within the same few months. We can use the data from this study to better understand situations when using life course characteristics which can hopefully influence decision making and population health within New Zealand.

Research papers, University of Canterbury Library

From small coastal settlements to large cities, communities are exposed to both the direct and indirect consequences of climate-change induced sea-level rise (SLR). Above the ground surface, short- and long-term coastal effects of SLR are visible and cause damage from flooding, erosion, and loss of habitats and ecosystems. Below the ground surface, the effects are less visible but nonetheless extensive. Groundwater is present at shallow depth in the coastal zone and the effects of SLR on shallow groundwater threaten water security, agricultural production and infrastructure. Groundwater flooding, a hydrological hazard results from the process of water table rise, where the groundwater surface intersects or goes above the land surface due to changing conditions. The coastal zone is a complex dynamic space between saltwater and freshwater environments above and below the ground surface, and coastal groundwater hazards are intensified due to SLR. However, current monitoring of coastal shallow groundwater levels and salinity does not occur sufficiently to mitigate and adapt to the groundwater hazard. This thesis provides insights into the dynamics of coastal shallow groundwater, urban monitoring networks, simulations of water table rise and the issues posed by shallow groundwater changes driven by SLR and effects on flooding. The first study reviewed processes of coastal groundwater rise and simulation tools used to evaluate possible impacts of SLR. The benefits and limitations of the two main methods to assess coastal groundwater rise and its contribution to flooding - spatial interpolation and numerical tools - were discussed. The review highlighted the need for methodology comparisons between spatial interpolation and numerical tools to guide future work. The simulation tools that are used to evaluate changes in urban hydrogeology due to SLR do not specifically estimate groundwater flooding. Current monitoring practices do not capture evidence for groundwater rise with SLR. Therefore, the assessment methods need to rely on improved coastal groundwater monitoring networks focused on water quality, saltwater intrusion, and continuous groundwater levels records near the coastline, tidally influenced surface water bodies, and critical infrastructure. The second study focused on an urban shallow groundwater monitoring network and assessed its development, current physical condition and usefulness for SLR research. Following the 2010-2011 Canterbury Earthquake Sequence, in Otautahi Christchurch, ¯ Aotearoa New Zealand, shallow groundwater data acquisition and establishment of a geotechnical database provided unprecedented information on subsurface conditions. The monitoring infrastructure provided high spatio-temporal resolution records of shallow groundwater levels, which opened the field of New Zealand-based urban groundwater studies. Field surveys and digital information reviews showed that the monitoring net work was in overall good condition and robust, despite some maintenance issues. The dataset held by the city and regional councils should be more widely used to benefit the community, urban water management, researchers and practitioners, facing decisions to adapt and protect coastal areas from the impacts of climate change and SLR. The third study determined characteristics of shallow groundwater, including spatial and temporal trends in depths to groundwater and their relationship to natural and an thropogenic stressors. The study used depth to groundwater measurements from the uniquely extensive and densely spaced monitoring network in Otautahi Christchurch, ¯ Aotearoa New Zealand. Data-driven analysis approaches were applied, including spa tial interpolation, autocorrelation, clustering, cross-correlation, and trend analysis. This comprehensive approach revealed discernible clusters and trends within the dataset, pro viding valuable insights into the spatial and temporal variability of shallow groundwater in urban coastal settings. Responses to stresses such as rainfall events and stream flow were successfully classified using clustering analysis, while anthropogenic influences were more challenging. The primary feature in hydrograph classification proved to be the prox imity to tidal rivers and their correlation with tidal signals. This study highlighted the importance of monitoring coastal groundwater and the need for a better understanding of its effects on urban infrastructure and the built environment. The fourth study focused on simulating the effects of SLR on water table rise. These processes may lead to groundwater flooding and infrastructure challenges. A numerical model was used to assess the transient water table movement in response to SLR. Various SLR scenarios and rates were used to simulate the magnitudes and rates of water table rise, considering a range of aquifer parameters for both fixed-head and fixed-flux inland boundary conditions. The magnitudes and rates of water table rise were always less than but proportional to SLR and decreased with distance from the coastline. The magnitude and rate of water table rise in response to SLR were the largest for fixed flux inland boundary conditions, but it takes a long time for conditions to equilibrate. Fixed-flux conditions were found to pose a greater hazard as the maximum impact may not be experienced for decades, posing challenges to planners and managers of coastal groundwater systems. Adding a drain reduced the magnitude and rate of water table rise, more on the inland side than on the coastal side. The final study examined the key impacts of SLR on coastal shallow groundwater, and subsequent challenges faced by infrastructure asset managers. The study showed that current and future issues such as saltwater intrusion, flooding, and earthquake liquefaction hazard due to groundwater are exacerbated by climate change-driven SLR. A key issue is determining who will take responsibility for shallow groundwater management in areas with multiple and overlapping local government jurisdictions. Another key finding is that current techniques to manage groundwater in infrastructure construction/operation and land management will be applied in future, and challenges to coastal infrastructure adaptation will be posed by political and economic considerations rather than technical understanding.

