title: The Impact of Dredging on the Stability of Matakana Banks Ebb-Tidal Delta

authors: Ramli, Andi Yulianti

subjects: Ebb Tidal Delat

abstract: The Matakana Banks ebb-tidal delta is located offshore from the Tauranga Entrance to Tauranga Harbour, Bay of Plenty New Zealand. In order to access the Port of Tauranga, Matakana Banks has been dredged to provide a shipping channel with sufficient depth for navigational purposes. In 1968 the first capital-dredging programme included an Entrance Channel through the delta, which was further enlarged in 1992. A biennial maintenance dredging programme has been required to deal with subsequent infilling of the Channel.
Recently, the Port has obtained resource consent to further widen and deepen the Entrance Channel. However, while granting the consent, the Environment Court accepted that dredging could result in adverse impacts to the stability of Matakana Banks and the adjacent Panepane Point on the western side of the tidal inlet. Therefore, this study was undertaken to assess the response of the ebb tidal delta to dredging, and determine possible mitigation measures if dredging has adverse effects.
The study analysed bathymetric data from single beam echo sounder (SBES) surveys obtained from 1998 to 2011. These data indicate that the main body of the ebb tidal delta is stable and undergoes little change. However, the swash bars located on the swash platform are very mobile, and probably account for the changes reported by the earlier assessments of changes between bathymetric surveys. In order to better track swash bars and assess variations in ebb-tidal delta morphology, multibeam echo sounder (MBES) surveys have been instituted.
Comparison of morphological changes with the dredging volume and the wave climate during 1998 to 2011 indicated that the storm events may trigger erosion of the ebb-tidal delta, particularly after a maintenance dredging campaign. However, the ebb-tidal delta volume recovered quickly between dredging campaigns, suggesting that the sediment was redistibuted within the system and not permanently removed.
To provide insights into the processes affecting the ebb-tidal delta, and provide the necessary data for the calibration and verification of numerical models, and a major 27-day field programme was undertaken. Sediment traps were used to assess sedimentaion rates, and provide sediment samples for characterising the
sediment grain size and bed roughness distribution for numerical modelling. Concentric arcs of wave and current recorders were used to measure hydrodynamic processes within and around the ebb-tidal delta and tidal inlet, and along the Matakana Island shoreface.
The field and historical bathymetric data showed that the ebb-tidal delta can be divided into 3 sub-regions according to the dominant hydrodynamic regime; (1) close to the Entrance Channel and ebb-jet where tidal currents dominate; (2) the central area of the swash platform, where the influence of tidal currents is still present but waves also play important role; and (3) the margins of the swash platform where waves are dominant and tidal influence is minimal. Overall the wave influence becomes more dominant as the distance from the Entrance Channel (main ebb jet) increases, and vice versa for tidal processes.
The short- and long-term impacts of dredging on the Matakana Banks ebb-tidal delta were investigated by numerical modelling using Delft3D. The model covered dredging locations inside Tauranga Harbour and the offshore areas around the Matakana Banks ebb-tidal delta, and was calibrated by the field measurement data. A month-long time series of wave conditions were used to force a wave model coupled with a hydrodynamic model for the 2013 bathymetry to simulate the present day situation. The modelling results showed that the sediment volume of the ebb-tidal delta fluctuates with tidal range; accretion occurred during neap tides; and erosion during spring tides.
To assess the long term impact, the morphological factor (morfac) tool in Delft3D was used. A morfac of 60 was applied to 12-days simulations to predict 2-year morphological changes, corresponding to the approximate time interval between maintenance dredging campaigns. The impacts of dredging were then investigated by modelling three different conditions: (1) before dredging started in 1968, using 1967 bathymetry; (2) the present situation using 2013 bathymetry with existing dredging and dumping activities; and (3) future scenarios using the 2013 bathymetry with alternative offshore disposal locations. Conditions of average waves (no storm) and with storm waves were also simulated.
Before dredging commenced, the ebb-tidal delta had a continuous terminal lobe from the north to southeast with a minimum depth of 5 m. Sediment transport modelling indicated that bar by-passing transported sediment past the inlet via mobile bedforms on the terminal lobe, and suggested that the ebb-tidal delta was getting shallower and broader.
Simulations incorporating dredging revealed that the tidal currents in the channels of the ebb-tidal delta became more asymmetric (stronger ebb-current), and the ebb-tidal delta became bifurcated and more complex in its morphology. The system changed to inlet bypassing, although only small quantities of sediment appear to be transported past the tidal inlet (most sediment recirculates within the tidal inlet system). Overall dredging does not appear to have affected the stability of the Matakana Banks ebb-tidal delta, but there may have been an increase in the morphologic variability as bedforms circulate over the swash platform, and additional bands of sand bars have formed on the seaward margin of the swash platform.
Modelling of alternative spoil disposal sites indicated that shallow nearshore spoil disposal sites were more rapidly dispersed than the offshore spoil disposal site in 20 m depth, particularly during storm events. However, the volumetric differences between the models were small (less than 0.2%). The smallest volumetric changes compared to an initial ebb-tidal delta volume are associated with spoil disposal located northeast of the ebb-tidal delta (DaD New), and the most effective site for contributing sediment to mitigate erosion of Matakana Island is on the shoreface to the west of the ebb-tidal delta.

