Today there is interest in building resilient communities. Identifying and managing the risks of natural hazards with communities who face compounding hazards is challenging. Alpine ski areas provide a unique context to study this challenging and complex process. The traditional approach taken to manage natural hazards is discipline-centric and focuses on common (e.g. high probability low consequence) natural hazards such as avalanches. While this thesis acknowledges that the common approach is rational, it argues that we can extend our communities of practice to include rare (e.g. low probability / high consequence) natural hazards such as earthquakes. The dynamically complex nature of these ‘rare’ hazards limits our understanding about them, but by seeking and using the lived experiences of people in mountain communities some knowledge can be gained to help improve our understanding of how to adapt. This study focuses on such an approach in the context of alpine ski areas prone to earthquakes as a first step toward identifying key policy opportunities for hazard mitigation in general.
The contributions can be broken down into methodological, contextual, and theoretical pursuits, as well as opportunities for improving future research. A development mixed method triangulated approach was justified because the research problem (i.e. earthquakes in ski areas) has had little consideration. The context provided the opportunity to test the integration of methods while dealing with the challenges of research in a novel context. Advancement to fuzzy cognitive mapping was achieved through the use of unsupervised neural networks (Self-organizing Maps or Kohonen Maps). The framework applied in the multi-site case study required a synthesis of current approaches, advances to methods and a functional use of cultural theory. Different approaches to participatory policy development were reviewed to develop a research protocol that was accessible.
Cultural theory was selected as a foundation for the thesis because of its’ preference for plural rationalities from five ways of organizing. Moreover, the study undertook a shift away from the dichotomy of ‘methodological individualism’ and ‘methodological collectivism’ and instead chose the dividual (i.e. social solidarities that consist of culural biases, behavioral strategies and social relations) as a consistent unit of analysis despite three different methodologies including: field studies, qualitative interviews, and fuzzy cognitive maps. In this sense, the thesis sought to move away from ‘elegant solutions’ from singular solidarities or methods toward a research philosophy that sustains requisite variety and clumsy solutions. Overall the approach was a trandisciplinary framework that is a step toward sustainable hazards mitigation.
The results indicate that the selections of risks and adaptation strategies associated with the in-situ hazards are driven by roles that managers, workers, and riders play in the context. Additionally, fuzzy cognitive maps were used as an extension of qualitative interviews and demonstrated the potential for power struggles that may arise between participant groups when considering strategies for preparation, response and recovery. Moreover, the results stress that prolonged engagement with stakeholders is necessary to improve the policy development process. Some comments are made on the compatibility condition of congruence between cultural biases, behavioural strategies, and social relations. As well, inclusion of the hermit/autonomous solidarities is stressed as a necessary component of future applications of cultural theory. The transdisciplinary mixed-method framework is an approach that can be transferred to many other vital areas of research where integration is desirable.
Prognostic modelling provides an efficient means to analyse the coastal environment and provide effective knowledge for long term urban planning. This paper outlines how the use of SWAN and Xbeach numerical models within the ESRI ArcGIS interface can simulate geomorphological evolution through hydrodynamic forcing for the Greater Christchurch coastal environment. This research followed the data integration techniques of Silva and Taborda (2012) and utilises their beach morphological modelling tool (BeachMM tool). The statutory requirements outlined in the New Zealand Coastal Policy Statement 2010 were examined to determine whether these requirements are currently being complied with when applying the recent sea level rise predictions by the Intergovernmental Panel on Climate Change (2013), and it would appear that it does not meet those requirements. This is because coastal hazard risk has not been thoroughly quantified by the installation of the Canterbury Earthquake Recovery Authority (CERA) residential red zone. However, the Christchurch City Council’s (CCC) flood management area does provide an extent to which managed coastal retreat is a real option. This research assessed the effectiveness of the prognostic models, forecasted a coastline for 100 years from now, and simulated the physical effects of extreme events such as storm surge given these future predictions. The results of this research suggest that progradation will continue to occur along the Christchurch foreshore due to the net sediment flux retaining an onshore direction and the current hydrodynamic activity not being strong enough to move sediment offshore. However, inundation during periods of storm surge poses a risk to human habitation on low lying areas around the Avon-Heathcote Estuary and the Brooklands lagoon similar to the CCC’s flood management area. There are complex interactions at the Waimakariri River mouth with very high rates of accretion and erosion within a small spatial scale due to the river discharge. There is domination of the marine environment over the river system determined by the lack of generation of a distinct river delta, and river channel has not formed within the intertidal zone clearly. The Avon-Heathcote ebb tidal delta aggrades on the innner fan and erodes on the outer fan due to wave domination. The BeachMM tool facilitates the role of spatial and temporal analysis effectively and the efficiency of that performance is determined by the computational operating system.
