title: Monitoring the Coastal Sand Wedge Outbreak from the Stony River, Taranaki

authors: Cowie, Nicola Anne

subjects: Taranaki

abstract: The Taranaki headland protrudes into a high energy wave climate system with a potential for strong littoral transport.  This shoreline is typically comprised of a narrow cobble to boulder reflective beach, surmounting a rugged wave cut shore platform which is carved into lahar deposits from the nearby andesitic composite cone of Mount Taranaki.  Historically along this coast, pocket sandy beaches have endured within embayments and adjacent to headland features; otherwise the the Taranaki littoral system is sand-starved.  In 1998, persistent heavy rainfall resulted in the collapse of scoriaceous sand and gravel on the side of Mount Taranaki, leading to massive injection of sand and gravel directly into the Stony River, from which the adjacent coastal shoreline has experienced a continuous flux of dense 'black' titanomagnetite-rich volcanic sands.  These sediments are rapidly transported to the north-east by the energetic wave climate, creating sandy beaches on what is normally a rocky boulder coast.
Coastline changes between Cape Egmont and New Plymouth were analysed by the comparison of aerial photographs dated 1995, 2001, and 2007.  These photos illustrated a marked increase in sandy sediment in 2001 which has diminished rapidly by 2007.  Sub-aerial beach profiles were undertaken, over the duration of this study, at 12 locations between Komene Road, just south of the Stony River mouth, and Back Beach in New Plymouth.  The beaches including and south of Ahuahu Beach are characterised by dunes which reach greater elevations than those further north where the dune elevation decreases.  This evidence along with visual observations suggest that the sediment derived from the Stony River sits on the upper beach forming a berm and high dunes.
Sediment textural analysis was conducted on samples collected at the 12 beach profiling locations.  This analysis was undertaken every three months over the course of this study  and showed (1) a decrease in mean grain size with distance north of the Stony River mouth; and (2) sorting generally improves with distance north-east in the direction of the dominant littoral drift.  Mineralogical analysis illustrated that beach sediments are dominated by the heavy mineral titanomagnetite and the opaque minerals of augite, hornblende and plagioclase feldspar.
The longshore sediment transport flux between Rahotu Road, south of Cape Egmont) and Back Beach in New Plymouth was examined.  Wave climate parameters were generated at 55 locations between 1998 and 2007 using the SWAN third generation numerical model.  The CERC (1973) formula was used to calculate the potential longshore sediment transport flux, at each of these locations using the significant wave height and angle of incidence. Analysis of the wave data illustrate a wave energy gradient extends from the Cape toward New Plymouth, caused by: (1) the exposed nature of the coast near Cape Egmont to the dominant south-westerly swells; (2) the greater seabed gradient near Cape Egmont, and (3) the refraction shadowing that occurs with distance to the northeast of the Cape.  The potential longshore sediment transport results indicate low potential sediment transport fluxes south of Cape Egmont, which increase, reaching a maximum potential flux slightly south of the Stony River mouth.  These potential longshore sediment transport fluxes then decrease towards Back Beach as a result of refraction in the vicinity of the Sugar Loaf Islands.  The size of the 'slug' of sand derived from the headwaters of the Stony River is likely to have diminished in size substantially when it has been transported as far north as Back Beach, and these results indicate that there will be insufficient energy for any substantial volumes to be transported around the Paritutu Headland.
A sediment budget has been ascertained from the volume of sediment that has recently been eroded from the scarp on Little Pyramid on Mount Taranaki, and the volume of sediment that can be accounted for today on the beaches, and in the Stony River channel as aggradation deposits.  Up to 14.4 M m3 of sediment was estimated to have been deposited in the Stony River system directly from the scarp.  Of this, ~ 3.5 M m3 has accumulated on the sub-aerial beach over a distance of 14 km to east from just south of the river mouth, and ~3.3 M m3 has been deposited along the Stony River channel.  The remaining ~7.6M m3 of sediment is likely to be deposited offshore, overlying the wave-swept boulder platform and in the interstitial space of the sediments that form these shore platforms.  Significant quantities of this sediment are also likely to have been transported in the north-east directed littoral transport.