text: The Impact of Dredging on the Stability of Matakana Banks Ebb-Tidal Delta The Matakana Banks ebb-tidal delta is located offshore from the Tauranga Entrance to Tauranga Harbour, Bay of Plenty New Zealand. In order to access the Port of Tauranga, Matakana Banks has been dredged to provide a shipping channel with sufficient depth for navigational purposes. In 1968 the first capital-dredging programme included an Entrance Channel through the delta, which was further enlarged in 1992. A biennial maintenance dredging programme has been required to deal with subsequent infilling of the Channel.
Recently, the Port has obtained resource consent to further widen and deepen the Entrance Channel. However, while granting the consent, the Environment Court accepted that dredging could result in adverse impacts to the stability of Matakana Banks and the adjacent Panepane Point on the western side of the tidal inlet. Therefore, this study was undertaken to assess the response of the ebb tidal delta to dredging, and determine possible mitigation measures if dredging has adverse effects.
The study analysed bathymetric data from single beam echo sounder (SBES) surveys obtained from 1998 to 2011. These data indicate that the main body of the ebb tidal delta is stable and undergoes little change. However, the swash bars located on the swash platform are very mobile, and probably account for the changes reported by the earlier assessments of changes between bathymetric surveys. In order to better track swash bars and assess variations in ebb-tidal delta morphology, multibeam echo sounder (MBES) surveys have been instituted.
Comparison of morphological changes with the dredging volume and the wave climate during 1998 to 2011 indicated that the storm events may trigger erosion of the ebb-tidal delta, particularly after a maintenance dredging campaign. However, the ebb-tidal delta volume recovered quickly between dredging campaigns, suggesting that the sediment was redistibuted within the system and not permanently removed.
To provide insights into the processes affecting the ebb-tidal delta, and provide the necessary data for the calibration and verification of numerical models, and a major 27-day field programme was undertaken. Sediment traps were used to assess sedimentaion rates, and provide sediment samples for characterising the
sediment grain size and bed roughness distribution for numerical modelling. Concentric arcs of wave and current recorders were used to measure hydrodynamic processes within and around the ebb-tidal delta and tidal inlet, and along the Matakana Island shoreface.
The field and historical bathymetric data showed that the ebb-tidal delta can be divided into 3 sub-regions according to the dominant hydrodynamic regime; (1) close to the Entrance Channel and ebb-jet where tidal currents dominate; (2) the central area of the swash platform, where the influence of tidal currents is still present but waves also play important role; and (3) the margins of the swash platform where waves are dominant and tidal influence is minimal. Overall the wave influence becomes more dominant as the distance from the Entrance Channel (main ebb jet) increases, and vice versa for tidal processes.
The short- and long-term impacts of dredging on the Matakana Banks ebb-tidal delta were investigated by numerical modelling using Delft3D. The model covered dredging locations inside Tauranga Harbour and the offshore areas around the Matakana Banks ebb-tidal delta, and was calibrated by the field measurement data. A month-long time series of wave conditions were used to force a wave model coupled with a hydrodynamic model for the 2013 bathymetry to simulate the present day situation. The modelling results showed that the sediment volume of the ebb-tidal delta fluctuates with tidal range; accretion occurred during neap tides; and erosion during spring tides.
To assess the long term impact, the morphological factor (morfac) tool in Delft3D was used. A morfac of 60 was applied to 12-days simulations to predict 2-year morphological changes, corresponding to the approximate time interval between maintenance dredging campaigns. The impacts of dredging were then investigated by modelling three different conditions: (1) before dredging started in 1968, using 1967 bathymetry; (2) the present situation using 2013 bathymetry with existing dredging and dumping activities; and (3) future scenarios using the 2013 bathymetry with alternative offshore disposal locations. Conditions of average waves (no storm) and with storm waves were also simulated.
Before dredging commenced, the ebb-tidal delta had a continuous terminal lobe from the north to southeast with a minimum depth of 5 m. Sediment transport modelling indicated that bar by-passing transported sediment past the inlet via mobile bedforms on the terminal lobe, and suggested that the ebb-tidal delta was getting shallower and broader.
Simulations incorporating dredging revealed that the tidal currents in the channels of the ebb-tidal delta became more asymmetric (stronger ebb-current), and the ebb-tidal delta became bifurcated and more complex in its morphology. The system changed to inlet bypassing, although only small quantities of sediment appear to be transported past the tidal inlet (most sediment recirculates within the tidal inlet system). Overall dredging does not appear to have affected the stability of the Matakana Banks ebb-tidal delta, but there may have been an increase in the morphologic variability as bedforms circulate over the swash platform, and additional bands of sand bars have formed on the seaward margin of the swash platform.
Modelling of alternative spoil disposal sites indicated that shallow nearshore spoil disposal sites were more rapidly dispersed than the offshore spoil disposal site in 20 m depth, particularly during storm events. However, the volumetric differences between the models were small (less than 0.2%). The smallest volumetric changes compared to an initial ebb-tidal delta volume are associated with spoil disposal located northeast of the ebb-tidal delta (DaD New), and the most effective site for contributing sediment to mitigate erosion of Matakana Island is on the shoreface to the west of the ebb-tidal delta.

