As far as suburbs with bad reputations go, Aranui in Christchurch often seems to dominate local public perceptions. High crime, high unemployment, low incomes, run-down state houses and uncared-for neighbourhoods have been the key words and phrases used over many decades. This reputation achieved national standing over the same period and in 2001 Aranui gained the dubious distinction of becoming the pilot project for the Labour Government’s state housing Community Renewal Programme initiated in 2001. It is common to read “Don’t buy or rent here” comments on websites and blogs advising prospective immigrants on where to live. One of the dispiriting moments in Aranui’s history came in September 2009 with the discovery of two bodies under the floorboards of a Hampshire Street property and the subsequent charge of double-homicide and conviction of local resident Jason Somerville for the murder of his wife Rebecca Chamberlain and neighbour Tisha Lowry.
The world is constantly changing. Christchurch, New Zealand, has recently experienced drastic changes after earthquakes struck the city. The earthquakes caused the city to physically shake, and the land to sink in some places and rise in others. Now further change is forcast and parts of Christchurch could be under water by 2115 according to experts.
Climate change induced sea level rise is recognised as a international issue with potential impacts for coastal communities all over the world. The Chrischtchurch City Council is required to have a 100-year planning horizon for sea level rise and this means planning for at least one meter, and possibly up to two meters, of sea level rise by 2115. This dissertation investigates the planning response to slow onset disasters, change, and uncertainty, using the example of sea-level rise in Christchurch, and it examines the role of public participation in this. To achieve this, the ways in which planning theory and practice acknowledge uncertainty, and cope with change, were critically analysed along with the Christchurch City Council’s response to the Tonkin and Taylor predictions and modelling. Semi-structured interviews with professionals in natural hazards risk reduction, policy, and planning were conducted, and the previous and proposed Christchurch City District Plans were compared.
Planning for sea level rise in Christchurch provides an example of how planners may cope with slow onset change. The results of this dissertation suggests that the favoured risk reduction strategy for coastal communities in Christchurch is an adaptation strategy, and at present there is no sign of managed retreat being employed. The results also suggests using a planning approach that involves public participation for best results when planning for change, uncertainty or slow onset disasters.
Brooklands Lagoon / Te Riu o Te Aika Kawa (‘Brooklands’) is an important wetland and estuarine ecosystem in Canterbury. It is a site of cultural significance to Ngāi Tūāhuriri, and is also valued by the wider community. Home to an array of life, it is connected to the Pūharakekenui/Styx and Waimakariri rivers, and is part of a wetland landscape complex that includes the Avon-Heathcote / Ihutai estuary to the south and the Ashley / Rakahuri estuary to the north. Notionally situated within the territorial boundary of Christchurch City Council and jurisdictionally encompassed by the regional council Environment Canterbury, it has been legally determined to be part of the coastal marine area. The complicated administrative arrangements for the lagoon mirror the biophysical and human challenges to this surprisingly young ecosystem since its formation in 1940.
Here we present a synthesis of the historical events and environmental influences that have shaped Brooklands Lagoon. Before existing as an intertidal ecosystem, the Waimakariri river mouth was situated in what is now the southern end of the lagoon. A summary timeline of key events is set out in the table below. These included the diversion of the Waimakariri River mouth via the construction of Wrights Cut in the 1930s, which influenced the way that the lower reaches of the river interacted with the land and sea. A large flood in 1940 shifted the river mouth ~2 to 3 kilometres north, that created the landscape that we see today. However, this has not remained stable, as the earthquake sequence in 2010 and 2011 subsided the bed of the estuary.
The changes are ongoing, as sea level rise and coastal inundation will place ongoing pressure on the aquatic ecosystem and surrounding land. How to provide accommodation space for Brooklands as an estuary will be a key planning and community challenge, as Environment Canterbury begins the engagement for the review of its Regional Coastal Plan. There is also a requirement to safeguard its ecological health under the 2020 National Policy Statement on Freshwater Management. This will necessitate an integrated mountains to sea (ki uta ki tai) management approach as the lagoon is affected by wider catchment activities. We hope that this report will contribute to, and inform these processes by providing a comprehensive historical synthesis, and by identifying considerations for the future collaborative management of Brooklands Lagoon, and protection of its values. In essence, we suggest that Te Riu o Te Aika Kawa deserves some sustained aroha.
Creative temporary or transitional use of vacant urban open spaces is
seldom foreseen in traditional urban planning and has historically been
linked to economic or political disturbances. Christchurch, like most
cities, has had a relatively small stock of vacant spaces throughout
much of its history. This changed dramatically after an earthquake and
several damaging aftershocks hit the city in 2010 and 2011; temporary
uses emerged on post-earthquake sites that ran parallel to the “official”
rebuild discourse and programmes of action. The paper examines
a post-earthquake transitional community-initiated open space (CIOS)
in central Christchurch. CIOS have been established by local community
groups as bottom-up initiatives relying on financial sponsorship,
agreements with local landowners who leave their land for temporary
projects until they are ready to redevelop, and volunteers who build
and maintain the spaces. The paper discusses bottom-up governance
approaches in depth in a single temporary post-earthquake community
garden project using the concepts of community resilience and social
capital. The study analyses and highlights the evolution and actions of
the facilitating community organisation (Greening the Rubble) and the
impact of this on the project. It discusses key actors’ motivations and
values, perceived benefits and challenges, and their current involvement
with the garden. The paper concludes with observations and recommendations about the initiation of such projects and the challenges for those wishing to study ephemeral social recovery phenomena.
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.