Millions of urban residents around the world in the coming century will experience severe landscape change – including increased frequencies of flooding due to intensifying storm events and impacts from sea level rise. For cities, collisions of environmental change with mismatched cultural systems present a major threat to infrastructure systems that support urban living. Landscape architects who address these issues express a need to realign infrastructure with underlying natural systems, criticizing the lack of social and environmental considerations in engineering works. Our ability to manage both society and the landscapes we live in to better adapt to unpredictable events and landscape changes is essential if we are to sustain the health and safety of our families, neighbourhoods, and wider community networks.
When extreme events like earthquakes or flooding occur in developed areas, the feasibility of returning the land to pre-disturbance use can be questioned. In Christchurch for example, a large expanse of land (630 hectares) within the city was severely damaged by the earthquakes and judged too impractical to repair in the short term. The central government now owns the land and is currently in the process of demolishing the mostly residential houses that formed the predominant land use. Furthermore, cascading impacts from the earthquakes have resulted in a general land subsidence of .5m over much of eastern Christchurch, causing disruptive and damaging flooding. Yet, although disasters can cause severe social and environmental distress, they also hold great potential as a catalyst to increasing adaption. But how might landscape architecture be better positioned to respond to the potential for transformation after disaster?
This research asks two core questions: what roles can the discipline of landscape architecture play in improving the resilience of communities so they become more able to adapt to change? And what imaginative concepts could be designed for alternative forms of residential development that better empower residents to understand and adapt the infrastructure that supports them?
Through design-directed inquiry, the research found landscape architecture theory to be well positioned to contribute to goals of social-ecological systems resilience. The discipline of landscape architecture could become influential in resilience-oriented multi disciplinary collaborations, with our particular strengths lying in six key areas: the integration of ecological and social processes, improving social capital, engaging with temporality, design-led innovation potential, increasing diversity and our ability to work across multiple scales. Furthermore, several innovative ideas were developed, through a site-based design exploration located within the residential red zone, that attempt to challenge conventional modes of urban living – concepts such as time-based land use, understanding roads as urban waterways, and landscape design and management strategies that increase community participation and awareness of the temporality in landscapes.
Saltwater Forest is a Dacrydium cupressinum-dominated lowland forest covering 9000 ha in south Westland, South Island, New Zealand. Four thousand hectares is managed for sustainable production of indigenous timber. The aim of this study was to provide an integrated analysis of soils, soil-landform relationships, and soil-vegetation relationships at broad and detailed scales. The broad scale understandings provide a framework in which existing or future studies can be placed and the detailed studies elucidate sources of soil and forest variability.
Glacial landforms dominate. They include late Pleistocene lateral, terminal and ablation moraines, and outwash aggradation and degradation terraces. Deposits and landforms from six glacial advances have been recognised ranging from latest Last (Otira) Glaciation to Penultimate (Waimea) Glaciation. The absolute ages of landforms were established by analysis of the thickness and soil stratigraphy of loess coverbeds, augmented with radiocarbon dating and phytolith and pollen analysis.