year: 2016

title: Microstructure Dual-Refinement and Mechanical Properties Manipulation of TiBw/TA15(Si) Composites by Thermo-mechanical Processing and Heat Treatment

authors: Zhang, Rui

subjects: Titanium matrix composites

abstract: Titanium matrix composites with near-α titanium alloy as the matrix exhibit high specific strength and good high-temperature strength. However, the thermo-mechanical processing is limited by the brittleness of the reinforcement, making it difficult to refine the grain size and control the silicide precipitates. The present work aims to prepare titanium matrix composites with refined grain size and silicide particles. To this end, network-architecture TiBw/TA15(Si) composites were prepared using low-energy ball milling and vacuum hot-pressing. After refining the initial lamellar microstructure of the material through a solid solution treatment, the evolution of the TA15(Si) matrix and TiBw reinforcement during the hot deformation were studied. Ideal thermo-mechanical processing parameters in dual-phase region for TiBw/TA15(Si) composites after solid solution treatment was obtained, and the strain distribution in the compressive sample was revealed. Subsequently, TiBw/TA15(Si) composites with fine grains and dispersed silicide particles were obtained using solid solution treatment and isothermal hot-pressing, achieving a simultaneous improvement in room temperature strength and ductility. The influence mechanism of solid solution treatment on the microstructure and properties of the material was analyzed. Finally, TiBw/TA15(Si) composites with different lamellar content and morphologies were obtained through heat treatment of the deformed material. The effect of heat treatment on the microstructure of the material and the influence of different microstructures on the room temperature and high-temperature tensile mechanical behaviors of the material were discussed.
After compositional design through thermodynamic calculation, TiBw/TA15(Si) composites with different Si and Zr contents and a network architecture were prepared by low-energy ball milling and vacuum hot-pressing sintering using spherical TA15 coarse powder and TiB2, ZrB2, and Si fine powders. Silicide particles precipitated on the α/β interfaces in the matrix, and the precipitation amount increased with the increase of Si and Zr element contents. The tensile strength of materials with different compositions ranged from 1012 MPa to 1120 MPa, and the elongation ranged from 1.2% to 6.7%. When the Si content was between 0.3 wt.% and 1.0 wt.% and the Zr content was between 0.3 wt.% and 1.0 wt.%, the materials exhibited good strength and plasticity. By observing the microstructures of different materials subjected to heat treatment at 960°C to 1040°C for 30 min followed by quenching, it was found that silicide particles can be completely dissolved below β transformation temperature when the Si content is below 0.5 wt.%, which is suitable for microstructure control in dual-phase region. Considering the comprehensive mechanical properties and silicide dissolution temperature, a composite with a chemical composition of 3.4 vol.% TiBw/TA15-0.3 wt.%Si was selected for the study of dual-phase region thermo-mechanical processing and microstructure control.
After the solid solution treatment in single-phase region, the initial microstructure of TiBw/TA15(Si) was refined, after that, the high-temperature deformation behavior of the material was studied. The hot compression tests were conducted in dual-phase region at temperatures ranging from 870°C to 950°C and strain rates ranging from 1 s-1 to 0.001 s-1. It was found that the compressive stress-strain curves of the composite in this range exhibited dynamic recrystallization features, and the compressive stress decreased with increasing deformation temperature and decreasing strain rate. Except for the fully lath overheated-microstructure observed at 950°C / 1 s-1, the deformation microstructure of the material under the remaining conditions consisted of equiaxed α grains and residual α/β laths. The microstructure became finer with lower deformation temperature and higher strain rate. Higher