text: Monitoring the Coastal Sand Wedge Outbreak from the Stony River, Taranaki The Taranaki headland protrudes into a high energy wave climate system with a potential for strong littoral transport.  This shoreline is typically comprised of a narrow cobble to boulder reflective beach, surmounting a rugged wave cut shore platform which is carved into lahar deposits from the nearby andesitic composite cone of Mount Taranaki.  Historically along this coast, pocket sandy beaches have endured within embayments and adjacent to headland features; otherwise the the Taranaki littoral system is sand-starved.  In 1998, persistent heavy rainfall resulted in the collapse of scoriaceous sand and gravel on the side of Mount Taranaki, leading to massive injection of sand and gravel directly into the Stony River, from which the adjacent coastal shoreline has experienced a continuous flux of dense 'black' titanomagnetite-rich volcanic sands.  These sediments are rapidly transported to the north-east by the energetic wave climate, creating sandy beaches on what is normally a rocky boulder coast.
Coastline changes between Cape Egmont and New Plymouth were analysed by the comparison of aerial photographs dated 1995, 2001, and 2007.  These photos illustrated a marked increase in sandy sediment in 2001 which has diminished rapidly by 2007.  Sub-aerial beach profiles were undertaken, over the duration of this study, at 12 locations between Komene Road, just south of the Stony River mouth, and Back Beach in New Plymouth.  The beaches including and south of Ahuahu Beach are characterised by dunes which reach greater elevations than those further north where the dune elevation decreases.  This evidence along with visual observations suggest that the sediment derived from the Stony River sits on the upper beach forming a berm and high dunes.
Sediment textural analysis was conducted on samples collected at the 12 beach profiling locations.  This analysis was undertaken every three months over the course of this study  and showed (1) a decrease in mean grain size with distance north of the Stony River mouth; and (2) sorting generally improves with distance north-east in the direction of the dominant littoral drift.  Mineralogical analysis illustrated that beach sediments are dominated by the heavy mineral titanomagnetite and the opaque minerals of augite, hornblende and plagioclase feldspar.
The longshore sediment transport flux between Rahotu Road, south of Cape Egmont) and Back Beach in New Plymouth was examined.  Wave climate parameters were generated at 55 locations between 1998 and 2007 using the SWAN third generation numerical model.  The CERC (1973) formula was used to calculate the potential longshore sediment transport flux, at each of these locations using the significant wave height and angle of incidence. Analysis of the wave data illustrate a wave energy gradient extends from the Cape toward New Plymouth, caused by: (1) the exposed nature of the coast near Cape Egmont to the dominant south-westerly swells; (2) the greater seabed gradient near Cape Egmont, and (3) the refraction shadowing that occurs with distance to the northeast of the Cape.  The potential longshore sediment transport results indicate low potential sediment transport fluxes south of Cape Egmont, which increase, reaching a maximum potential flux slightly south of the Stony River mouth.  These potential longshore sediment transport fluxes then decrease towards Back Beach as a result of refraction in the vicinity of the Sugar Loaf Islands.  The size of the 'slug' of sand derived from the headwaters of the Stony River is likely to have diminished in size substantially when it has been transported as far north as Back Beach, and these results indicate that there will be insufficient energy for any substantial volumes to be transported around the Paritutu Headland.
A sediment budget has been ascertained from the volume of sediment that has recently been eroded from the scarp on Little Pyramid on Mount Taranaki, and the volume of sediment that can be accounted for today on the beaches, and in the Stony River channel as aggradation deposits.  Up to 14.4 M m3 of sediment was estimated to have been deposited in the Stony River system directly from the scarp.  Of this, ~ 3.5 M m3 has accumulated on the sub-aerial beach over a distance of 14 km to east from just south of the river mouth, and ~3.3 M m3 has been deposited along the Stony River channel.  The remaining ~7.6M m3 of sediment is likely to be deposited offshore, overlying the wave-swept boulder platform and in the interstitial space of the sediments that form these shore platforms.  Significant quantities of this sediment are also likely to have been transported in the north-east directed littoral transport.

year: 2009

title: Bringing nature back into cities: urban land environments, indigenous cover and urban restoration

authors: Clarkson, Bruce D.

