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Satellite earth observation data has become fundamental in efforts to map coastal change at large geographic scales. Research has generally focussed on extracting the instantaneous waterline position from time-series of satellite images to interpret long-term trends. The use of this proxy can, however, be uncertain because the waterline is sensitive to marine conditions and beach gradient. In addition, the technique disregards potentially useful data stored in surrounding pixels. In this paper, we describe a pixel-based technique to analyse coastal change. A hybrid rule-based and machine learning methodology was developed using a combination of Sentinel multispectral and Synthetic Aperture Radar composite imagery. The approach was then used to provide the first national-scale pixel-based landcover classification for the open coast of New Zealand. Nine landcover types were identified including vegetation, rock, and sedimentary classes that are common on beaches (dark sand, light sand, and gravel). Accuracy was assessed at national scale (overall accuracy: 86%) and was greater than 90% when normalised for class area. Using a combination of optical and Synthetic Aperture Radar data improved overall accuracy by 14% and enhanced the separation of coastal sedimentary classes. Comparison against a previous classification approach of sandy coasts indicated improvements of 30% in accuracy. The outputs and code are freely available and open-source providing a new framework for per-pixel coastal landcover mapping for all regions where public earth observation data is available. [ABSTRACT FROM AUTHOR]

The endemic bull kelp Durvillaea willana Lindauer grows on South and Stewart/Rakiura Islands, with a small North Island population on the northern Wairarapa coast. Drawing on field observations, the distribution of this species is mapped. Within its biogeographic range, there are three lengthy tracts of rocky shore where the kelp is conspicuously absent. These distributional gaps are: Wellington's south coast (despite proximity to populations on the South Island side of Cook Strait), the southern and central Wairarapa Coast, and in South Westland. Theorising that these gaps have been caused by earthquake-driven coastal uplift, this paper examines the effects on Durvillaea species of a 7.8 Mw earthquake in 2016, which raised around 100 km of seashore along the Kaikōura coast, plus the historical evidence of uplift along the Akatore Fault, south of Dunedin. This evidence suggests that the requirements for such local extinctions are that the uplift is consistently higher than the kelp's vertical range, and that it occurs along an entire rocky coastal tract flanked by barriers to recolonisation such as long beaches or deep ocean–major obstacles to a non-buoyant kelp with poor dispersive ability. [ABSTRACT FROM AUTHOR]

Mead, S.T. and Atkin, E.A., 2019. Managing issues at Aotearoa New Zealand's surf breaks. In: Bryan, K.R. and Atkin, E.A. (eds.), Surf Break Management in Aotearoa New Zealand. Journal of Coastal Research, Special Issue No. 87, pp. 13–22. Coconut Creek (Florida), ISSN 0749-0208. Policy 16 of the New Zealand Coastal Policy Statement 2010 (NZCPS) provides a legislative framework that identifies and calls for the protection of surf breaks of national and regional significance by "ensuring that activities in the coastal environment do not adversely affect the surf breaks" and by "avoiding adverse effects of other activities on access to, and use and enjoyment of the surf breaks". While this is ground-breaking as the world's first environmental policy to specifically identify surf breaks as protected spaces, it has been somewhat toothless in its effectiveness because there are no clear, quantitative measures or guidelines describing the oceanographic or geomorphic characteristics of the coastal zone that contribute to the functionality of a surf break. This paper summarises our existing knowledge concerning surf breaks in New Zealand and highlights the management issues facing local communities and councils; it presents an example of an implemented management approach and the way forward with the recently completed national management guidelines for surfing resources, which are a world first. [ABSTRACT FROM AUTHOR]

ABSTRACT Kench, P.S.; Ryan, E.J.; Owen, S.; Bell, R.; Lawrence, J.; Glavovic, B.; Blackett, P.; Becker, J.; Schneider, P.; Allis, M.; Dickson, M., and Rennie, H.G. 2018. Co-creating resilience solutions to coastal hazards through an interdisciplinary research project in New Zealand, In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1496–1500. Coconut Creek (Florida), ISSN 0749-0208. Coastal communities ‘living at the edge’ face intensification and acceleration of coastal hazard risk in the face of climate change. Communities will need to be adaptive in reducing these risks now and over long timeframes. Developing coastal hazard adaptation pathways requires co-production of interdisciplinary knowledge between scientists, policy makers and communities. However, there remains little guidance and limited dialogue about the research practices and frameworks that underpin co-created research. In a first for New Zealand, a co-created research programme is underway titled ‘Living at the Edge’ that aims to improve the resilience of coastal communities to coastal hazards. This paper provides novel insights into the complexities underpinning the formative stages of co-created research, drawing on practical experience from the Living at the Edge project. We explore the enablers and shapers that led to co-created shifts in the research project objectives and framework. Notions of integration, trust, and flexibility are three fundamental aspects that influenced the early stages of co-creation. The importance of bridging interactions with actors early on in co-created projects is exemplified. [ABSTRACT FROM AUTHOR]