In the prevailing high rainfall of Westland soil formation is rapid. The rate of loess accretion in Saltwater
Forest (ca. 30 mm ka⁻¹) has been low enough that soil formation and loess accretion took place contemporaneously. Soils formed in this manner are known as upbuilding soils. The significant difference between upbuilding pedogenesis and pedogenesis in a topdown sense into an existing sediment body is that each subsoil increment of an upbuilding soil has experienced processes of all horizons above. In Saltwater Forest subsoils of upbuilding soils are strongly altered because they have experienced the extremely acid environment of the soil surface at some earlier time. Some soil chronosequence studies in Westland have included upbuilding soils formed in loess as the older members of the sequence. Rates and types of processes inferred from these soils should be reviewed because upbuilding is a different pedogenic pathway to topdown pedogenesis.
Landform age and morphology were used as a primary stratification for a study of the soil pattern and nature of soil variability in the 4000 ha production area of Saltwater Forest. The age of landforms (> 14 ka) and rapid soil formation mean that soils are uniformly strongly weathered and leached. Soils include Humic Organic Soils, Perch-gley Podzols, Acid Gley Soils, Allophanic Brown Soils, and Orthic or Pan Podzols. The major influence on the nature of soils is site hydrology which is determined by macroscale features of landforms (slope, relief, drainage density), mesoscale effects related to position on landforms, and microscale influences determined by microtopography and individual tree effects. Much of the soil variability arises at microscales so that it is not possible to map areas of uniform soils at practical map scales. The distribution of soil variability across spatial scales, in relation to the intensity of forest management, dictates that it is most appropriate to map soil complexes with boundaries coinciding with landforms.
Disturbance of canopy trees is an important agent in forest dynamics. The frequency of forest disturbance in the production area of Saltwater Forest varies in a systematic way among landforms in accord with changes in abundance of different soils. The frequency of forest turnover is highest on landforms with the greatest abundance of extremely poorly-drained Organic Soils. As the abundance of better-drained soils increases the frequency of forest turnover declines. Changes in turnover frequency are reflected in the mean size and density of canopy trees (Dacrydium cupressinum) among landforms. Terrace and ablation moraine landforms with the greatest abundance of extremely poorly-drained soils have on average the smallest trees growing most densely. The steep lateral moraines, characterised by well drained soils, have fewer, larger trees. The changes manifested at the landform scale are an integration of processes operating over much shorter range as a result of short-range soil variability. The systematic changes in forest structure and turnover frequency among landforms and soils have important implications for sustainable forest management.
Mitigating the cascade of environmental damage caused by the movement of excess reactive nitrogen (N) from land to sea is currently limited by difficulties in precisely and accurately measuring N fluxes due to variable rates of attenuation (denitrification) during transport. This thesis develops the use of the natural abundance isotopic composition of nitrate (δ15N and δ18O of NO₃-) to integrate the spatialtemporal variability inherent to denitrification, creating an empirical framework for evaluating attenuation during land to water NO₃- transfers. This technique is based on the knowledge that denitrifiers kinetically discriminate against 'heavy' forms of both N and oxygen (O), creating a parallel enrichment in isotopes of both species as the reaction progresses. This discrimination can be quantitatively related to NO₃- attenuation by isotopic enrichment factors (εdenit). However, while these principles are understood, use of NO₃- isotopes to quantify denitrification fluxes in non-marine environments has been limited by, 1) poor understanding of εdenit
variability, and, 2) difficulty in distinguishing the extent of mixing of isotopically distinct sources from the
imprint of denitrification. Through a combination of critical literature analysis, mathematical modelling, mesocosm to field scale experiments, and empirical studies on two river systems over distance and time, these short comings are parametrised and a template for future NO₃- isotope based attenuation measurements
outlined.