recrystallization degree was observed below 910°C at lower strain rates, while the opposite was observed above 910°C. Observation of the microstructure produced by different deformation degrees revealed that the formation of equiaxed grains in the material involved three steps: α/β lath distortion, formation of boundaries within α/β laths, and lath decomposition. The activation energy for hot deformation of the TiBw/TA15(Si) composite after single-phase solid solution pretreatment was determined to be 623 kJ/mol. Based on the constructed processing map, the ideal deformation parameters were determined to be in the temperature range of 900°C to 950°C and strain rates of 0.01 s-1 to 0.001 s-1.
The orientation distribution of TiBw reinforcements during high-temperature plastic deformation in materials has been studied. The rotational behavior of TiBw reinforcements during deformation was analyzed, revealing that the orientation distribution of the reinforcements is influenced by the direction and magnitude of the principal strain applied to the material. The direction of the principal strain determines the principal directions of covariance matrix for the reinforcement's orientation distribution, while the magnitude of the principal strain determines the parameters in the probability density function. Based on these findings, a method was proposed to calculate the local plastic deformation in materials using the orientation distribution of TiBw reinforcements. Error analysis through computer simulations showed that this method exhibited good accuracy in the range of 20% to 80% compression strain. Using this method, the strain distribution in hot-deformed TiBw/TA15(Si) composites was analyzed, and the accuracy of the calculations was confirmed by comparing them with the deformation of the network structure of TiBw.
Based on the results of hot compression tests, TiBw/TA15(Si) composites were subjected to a solid solution treatment followed by isothermal hot pressing at 920 °C and a strain rate of 0.003 s-1 with 75% height reduction. This process yielded a microstructure with fine equiaxed α grains and dispersed fine silicide particles, with an average grain size of 1.6 μm and particle size of 70 μm, respectively, achieving a dual-refinement of both α grains and silicide particles. The composite exhibited a yield strength of 1100 MPa and an elongation of 7.7%. A comparison showed that the solid solution pretreatment led to finer grains and more dispersed silicide particles in the material after isothermal hot pressing, resulting in a significant increase in yield strength. 
Heat treatment of the hot-pressed composite in the range of 980 °C to 1050 °C revealed that higher temperatures led to higher contents of α/β laths and coarser microstructures, while faster cooling rates resulted in finer lath structures. Water quenching after the heat treatment at 1010 °C for 30 min produced excellent room temperature strength and ductility, with a tensile strength of 1350 MPa and an elongation of 6.7%. Slip trace analysis and transmission electron microscopy analysis revealed that the equiaxed microstructure in the material facilitated multi-system slip, enhancing deformation uniformity. The prismatic slip in lamellar microstructure obtained with air cooling was suppressed by the Burgers orientation relationship, the strain-softening of the lamellae resulted in deformation dominated by single-system slip and strain localization. The transformed β phase obtained through water quenching exhibited limited deformability, which was primarily accommodated by the prismatic slip of primary α laths. High-temperature tensile tests under different conditions showed that decreasing the deformation temperature, increasing the strain rate, refining the grain size, and decreasing the α/β lath content transform the deformation mechanism into grain boundary sliding, which significantly enhances the deformability of TiBw/TA15(Si) composites. The composite with fine equiaxed microstructure could achieve an elongation up to 348% at 800 °C and a strain rate of 0.0003 s-1, which showed a good potential for superplastic forming at low temperatures.