Research papers, The University of Auckland Library

The research presented in this thesis investigated the environmental impacts of structural design decisions across the life of buildings located in seismic regions. In particular, the impacts of expected earthquake damage were incorporated into a traditional life cycle assessment (LCA) using a probabilistic method, and links between sustainable and resilient design were established for a range of case-study buildings designed for different seismic performance objectives. These links were quantified using a metric herein referred to as the seismic carbon risk, which represents the expected environmental impacts and resource use indicators associated with earthquake damage during buildings’ life. The research was broken into three distinct parts: (1) a city-level evaluation of the environmental impacts of demolitions following the 2010/2011 Canterbury earthquake sequence in New Zealand, (2) the development of a probabilistic framework to incorporate earthquake damage into LCA, and (3) using case-study buildings to establish links between sustainable and resilient design. The first phase of the research focused on the environmental impacts of demolitions in Christchurch, New Zealand following the 2010/2011 Canterbury Earthquake Sequence. This large case study was used to investigate the environmental impact of the demolition of concrete buildings considering the embodied carbon and waste stream distribution. The embodied carbon was considered here as kilograms of CO2 equivalent that occurs on production, construction, and waste management stage. The results clearly demonstrated the significant environmental impacts that can result from moderate and large earthquakes in urban areas, and the importance of including environmental considerations when making post-earthquake demolition decisions. The next phase of the work introduced a framework for incorporating the impacts of expected earthquake damage based on a probabilistic approach into traditional LCA to allow for a comparison of seismic design decisions using a carbon lens. Here, in addition to initial construction impacts, the seismic carbon risk was quantified, including the impacts of seismic repair activities and total loss scenarios assuming reconstruction in case of non-reparability. A process-based LCA was performed to obtain the environmental consequence functions associated with structural and non-structural repair activities for multiple environmental indicators. In the final phase of the work, multiple case-study buildings were used to investigate the seismic consequences of different structural design decisions for buildings in seismic regions. Here, two case-study buildings were designed to multiple performance objectives, and the upfront carbon costs, and well as the seismic carbon risk across the building life were compared. The buildings were evaluated using the framework established in phase 2, and the results demonstrated that the seismic carbon risk can significantly be reduced with only minimal changes to the upfront carbon for buildings designed for a higher base shear or with seismic protective systems. This provided valuable insight into the links between resilient and sustainable design decisions. Finally, the results and observations from the work across the three phases of research described above were used to inform a discussion on important assumptions and topics that need to be considered when quantifying the environmental impacts of earthquake damage on buildings. These include: selection of a non-repairable threshold (e.g. a value beyond which a building would be demolished rather than repaired), the time value of carbon (e.g. when in the building life the carbon is released), the changing carbon intensity of structural materials over time, and the consideration of deterministic vs. probabilistic results. Each of these topics was explored in some detail to provide a clear pathway for future work in this area