Anticipating and managing the impacts of sea‐level rise for nations astride active tectonic margins requires understanding of rates of sea surface elevation change in relation to coastal land elevation. Vertical land motion (VLM) can either exacerbate or reduce sea‐level changes with impacts varying significantly along a coastline. Determining rate, pattern, and variability of VLM near coasts leads to a direct improvement of location‐specific relative sea level (RSL) estimates for coastal hazard risk assessment. Here, we utilize vertical velocity field from interferometric synthetic aperture radar (InSAR) data, calibrated with campaign and continuous Global Navigation Satellite System data, to determine the VLM for the entire coastline of New Zealand. Guided by available knowledge of the seismic cycle, the VLM data infer secular, interseismic rates of land surface deformation. Using the Framework for Assessing Changes to Sea‐level (FACTS), we build probabilistic RSL projections using the same emissions scenarios employed in IPCC Assessment Report 6 and local VLM data at 8,179 sites, thereby enhancing spatial coverage that was previously limited to four tide gauges. We present ensembles of probability distributions of RSL for each scenario to 2150, and for low confidence sea‐level processes to 2300. Where land subsidence is occurring at rates >2 mm/y VLM makes a significant contribution to RSL projections for all scenarios out to 2150. Our approach can be applied to similar locations across the world and has significant implications for adaptation planning, as timing of threshold exceedance for coastal inundation can be brought forward (or delayed) by decades. Plain Language Summary: This study outlines an approach for deriving probabilistic projections of relative sea‐level change that account for changes in land surface elevation continuously along a coastline. Previous sea‐level projections that included vertical land movements (VLMs) were restricted to tide gauge locations. To provide spatial‐resolution required by practitioners for effective adaptation planning, we have combined elevations measured using satellite radar data with measurements from land‐based Global Navigation Satellite System (GNSS) receivers to build a continuous VLM database showing land uplift and subsidence (sinking) for the entire coastline of New Zealand. We integrate these data into probabilistic sea‐level projection methodology used in Intergovernmental Panel on Climate Change (IPCC) Assessment Report 6 (AR6) for the range of future climate scenarios. Our approach could be applied to any region of the world where the coastline is affected by VLM due to secular tectonic deformation. Downward land movement >2 mm/y makes a significant contribution in sea‐level projections for all climate scenarios out to the end of this century. This means that adaptation planning decision thresholds, such as those linked to the impacts of coastal flooding and inundation, may be brought forward by decades. Key Points: Anticipating impacts of sea‐level rise for active tectonic margins requires location‐specific knowledge of vertical land movement (VLM)VLM from geodetic measurements integrated with IPCC AR6 projections to provide probabilistic RSL estimates for dynamic coastlinesDownward VLM > 2 mm/y makes a significant contribution to RSL projections bringing forward adaptation decision thresholds by decades [ABSTRACT FROM AUTHOR]

The New Zealand coastline faces the risk of tsunami from a variety of sources, including remote and local earthquakes, submarine landslides, and volcanoes. Palaeotsunami studies indicate New Zealand has undergone periods of catastrophic tsunami activity, such as in the 1500s. It is important to be able to quantify the hazard posed by tsunamis. In this paper we detail the process of modelling tsunami propagation and inundation from source to destination using RiCOM, a finite element coastal hydrodynamic model on an unstructured grid. We give examples of model outputs, such as maps of tsunami inundation depth, maximum speeds, wave arrival times and time spent inundated, which can be used to quantify the hazard. We also perform sensitivity analysis of the response of the tsunami to the average slip on, and length and width of, the fault surface while keeping the moment magnitude and all other parameters constant. Larger average slip is shown to produce larger tsunamis. The width/aspect ratio of the slip has a more variable effect on the size of the tsunami, which depends upon the local coastal geometry. This information can be used to identify risk areas, plan escape routes, protect people and infrastructure and, more generally, to inform the public as to the tsunami risk in their region. [ABSTRACT FROM AUTHOR]