text: Microstructure Dual-Refinement and Mechanical Properties Manipulation of TiBw/TA15(Si) Composites by Thermo-mechanical Processing and Heat Treatment Titanium matrix composites with near-α titanium alloy as the matrix exhibit high specific strength and good high-temperature strength. However, the thermo-mechanical processing is limited by the brittleness of the reinforcement, making it difficult to refine the grain size and control the silicide precipitates. The present work aims to prepare titanium matrix composites with refined grain size and silicide particles. To this end, network-architecture TiBw/TA15(Si) composites were prepared using low-energy ball milling and vacuum hot-pressing. After refining the initial lamellar microstructure of the material through a solid solution treatment, the evolution of the TA15(Si) matrix and TiBw reinforcement during the hot deformation were studied. Ideal thermo-mechanical processing parameters in dual-phase region for TiBw/TA15(Si) composites after solid solution treatment was obtained, and the strain distribution in the compressive sample was revealed. Subsequently, TiBw/TA15(Si) composites with fine grains and dispersed silicide particles were obtained using solid solution treatment and isothermal hot-pressing, achieving a simultaneous improvement in room temperature strength and ductility. The influence mechanism of solid solution treatment on the microstructure and properties of the material was analyzed. Finally, TiBw/TA15(Si) composites with different lamellar content and morphologies were obtained through heat treatment of the deformed material. The effect of heat treatment on the microstructure of the material and the influence of different microstructures on the room temperature and high-temperature tensile mechanical behaviors of the material were discussed.
After compositional design through thermodynamic calculation, TiBw/TA15(Si) composites with different Si and Zr contents and a network architecture were prepared by low-energy ball milling and vacuum hot-pressing sintering using spherical TA15 coarse powder and TiB2, ZrB2, and Si fine powders. Silicide particles precipitated on the α/β interfaces in the matrix, and the precipitation amount increased with the increase of Si and Zr element contents. The tensile strength of materials with different compositions ranged from 1012 MPa to 1120 MPa, and the elongation ranged from 1.2% to 6.7%. When the Si content was between 0.3 wt.% and 1.0 wt.% and the Zr content was between 0.3 wt.% and 1.0 wt.%, the materials exhibited good strength and plasticity. By observing the microstructures of different materials subjected to heat treatment at 960°C to 1040°C for 30 min followed by quenching, it was found that silicide particles can be completely dissolved below β transformation temperature when the Si content is below 0.5 wt.%, which is suitable for microstructure control in dual-phase region. Considering the comprehensive mechanical properties and silicide dissolution temperature, a composite with a chemical composition of 3.4 vol.% TiBw/TA15-0.3 wt.%Si was selected for the study of dual-phase region thermo-mechanical processing and microstructure control.
After the solid solution treatment in single-phase region, the initial microstructure of TiBw/TA15(Si) was refined, after that, the high-temperature deformation behavior of the material was studied. The hot compression tests were conducted in dual-phase region at temperatures ranging from 870°C to 950°C and strain rates ranging from 1 s-1 to 0.001 s-1. It was found that the compressive stress-strain curves of the composite in this range exhibited dynamic recrystallization features, and the compressive stress decreased with increasing deformation temperature and decreasing strain rate. Except for the fully lath overheated-microstructure observed at 950°C / 1 s-1, the deformation microstructure of the material under the remaining conditions consisted of equiaxed α grains and residual α/β laths. The microstructure became finer with lower deformation temperature and higher strain rate. Higher recrystallization degree was observed below 910°C at lower strain rates, while the opposite was observed above 910°C. Observation of the microstructure produced by different deformation degrees revealed that the formation of equiaxed grains in the material involved three steps: α/β lath distortion, formation of boundaries within α/β laths, and lath decomposition. The activation energy for hot deformation of the TiBw/TA15(Si) composite after single-phase solid solution pretreatment was determined to be 623 kJ/mol. Based on the constructed processing map, the ideal deformation parameters were determined to be in the temperature range of 900°C to 950°C and strain rates of 0.01 s-1 to 0.001 s-1.
The orientation distribution of TiBw reinforcements during high-temperature plastic deformation in materials has been studied. The rotational behavior of TiBw reinforcements during deformation was analyzed, revealing that the orientation distribution of the reinforcements is influenced by the direction and magnitude of the principal strain applied to the material. The direction of the principal strain determines the principal directions of covariance matrix for the reinforcement's orientation distribution, while the magnitude of the principal strain determines the parameters in the probability density function. Based on these findings, a method was proposed to calculate the local plastic deformation in materials using the orientation distribution of TiBw reinforcements. Error analysis through computer simulations showed that this method exhibited good accuracy in the range of 20% to 80% compression strain. Using this method, the strain distribution in hot-deformed TiBw/TA15(Si) composites was analyzed, and the accuracy of the calculations was confirmed by comparing them with the deformation of the network structure of TiBw.
Based on the results of hot compression tests, TiBw/TA15(Si) composites were subjected to a solid solution treatment followed by isothermal hot pressing at 920 °C and a strain rate of 0.003 s-1 with 75% height reduction. This process yielded a microstructure with fine equiaxed α grains and dispersed fine silicide particles, with an average grain size of 1.6 μm and particle size of 70 μm, respectively, achieving a dual-refinement of both α grains and silicide particles. The composite exhibited a yield strength of 1100 MPa and an elongation of 7.7%. A comparison showed that the solid solution pretreatment led to finer grains and more dispersed silicide particles in the material after isothermal hot pressing, resulting in a significant increase in yield strength. 
Heat treatment of the hot-pressed composite in the range of 980 °C to 1050 °C revealed that higher temperatures led to higher contents of α/β laths and coarser microstructures, while faster cooling rates resulted in finer lath structures. Water quenching after the heat treatment at 1010 °C for 30 min produced excellent room temperature strength and ductility, with a tensile strength of 1350 MPa and an elongation of 6.7%. Slip trace analysis and transmission electron microscopy analysis revealed that the equiaxed microstructure in the material facilitated multi-system slip, enhancing deformation uniformity. The prismatic slip in lamellar microstructure obtained with air cooling was suppressed by the Burgers orientation relationship, the strain-softening of the lamellae resulted in deformation dominated by single-system slip and strain localization. The transformed β phase obtained through water quenching exhibited limited deformability, which was primarily accommodated by the prismatic slip of primary α laths. High-temperature tensile tests under different conditions showed that decreasing the deformation temperature, increasing the strain rate, refining the grain size, and decreasing the α/β lath content transform the deformation mechanism into grain boundary sliding, which significantly enhances the deformability of TiBw/TA15(Si) composites. The composite with fine equiaxed microstructure could achieve an elongation up to 348% at 800 °C and a strain rate of 0.0003 s-1, which showed a good potential for superplastic forming at low temperatures.