Research papers, Victoria University of Wellington

Sea level rise is one consequence of Earth’s changing climate. Century-long tide gauge records show that global-mean sea-level rise reached 11-16 cm during the twentieth century at a mean rate of 1.2 mm/y. Today, the average rate of global-mean sea-level rise is higher at 3-4 mm/y and is expected to increase in the future. This represents a hazard to low elevation coastal zones worldwide. Yet, before global sea level projections can be used to characterise future coastal flood hazard at a local scale, the effects of tectonics (and other processes) that drive vertical land motion (VLM) must be considered. VLM is defined as the vertical velocity (uplift or subsidence) of the solid surface with respect to the centre of Earth. In this study, new VLM maps are generated over coastal strips in New Zealand, using Sentinel-1 InSAR and GNSS data. In New Zealand, measuring VLM using InSAR on naturally vegetated or agricultural land is difficult due to signal decorrelation. Along the rural Bay of Plenty coastal strip, I use a persistent-scatterer approach to generate a VLM map from both east-looking ascending and west-looking descending Sentinel-1 data between 2015-2021. Using time-series data over the same time period from a dense network of 20 GNSS sensors, I tie InSAR-derived line-of-sight velocity to the 2014 ITRF reference frame. I test two different methods for measuring VLM and compare the results against GNSS vertical velocity along the Bay of Plenty coast. Best results are achieved by first removing the interpolated horizontal GNSS velocity field from each of the InSAR datasets, before averaging the two VLM estimates. Measured VLM is between -3 and 3 mm/y, with negative values (subsidence) occurring within the low-lying Rangitāiki Plain and Ōpōtiki valley, and uplift across the elevated region west of Matatā. This thesis integrates geomorphological, geological, and historical levelling VLM records with modern satellite datasets to assess VLM across timescales ranging from 10 to 100,000 years at Matatā. Uplift rate has been variable through time, with average uplift over the last 300,000 years of 1 mm/y, 4.5 mm/y since 1720 years, 2 mm/y between 1950-1978, and 10 mm/y between 2004-2011. Previous modelling has shown that the best fit to the 2004-2011 rapid uplift rates is an inflating magmatic source at ~10 km depth beneath Matatā. To reconcile all data, I present a VLM model that consists of short-lived periods (7 years) of rapid uplift (10 mm/y), separated by longer periods (30 years) of lower background uplift (3 mm/y). The episodic nature of VLM at Matatā likely reflects short-lived periods of magmatic intrusion. Episodic VLM characterised by large rates of uplift (10 mm/y) has been seen at Taupō volcano, and other volcanic centers globally. It has been 12 years since the end of the last intrusion episode; this modelling suggest one may expect to observe increased uplift rates at Matatā in the coming decades. Densely populated urban coastal strips are most at risk from the effects of relative sea-level rise. At the same time, anthropogenic activities associated with urbanization, such as groundwater withdrawal, and land reclamation can lead to local land subsidence (LLS), further exacerbating the risk to urban infrastructure. LLS refers to subsidence relative to nearby land area assumed to be stable. In this thesis, I create the first high-resolution (10 m) maps of LLS at six urban coastal strips in New Zealand, with a combined length of 285 km, using Sentinel-1 InSAR data between 2018-2021. This analysis reveals 89% of urban coastal strips are subsiding at rates of -0.5 mm/y or greater, and 11% is subsiding at higher rates of -3.0 mm/y or greater. On average, subsidence is -0.6 to -2.9 mm/y higher at the coastal strip, compared to inland areas occupied by GNSS stations. This analysis also documents highly-localised hotspots of LLS, with subsidence rates of up to -15 mm/y. In Christchurch, rapid and localised subsidence (-8 mm/y) is observed within coastal suburbs New Brighton and Southshore. In most cities, the highest subsidence rates occur on land reclaimed in the early-late twentieth century, and in areas built on Holocene sediment. Time-series analysis of LLS at sites of reclaimed land shows both linear and non-linear rates of deformation over time periods of up to 6-8 years. This thesis highlights the variable exposure to relative sea-level rise of New Zealand coastal strips, and demonstrates that in many cases current rates of VLM should be expected to continue for the next few decades.