The New Zealand sea sand ore is a kind of vanadia–titania magnetite formed by erosion in the coastal zone. Because of its coarse particle size, smooth spherical particles, complex chemical composition, it has been added to sinter as an auxiliary material. Based on the principle of optimizing ore blending to strengthen advantages and weaken disadvantages, this paper used New Zealand sea sand raw ore that has not undergone any pretreatment as the main material and prepared it into oxidized pellets using a disc pelletizer and explored the influence of high-proportion unground sea sand ore on the preparation process and reduction performance of oxidized pellets. The influence of unground sea sand ore on the falling strength, compressive strength, reduction swelling index, and reduction degree of pellets was analyzed by the ICPAES, XRF, XRD, SEM-EDS, and other detection methods, and the change laws and influencing factors of oxidized pellets were analyzed. With the increase of the amount of unground sea sand ore used, the falling strength and compressive strength of the green pellets first decreased and then gradually increased, while the compressive strength of the oxidized pellets first increased and then decreased. At the same time, as the amount of sea sand ore used increased, the reduction process of pellets was restricted. The reduction swelling index and the reduction degree index generally show a downward trend. However, the compressive strength of the pellets gradually increased after reduction. Through the research on the pellet-forming performance and reduction properties of unground sea sand ore, it is shown that when the amount of unground sea sand ore used was 40%, it can still be used as raw material for blast furnace ironmaking. Thus, this research provided specific data support for iron and steel enterprises to improve the ratio of unground sea sand ore and reduce production cost. [ABSTRACT FROM AUTHOR]

Dunelands are one of the most dynamic environments on Earth, which greatly hinders their conservation and management. In the dune slacks along the Manawatū coast, New Zealand, lies a zone of small, temporary, freshwater wetlands that host early seral communities of rare turf plants. Analysis of historical aerial photos allowed determination of coastline movement, distance of the wetlands from the coast, and wetland movements through time. Study sites were around the coastal settlements of Tangimoana and Foxton Beach, both having major rivers debouching nearby, and Himatangi, amongst stabilising exotic pine plantations. The coastline is prograding (with seaward movement) generally by 0.7–1 m yr−1, but is more variable closer to river mouths, with episodes of movement of up to 15 m yr−1. Wetlands occur 200–400 m behind the strandline, are closer to the coast at Foxton Beach, and furthest away at Himatangi. Wetlands wobble in their position at 5.2 m yr−1 but migrate inland at an average of 2.7 m yr−1. Wetland size appears unrelated to rainfall, but may be related positively to coastal progradation rate, to which wetland movement is negatively related. Near the major rivers, dunes are less stable, and wetlands can be impacted both positively and negatively. Wetland existence and movement is balanced between stability and dynamism on the coast, and management will need to be proactive to maintain environments for early successional turfs. [ABSTRACT FROM AUTHOR]

Coastal flooding is a major global hazard, yet few studies have examined the spatial and temporal characteristics of extreme sea level and associated coastal flooding. Here we analyse sea-level records around the coast of New Zealand (NZ) to quantify extreme storm-tide and skew-surge frequency and magnitude. We identify the relative magnitude of sea-level components contributing to 85 extreme sea level and 135 extreme skew-surge events recorded in NZ since 1900. We then examine the spatial and temporal clustering of these extreme storm-tide and skew-surge events and identify typical storm tracks and weather types associated with the spatial clusters of extreme events. We find that most extreme storm tides were driven by moderate skew surges combined with high perigean spring tides. The spring–neap tidal cycle, coupled with a moderate surge climatology, prevents successive extreme storm-tide events from happening within 4–10 d of each other, and generally there are at least 10 d between extreme storm-tide events. This is similar to findings from the UK (Haigh et al., 2016), despite NZ having smaller tides. Extreme events more commonly impacted the east coast of the North Island of NZ during blocking weather types, and the South Island and west coast of the North Island during trough weather types. The seasonal distribution of both extreme storm-tide and skew-surge events closely follows the seasonal pattern of mean sea-level anomaly (MSLA) – MSLA was positive in 92 % of all extreme storm-tide events and in 88 % of all extreme skew-surge events. The strong influence of low-amplitude (-0.06 to 0.28 m) MSLA on the timing of extreme events shows that mean sea-level rise (SLR) of similarly small height will drive rapid increases in the frequency of presently rare extreme sea levels. These findings have important implications for flood management, emergency response and the insurance sector, because impacts and losses may be correlated in space and time. [ABSTRACT FROM AUTHOR]

