Lake Rotorua has become increasingly eutrophic over the past 2 to 3 decades. The sediments of the lake have been shown to exert an important influence on this eutrophication process. Chemistry of the sediments has been studied to determine the nature, composition and distribution of elements, through a 1.5 year coring programme. A geophysical survey together with sub-bottom profiling has provided stratigraphic information related to the bathymetry of the lake. Lake Rotorua has two types of sediments: coarse, dense (density c. 0.5 g/cm3) sediments comprised of clastic erosion products and coarse rhyolitic airfall components covering approximately 60% of the lake area; and fine, low-density (approximatly 0.02 g/cm3) diatomaceous ooze that covers the remaining 40% of the lake, accumulated from deposition of biota, predominantly diatom frustules of Aulacoseira granulata. The sediment contains a record of volcanic eruptions, with the Tarawera Tephra typically found 0.5 m below the sediment water interface and Kaharoa Tephra typically between 2 to 3 m depth, in water depths of 10-15 m. Phosphorus concentration in Lake Rotorua sediments decreases with sediment depth. In the centre of the lake phosphorus concentrations in the top 2 cm can exceed 2500 g/tonne and decline to 800 g/tonne at 20 cm depth. Accumulation rate of phosphorus in the sediment based on the nutrient budget is approximatly 29.6 t/yr. Iron and manganese concentrations in the sediment depend on the availability of the element and the sedimentation rate of diatom frustules, and are controlled by the redox conditions in the sediment. The average concentration of iron and manganese in the sediment is approximately 8000 g/tonne and between 300 and 400 g/tonne, respectively. Iron accumulates in the sediment at a rate of 385 t/yr and manganese at 17.9 t/yr. Maximum concentrations of arsenic in the sediment are 250 g/tonne but are generally between 50-100 g/tonne, depending on the water depth. Lead concentrations are typically below 15 g/tonne. Sediment concentrations of both arsenic and lead are highly correlated with iron and manganese concentrations in the sediment and mimic the respective concentration profiles. Arsenic and lead accumulate in the sediment at a rate of 3.71 and 0.49 t/yr, respectively. All elements show a peak in concentration in the tephra layers. The bathymetry of Lake Rotorua is dominated by a curved depression extending from Sulphur Point and almost reaching the Ohau Channel. This depression is probably a structural feature likely associated with the collapse of the caldera, but could be an ancient drainage channel. A series of conical depressions clustered to the north of Sulphur Point and to the east of Mokoia Island are likely to be hydrothermal explosion creators. In the north in the lake at water depths less than 10 m, a series of near-shore terraces are preserved in the sediment. Sub-bottom echo-sounding shows no return of sonic and seismic signals from most of the lake floor, indicating total absorption by the methane gas-filled sediment. In the shallow lake margin environments, generally less than 10 m water depth, gas is absent and a detailed stratigraphy of multiple reflectors from tephra layers was observed with sub-bottom profiles. The basin sediments of Lake Rotorua are significantly pockmarked, with deep, circular flat-bottomed depressions c. 20-60 m diameter and 0.5-6 m depth. The pockmarks are located on the lake floor in areas where the sediment is saturated with gas.

To gain an understanding of the transfer of nutrients and trace elements from sediment pore waters to surface waters of eutrophic Lake Rotorua and the early diagenetic processes controlling the transfer, pore water chemistry in the sediments of Lake Rotorua was investigated over a one year period in 2006 by collection of sediment cores on three occasions and deployment of pore water equilibrators on two occasions. Pore water concentrations of Fe2+, Mn2+, S, PO4, NH4, As, Cd, and Pb were analysed. Phosphate and ammonium fluxes to the water column from the sediments were calculated from measured concentration gradients by Fick's law of diffusion. Gas present in the sediments was analysed for composition, and source, and its ebullition rate measured. Anaerobic oxidation of organic matter is indicated by negative Eh values. Sulfate reduction was indicated near the sediment-water interface and releases of Fe2+, Mn2+, PO4 and NH4 into the pore water from particulate material were associated with the reducing conditions. Peaks in concentration of nutrients and elements occurred at the sediment surface over summer and deeper in the pore water profile over the cooler months of May and September. Sampling with peepers at fine scales immediately above the sediment-water interface indicated the presence of a nepheloid layer where elements are actively being recycled. Sulfate reduction appears to occur in the layer above the sediment-water interface, indicating that dissolved oxygen has already been reduced. Phosphorus is possibly being removed by iron and manganese oxide/hydroxide precipitation 5 to 15 cm above the sediment-water interface. Pore water saturation calculations indicate that sulfides may be controlling concentrations of iron and possibly other metals in the pore water by formation of pyrite in the zone of sulfate reduction. Below the zone of sulfate reduction, siderite and vivianite may be precipitating and acting as an additional sink for iron and phosphorus. ii Nutrient release rates based on Fick's law of diffusion indicated 430 tonnes of dissolved phosphorus and 1150 tonnes of ammonium were released to Lake Rotorua's water column in 2006, suggesting nutrient release from the sediments is the dominant flux of nutrients to the water column of Lake Rotorua. Methanogenesis, from acetate fermentation, occurs below the zone of sulfate reduction, where it becomes the dominant process in organic matter degradation. Ebullition of gas was measured at 126 ml m-2 d-1 and this gas was comprised dominantly of methane. Possible remediation techniques that could reduce the internal load of nutrients released from the lake sediments include sediment removal by dredging or capping the sediments with an adsorbent or sealing layer. Capping the sediments could be compromised by ebullition of gas that would disrupt the capped layer, opening up pathways that allow more readily for exchange between pore water nutrients and the water column. Dredging is likely to stimulate the ebullition of most of the trapped gas and result in a rapid efflux of much of the nutrient rich pore water into the lake, however dredging the top 10 to 20 cm of the sediments may partially reduce phosphorus in the pore waters but would not substantially reduce ammonium and fluxes would remain similar to current levels. Improving redox conditions in the sediments could reduce pyrite formation improving phosphorus binding with iron.