subjects: New Zealand

abstract: 1. The restoration of urban ecosystems is an increasingly important strategy to maintain and enhance indigenous biodiversity as well as reconnecting people to the environment. High levels of endemism, the sensitivity of species that have evolved without humans, and the invasion of exotic species have all contributed to severe depletion of indigenous biodiversity in New Zealand. In this work, we analysed national patterns of urban biodiversity in New Zealand and the contribution that urban restoration can make to maximising and enhancing indigenous biodiversity. 
2. We analysed data from two national databases in relation to the 20 largest New Zealand cities. We quantified existing indigenous biodiversity within cities, both within the core built up matrix and in centroid buffer zones of 5, 10 and 20 km around this urban centre. We analysed the type and frequency of land environments underlying cities as indicators of the range of native ecosystems that are (or can potentially be) represented within the broader environmental profile of New Zealand. We identified acutely threatened land environments that are represented within urban and periurban areas and the potential role of cities in enhancing biodiversity from these land environments. 
3. New Zealand cities are highly variable in both landform and level of indigenous resource. Thirteen of 20 major land environments in New Zealand are represented in cities, and nearly three-quarters of all acutely threatened land environments are represented within 20 km of city cores nationally. Indigenous land cover is low within urban cores, with less than 2% on average remaining, and fragmentation is high. However, indigenous cover increases to more than 10% on average in the periurban zone, and the size of indigenous remnants also increases. The number of remaining indigenous landcover types also increases from only 5 types within the urban centre, to 14 types within 20 km of the inner urban cores. 
4. In New Zealand, ecosystem restoration alone is not enough to prevent biodiversity loss from urban environments, with remnant indigenous cover in the urban core too small (and currently too degraded) to support biodiversity long-term. For some cities, indigenous cover in the periurban zone is also extremely low. This has significant ramifications for the threatened lowland and coastal environments that are most commonly represented in cities. Reconstruction of ecosystems is required to achieve a target of 10% indigenous cover in cities: the addition of land to land banks for this purpose is crucial. Future planning that protects indigenous remnants within the periurban zone is critical to the survival of many species within urban areas, mitigating the homogenisation and depletion of indigenous flora and fauna typical of urbanisation. A national urban biodiversity plan would help city councils address biodiversity issues beyond a local and regional focus, while encouraging predominantly local solutions to restoration challenges, based on the highly variable land environments, ecosystems and patch connectivity present within different urban areas.

text: Bringing nature back into cities: urban land environments, indigenous cover and urban restoration 1. The restoration of urban ecosystems is an increasingly important strategy to maintain and enhance indigenous biodiversity as well as reconnecting people to the environment. High levels of endemism, the sensitivity of species that have evolved without humans, and the invasion of exotic species have all contributed to severe depletion of indigenous biodiversity in New Zealand. In this work, we analysed national patterns of urban biodiversity in New Zealand and the contribution that urban restoration can make to maximising and enhancing indigenous biodiversity. 
2. We analysed data from two national databases in relation to the 20 largest New Zealand cities. We quantified existing indigenous biodiversity within cities, both within the core built up matrix and in centroid buffer zones of 5, 10 and 20 km around this urban centre. We analysed the type and frequency of land environments underlying cities as indicators of the range of native ecosystems that are (or can potentially be) represented within the broader environmental profile of New Zealand. We identified acutely threatened land environments that are represented within urban and periurban areas and the potential role of cities in enhancing biodiversity from these land environments. 
3. New Zealand cities are highly variable in both landform and level of indigenous resource. Thirteen of 20 major land environments in New Zealand are represented in cities, and nearly three-quarters of all acutely threatened land environments are represented within 20 km of city cores nationally. Indigenous land cover is low within urban cores, with less than 2% on average remaining, and fragmentation is high. However, indigenous cover increases to more than 10% on average in the periurban zone, and the size of indigenous remnants also increases. The number of remaining indigenous landcover types also increases from only 5 types within the urban centre, to 14 types within 20 km of the inner urban cores. 
4. In New Zealand, ecosystem restoration alone is not enough to prevent biodiversity loss from urban environments, with remnant indigenous cover in the urban core too small (and currently too degraded) to support biodiversity long-term. For some cities, indigenous cover in the periurban zone is also extremely low. This has significant ramifications for the threatened lowland and coastal environments that are most commonly represented in cities. Reconstruction of ecosystems is required to achieve a target of 10% indigenous cover in cities: the addition of land to land banks for this purpose is crucial. Future planning that protects indigenous remnants within the periurban zone is critical to the survival of many species within urban areas, mitigating the homogenisation and depletion of indigenous flora and fauna typical of urbanisation. A national urban biodiversity plan would help city councils address biodiversity issues beyond a local and regional focus, while encouraging predominantly local solutions to restoration challenges, based on the highly variable land environments, ecosystems and patch connectivity present within different urban areas.

year: 2007

title: Ka ora | Ka mate

authors: Apiata, Hāwea

abstract: Ekphrasis in response to the artwork 'Matariki' by Hariata Ropata-Tangahoe (Ngāti Toa, Ngāti Raukawa, Te Āti Awa). Written for the One Hundred Years exhibition held at RAMP Gallery, in celebration of the establishment of the first iteration of the technical college a century earlier in 1924. Alumni of the art program were invited to contribute works to the show and local writers were asked to respond to the art, with their works being published in the exhibition catalogue.

text: Ka ora | Ka mate Ekphrasis in response to the artwork 'Matariki' by Hariata Ropata-Tangahoe (Ngāti Toa, Ngāti Raukawa, Te Āti Awa). Written for the One Hundred Years exhibition held at RAMP Gallery, in celebration of the establishment of the first iteration of the technical college a century earlier in 1924. Alumni of the art program were invited to contribute works to the show and local writers were asked to respond to the art, with their works being published in the exhibition catalogue.

year: 2024-02-29