Hart, D.E., 2007. River mouth lagoon dynamics on mixed sand and gravel barrier coasts. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 927 – 931. Gold Coast, Australia, ISSN 0749.0208 This paper examines the dynamics of river-mouth lagoons on mixed sand and gravel coasts receiving high wave energy. The role played by rivers in these non-estuarine systems is recognised as essential for carving out space for the coast-parallel waterbody, defining its physical scale, and for driving cycles of lagoon behaviour from closure to breaching. The role played by waves, by contrast, is not fully recognised in that it is limited to barrier building across river mouths and gradual lagoon-outlet offsetting along the shore. Field observations and water-level records were used in combination with river-flow, wave, and hourly-camera records at the Ashburton river mouth, New Zealand, to establish the importance of wave versus river forcings of lagoon dynamics. Several new behaviours were identified, including storm-induced lagoon breaching, rapid longshore migrations in outlet position and outlet channel truncations in response to storm-wave overtopping. Similar dynamics forced by combined river-flood and storm events were also common. Despite the observed complexity of river, wave and lagoon processes, characteristic morphologies and equilibrium states were apparent, with the lagoon appearing to be dominated by wave processes at all but the highest river-flow stages. Analysis of the frequency of the observed events is used as the basis of a new understanding of lagoon behaviour, from which management implications are drawn. [ABSTRACT FROM AUTHOR]

The yellow-green algae Vaucheria velutina and Vaucheria longicaulis are identified using morphological characters of fertile material from the eastern coastline of Auckland. The former species occurs in extensive low intertidal beds on sheltered, muddy shores. The latter species was found in Orakei Basin, and is a new record for New Zealand. [ABSTRACT FROM AUTHOR]

The article offers information on the study that focuses on late summer hyperbenthic estuarine communities, comparing permanently open and intermittently closed systems along the Otago coastline in New Zealand. It outlines the method employed in the study, and highlights the results of the study with respect to physical and chemical variation, community structure, and open versus intermittently closed estuaries.

Barrier islands in sheltered settings are rare coastal geomorphic features. Here we present a case study of controls on the evolution of Tapora Island, North Island, New Zealand. Tapora Island is an active barrier island located opposite the entrance to the Kaipara Harbour on a high-energy coast. Subsurface facies form an aggradational barrier island succession from subtidal to subaerial elevations. This facies succession, combined with surface samples and geomorphic and geologic relationships, indicates that Tapora Island is the most recent barrier island at this location in the estuary and forms part of a prograded coast opposite the entrance. Wave data indicate that ocean swell waves penetrate the inlet for approximately 2 hours either side of high tide and are capable of transporting sand onto the island. The combined effects of swell waves, abundant sediment supply, and exposed aspect are the critical factors that have formed the barrier island. Despite the ''sheltered' estuarine setting, Tapora Island has formed under conditions that are more akin to open ocean coasts. The origin and development of Tapora Island broadly conforms to the accumulating barrier island model. [ABSTRACT FROM AUTHOR]

The magnitude 9.5 earthquake on 22 May 1960 in southern Chile was the largest instrumentally recorded earthquake in the 20th century. It generated a tsunami that swept the shores of Chile and radiated out across the Pacific, with the major loss of life in Chile and, despite warnings being issued, in both Hawai'i and Japan. The absence of a Pacific-wide tsunami warning system at the time meant that the tsunami struck New Zealand without an official warning being issued. Fortunately, there was no loss of life despite widespread damage to coastal facilities. A large aftershock occurred in Chile 3 days later (25 may) and fears about a tsunami from this event resulted in the broadcasting of a nationwide warning on radio in New Zealand. Newspapers of the day reported that thousands of people around the country were evacuated, making this the largest and most widespread evacuation in New Zealand's history. Almost the entire population of Whitianga, Waihi Beach, Whakatane, Ohope, and Opotiki were moved to high ground for several hours and, in many other communities, people self-evacuated from coastal fringes. After the event, there was much discussion in the newspapers of the need to improve both warnings and public awareness of the hazard, and of the appropriate response to warnings. Over the 40 years from 1960 up to the 26 December 2004 Indian ocean tsunami, public awareness of New Zealand's tsunami risk and preparedness had waned. Since 2004, the renewed focus on tsunami has built on a range of improvements in emergency management policies and practices, and the lessons identified from the event paved the way for a number of new initiatives to get underway to enhance the New Zealand's tsunami warning capacity and capability. [ABSTRACT FROM AUTHOR]

Mesoscale lows are observed off the central west coast, South Island, New Zealand. These features are evidenced in pressure dips measured at a buoy moored about 50 km off the west coast. They do not appear in measurements from coastal stations. Wind data at the buoy show complex variations sometimes consistent with the passage of cyclonic vortices in the flow. Further, wind data from satellite scatterometers often indicate high spatial variability near the buoy at the time of these pressure dips, and satellite imagery depicts cloud movements consistent with small-scale cyclonic circulations near the coast. These features are often observed in the cool air after the passage of a trough or front. [ABSTRACT FROM AUTHOR]