A palaeolimnological study was carried out on a high-resolution, 7.62 m-long core (RU188-07) from northern Lake Rotorua, North Island. The core consists predominantly of olive diatomaceous ooze, laminated in places, and contains five tephras including Tarawera (1886 A.D.), Kaharoa (c. 1314 A.D.), Taupo (c. 233 A.D.) and Whakatane (c. 5500 cal. years B.P.). The core terminated in Whakatane Tephra giving the sediment a maximum age of 5530 60 cal. years B.P. An age model for the sediment was developed using tephrochronology. Radiocarbon dates obtained on the sediment returned ages too old because of contamination by old CO2 or CH4, or both. Investigations carried out on the core included spectrophotometric, sedimentological and geochemical analyses, and diatom identifications, which provided a number of proxies from which inferences were made about lake history, catchment development, and palaeoclimate since c. 5500 cal. years B.P. The laminations, evident only in the upper, post-Kaharoa Tephra part of the record, comprise alternations of thin, dark, detrital deposits and pale, relatively fine-grained diatom assemblages. Sediment geochemistry indicates that the Rotorua catchment has undergone several changes since c. 5500 cal. years B.P., alternating between periods of variable and stable environmental conditions. Following the Whakatane and Waimihia eruptions and up to approximately 3000 cal. years B.P., the catchment surrounding Lake Rotorua was rather unstable. Fluctuations in many of the proxies during this period are likely to be associated with a variable climate with periods of storminess, coinciding with the establishment of ENSO conditions in New Zealand. A notable feature of the record is two phases of stability, the first following the Taupo eruption (from c. 1700 cal. years B.P. to c. 630 cal. years B.P.) and the second from c. 580 cal. years B.P. to c. 300 cal. years B.P. The latest, most significant event in the catchment history of Lake Rotorua was the settlement by Polynesians. M.S. McGlone implied from pollen profiles (from Holden's Bay) that initial settlement took place around the time of the Kaharoa eruption (c. 630 cal years B.P.; c. 1314 A.D.), but the sediment chemistry and erosion profiles obtained here, from the northern part of Lake Rotorua, indicate that although there may have been some early clearing in the northern catchment for tracks or buildings, large-scale clearing in the area probably did not occur until considerably later, c. 300 cal. years B.P. Also contained within the sediments are three layers of reworked tephric material that probably originate from the transfer of coarse grained tephra from shallow to deeper water during large storms at c. 1300 cal. years B.P, c. 520 cal. years B.P, and c. 220 cal. years B.P. Each event coincides with storm events inferred from records from Lake Tutira in eastern North Island. Because of Lake Rotorua's inland position, these inferred storm events probably represent only the largest cyclonic events (e.g. ex-tropical cyclones).

Thesis (M.Sc.)--University of Waikato, 2007. / Title from PDF cover (viewed March 18, 2008) Includes bibliographical references.