Published εdenit values (n = 169) are collated in the literature analysis presented in Chapter 2. By evaluating these values in the context of known controllers on the denitrification process, it is found that the magnitude of εdenit, for both δ15N and δ18O, is controlled by, 1) biology, 2) mode of transport through the denitrifying zone (diffusion v. advection), and, 3) nitrification (spatial-temporal distance between nitrification and denitrification). Based on the outcomes of this synthesis, the impact of the three factors identified as controlling εdenit are quantified in the context of freshwater systems by combining simple mathematical modelling and lab incubation studies (comparison of natural variation in biological versus physical expression). Biologically-defined εdenit, measured in sediments collected from four sites along a temperate stream and from three tropical submerged paddy fields, varied from -3‰ to -28‰ depending on the site’s antecedent carbon content. Following diffusive transport to aerobic surface water, εdenit was found to
become more homogeneous, but also lower, with the strength of the effect controlled primarily by diffusive distance and the rate of denitrification in the sediments. I conclude that, given the variability in fractionation dynamics at all levels, applying a range of εdenit from -2‰ to -10‰ provides more accurate measurements of attenuation than attempting to establish a site-specific value. Applying this understanding of denitrification's fractionation dynamics, four field studies were conducted to measure denitrification/ NO₃- attenuation across diverse terrestrial → freshwater systems. The development of NO₃- isotopic signatures (i.e., the impact of nitrification, biological N fixation, and ammonia volatilisation on the isotopic 'imprint' of denitrification) were evaluated within two key agricultural regions: New Zealand grazed pastures (Chapter 4) and Philippine lowland submerged rice production (Chapter 5). By measuring the isotopic composition of soil ammonium, NO₃- and volatilised ammonia following the bovine urine deposition, it was determined that the isotopic composition of NO₃ - leached from grazed pastures is defined by the balance between nitrification and denitrification, not ammonia volatilisation. Consequently, NO₃- created within pasture systems was predicted to range from +10‰ (δ15N)and -0.9‰ (δ18O) for non-fertilised fields (N limited) to -3‰ (δ15N) and +2‰ (δ18O) for grazed fertilised fields (N saturated). Denitrification was also the dominant determinant of NO₃- signatures in the Philippine rice paddy. Using a site-specific εdenit for the paddy, N inputs versus attenuation were able to be calculated, revealing that >50% of available N in the top 10 cm of soil was denitrified during land preparation, and >80% of available N by two weeks post-transplanting. Intriguingly, this denitrification was driven by rapid
NO₃- production via nitrification of newly mineralised N during land preparation activities.
Building on the relevant range of εdenit established in Chapters 2 and 3, as well as the soil-zone confirmation that denitrification was the primary determinant of NO₃- isotopic composition, two long-term
longitudinal river studies were conducted to assess attenuation during transport. In Chapter 6, impact and recovery dynamics in an urban stream were assessed over six months along a longitudinal impact gradient using measurements of NO₃- dual isotopes, biological populations, and stream chemistry. Within 10 days of the catastrophic Christchurch earthquake, dissolved oxygen in the lowest reaches was <1 mg l⁻¹, in-stream denitrification accelerated (attenuating 40-80% of sewage N), microbial biofilm communities changed, and several benthic invertebrate taxa disappeared. To test the strength of this method for tackling the diffuse, chronic N loading of streams in agricultural regions, two years of longitudinal measurements of NO₃- isotopes were collected. Attenuation was negatively correlated with NO₃- concentration, and was highly
dependent on rainfall: 93% of calculated attenuation (20 kg NO₃--N ha⁻¹ y⁻¹) occurred within 48 h of rainfall.
The results of these studies demonstrate the power of intense measurements of NO₃- stable isotope for distinguishing temporal and spatial trends in NO₃ - loss pathways, and potentially allow for improved catchment-scale management of agricultural intensification. Overall this work now provides a more cohesive understanding for expanding the use of NO₃- isotopes measurements to generate accurate understandings of the controls on N losses. This information is becoming increasingly important to predict ecosystem response to future changes, such the increasing agricultural intensity needed to meet global food demand, which is occurring synergistically with unpredictable global climate change.