This thesis presents a new GIS-based scenario volcanic risk assessment model called RiskScape Volcano (RSV) that has been designed for the RiskScape program to advance the field of volcanic risk assessment. RiskScape is a natural hazards risk assessment software tool being developed in New Zealand by GNS Science and NIWA. When integrated into RiskScape, RSV will add proximal volcanic hazard risk assessment capability, and enhanced inventory design; it presently operates outside of RiskScape by combining volcanic hazard models’ output spatial hazard intensity (hazard maps) with inventory databases (asset maps) in GIS software to determine hazard exposure, which is then combined with fragility functions (relationships between hazard intensity and expected damage ratios) to estimate risk. This thesis consists of seven publications, each of which comprises a part of the development and testing of RSV: 1) results of field investigation of impacts to agriculture and infrastructure of the 2006 eruption of Merapi Volcano, Indonesia; 2) agricultural fragility functions for tephra damage in New Zealand based on the observations made at Merapi; 3) examination of wind patterns above the central North Island, New Zealand for better modeling of tephra dispersal with the ASHFALL model; 4) a description of the design, components, background, and an example application of the RSV model; 5) test of RSV via a risk assessment of population, agriculture, and infrastructure in the Rotorua District from a rhyolite eruption at the Okataina Volcanic Centre; 6) test of RSV via a comparison of risk to critical infrastructure in Mammoth Lakes, California from an eruption at Mammoth Mountain volcano versus an eruption from the Inyo craters; and 7) a survey of volcanic hazard awareness in the tourism sector in Mammoth Lakes. Tests of the model have demonstrated that it is capable of providing valid and useful risk assessments that can be used by local government and emergency management to prioritise eruption response planning and risk mitigation efforts. RSV has provided the RiskScape design team with a more complete quantitative volcanic risk assessment model that can be integrated into RiskScape and used in New Zealand and potentially overseas.

This thesis presents a new GIS-based scenario volcanic risk assessment model called RiskScape Volcano (RSV) that has been designed for the RiskScape program to advance the field of volcanic risk assessment. RiskScape is a natural hazards risk assessment software tool being developed in New Zealand by GNS Science and NIWA. When integrated into RiskScape, RSV will add proximal volcanic hazard risk assessment capability, and enhanced inventory design; it presently operates outside of RiskScape by combining volcanic hazard models’ output spatial hazard intensity (hazard maps) with inventory databases (asset maps) in GIS software to determine hazard exposure, which is then combined with fragility functions (relationships between hazard intensity and expected damage ratios) to estimate risk. This thesis consists of seven publications, each of which comprises a part of the development and testing of RSV: 1) results of field investigation of impacts to agriculture and infrastructure of the 2006 eruption of Merapi Volcano, Indonesia; 2) agricultural fragility functions for tephra damage in New Zealand based on the observations made at Merapi; 3) examination of wind patterns above the central North Island, New Zealand for better modeling of tephra dispersal with the ASHFALL model; 4) a description of the design, components, background, and an example application of the RSV model; 5) test of RSV via a risk assessment of population, agriculture, and infrastructure in the Rotorua District from a rhyolite eruption at the Okataina Volcanic Centre; 6) test of RSV via a comparison of risk to critical infrastructure in Mammoth Lakes, California from an eruption at Mammoth Mountain volcano versus an eruption from the Inyo craters; and 7) a survey of volcanic hazard awareness in the tourism sector in Mammoth Lakes. Tests of the model have demonstrated that it is capable of providing valid and useful risk assessments that can be used by local government and emergency management to prioritise eruption response planning and risk mitigation efforts. RSV has provided the RiskScape design team with a more complete quantitative volcanic risk assessment model that can be integrated into RiskScape and used in New Zealand and potentially overseas.

This thesis analyses research into the evolution and adaptation of the communities in Rotorua and Kaikoura by using a complex systems perspective. This perspective requires that the analyst look beyond the obvious impacts of tourism such as employment, crowding, and congestion, to the processes that underlie the experiences of local people in relation to tourism. The configuration of the destination, the flows of people in the area, the visitor types and the ratio of hosts to guests all influence a community's interactions with tourists. In small destinations, the effect of host interactions with guests is potentially much greater than is the case in larger destinations. However, in using a complex systems perspective to analyse the effects of tourism on these two destinations, it becomes clear that the impacts of tourism are more than just the impacts of tourists. The impacts of tourism are intertwined with the processes of trust, leadership and decision making occurring both within the community and within the wider regional and national socio-economic systems. As such, local perceptions of tourism are associated with history, geography, local politics and local social processes. As concepts, the meanings of both 'tourism' and 'community' emerge from the experiences people have, and the associations that they make with the two terms. Thus, the meaning of both 'tourism' and 'community' are idiosyncratic and locally defined. Each term means different things to residents in Rotorua and Kaikoura, and each affects how residents perceive tourism in their respective towns. For example, the associations that people make between historical events and processes such as restructuring are quite different in each of the two communities. In Rotorua, tourism is seen as a source of stability, as a phenomenon that confers a higher level of perceived control on the community. In Kaikoura, tourism is seen as a source of change and it confers a lesser sense of perceived control on the community overall. Likewise, the relationship between the local council and the community underlies the sense of security people feel about local decision making processes. This relationship is mediated by a range of processes including the effort that the council put into communicating with community members, the leadership shown by the council, the way in which they facilitate community visioning processes, which then provide a basis for both leadership and decision making. Underlying these processes are community processes of rivalry, competition, cooperation, labelling and stereotyping that all affect the levels of trust that the community have in those around them. Community cohesion (which is not the same as community agreement) underlies a community's ability to work together to manage tourism. Thus using a complex systems approach to analyse the impacts of tourism in two destinations has shown that there is much more to tourism than the impacts of tourists and their activities. Instead, the way the community system interacts with the tourism system gives rise to the impacts of tourism. Tourism can be usefully conceptualised as a process that is inextricably interwoven with history, politics and community interaction processes at the destination level. Perceptions of tourism reflect these processes and the understanding that local people have of them, and the level of control that they feel they have over tourism development. With little trust in local decision making processes, people have a low sense of control over how tourism development affects them. In tourism planning, therefore, it may be more effective to focus primarily on the processes by which tourism development and management occurs in the local area and to look at mitigating the effects of tourists only after building community capacity to adaptively manage tourism in their area. Communities need a sense of control over their world, and this is only undermined when experts and institutions try to advise courses of action without involving a range of community players in the process of managing tourism. Thus, government and other organisations and institutions at local level must focus on working with communities to build local capacity to manage tourism, without imposing on those communities to convince them to 'treat tourists well' or to manage their environment better, so they become more attractive as a destination.

This study was concerned with the health implications of new forms of gambling such as casinos, pokie machines and internet gambling for Māori women and their families in Auckland and the Bay of Plenty region of Aotearoa (New Zealand). It set out to discover what culturally appropriate services were available and the extent to which Māori women gamblers were utilising them. The literature documenting Māori perceptions of gambling shows that Māori women gamblers and their partner/whānau members and gambling service providers have been little studied previously. These goals translated into the following specific aims: 1) to study how Māori women problem gamblers, their partner or whānau members and key informants perceived gambling, what it meant to them and why they did it; 2) to investigate the consequences of gambling for Māori women, whānau and service providers in dealing with the effects of gambling; 3) to report on how these three groups dealt with the effects of gambling; and 4) to discover what helped to bring about positive changes for the three groups. All of the aims were achieved. A Māori approach (Kaupapa Māori), combined with a naturalistic approach to data collection, was adopted. Qualitative methods are most appropriate to use when working with some Māori, as there is a growing realisation that research with Māori needs to be interactive. A Māori research procedure modelled on the ritual ceremony of encounter (Pōwhiri) provided an appropriate structure for the development and presentation of the research process. The major focus was on the qualitative data obtained from semi-structured interviews in two locations - Rotorua and Auckland. The interviews were conducted with twenty Māori women gamblers, sixteen whānau members including partners and ten interviews with staff involved in services that provided help for problem gamblers. The three interview schedules were based on a number of broad themes and open-ended questions to obtain meaningful descriptive data. The interviews were audio recorded and used to produce transcripts that were then sent back to the participants for feedback. Qualitative data analysis was conducted on the returned documents. The findings from this study revealed major impacts of the women's socio-economic, familial and societal circumstances on gambling behaviour and its effects, which are areas of concern for mental health professionals and researchers. The mythical Māori canoes on which Māori voyaged from their place of origin (Hawaiiki) to Aotearoa, the Waka, provided an appropriate metaphor to present the interrelationship between the pull and push factors toward gambling, and its implications for society. This is illustrated as a spinning waka, Te Waka Hūrihuri. On the other hand, Te Waka Māia (courageous) demonstrates the relationships between the variables that help Māori women gamblers to cope and helpful strategies found to assist them to modify or stop their gambling behaviour. It is recommended that the government limit the proliferation of gaming venues and continue to encourage development of emerging Māori services. Moreover, a coordinated approach is essential, as Māori women gamblers, partners and whānau members need to heal together for positive outcomes for Māori health development in Aotearoa. The main implication of this study is that a wide range of further research into Māori and gambling is required. Recommendations on ways in which the current delivery of services in Rotorua and Auckland could be improved are: That the Ministry of Health purchase services that establish support groups for Māori people with problem gambling and their whānau, and That non-Māori provider services and organisations support the development of emerging Māori services. Heeding the outcome of this research should help improve New Zealand's existing health policy and capacity for Māori women's health development. It should also enrich our understanding of the adaptation patterns of Māori whānau member/s, and thus should have implications, not only for Māori health policies, but also relevance for the wider field of international cross-comparative research on indigenous gambling and mental health issues. Limitations of this study included a small, localised sample that means the findings can only tentatively be generalised to the wider population of Māori women gamblers. Nonetheless, information gained from the study contributes to understanding of the adaptation patterns of Māori women gamblers, their whānau member/s, and those who are trying to help them. It is hoped that the study will make it at least a little less true that every day is a war day for Māori women and their whānau trying to deal with the problem of gambling.