year: 2024

title: Ngā takenga o te riri

authors: Murphy, Ēnoka

subjects: Pakanga

abstract: Ko te kaupapa ake o tēnei tuhinga, ko te whakawhāriki i ētahi kōrero mō te takenga mai o te riri, o te pakanga ki tā rā ngā kōrero a te Māori. Ko aua take mai rā kei ngā kōrero o tua whakarere, e hokia ana ki a Ranginui rāua ko Papatūānuku me tā rāua hūnuku. Ko tāna e pātai ake nei, nō hea ake te riri Māori, otirā, te pakanga a te Māori? Nō hea anō hoki āna tikanga? He aha ā ērā kōrero tauiratanga mai ki te toa o te Māori ki te whawhai. Ka mutu, ko te wāhi uaua pea o ngā pātai nei, ko te āhua ki ngā kōrero a te Māori kāore nei i te tapatahi mō te oroko hīmatanga. Ahakoa rā, tērā ōna rite, ōna rerekē. Kua tuhia nuitia te kaupapa o te oroko tīmatanga mai o te ao e ngā momo o te kaituhi Pākehā, ā, tērā anō hoki ko ngā tuhinga a te Māori ake. Inā te rerekē o ngā kōrero mō te oroko hīmatanga mai o te ao, tērā noa ētahi kōrero kua tīkina hei mātaitanga mō tēnei rangahau, mō tēnei tuhinga. Ka mutu, ko tā tēnei tuhinga, he whakaatu i te takenga mai o te riri, o te matawhāura Māori.

text: Ngā takenga o te riri Ko te kaupapa ake o tēnei tuhinga, ko te whakawhāriki i ētahi kōrero mō te takenga mai o te riri, o te pakanga ki tā rā ngā kōrero a te Māori. Ko aua take mai rā kei ngā kōrero o tua whakarere, e hokia ana ki a Ranginui rāua ko Papatūānuku me tā rāua hūnuku. Ko tāna e pātai ake nei, nō hea ake te riri Māori, otirā, te pakanga a te Māori? Nō hea anō hoki āna tikanga? He aha ā ērā kōrero tauiratanga mai ki te toa o te Māori ki te whawhai. Ka mutu, ko te wāhi uaua pea o ngā pātai nei, ko te āhua ki ngā kōrero a te Māori kāore nei i te tapatahi mō te oroko hīmatanga. Ahakoa rā, tērā ōna rite, ōna rerekē. Kua tuhia nuitia te kaupapa o te oroko tīmatanga mai o te ao e ngā momo o te kaituhi Pākehā, ā, tērā anō hoki ko ngā tuhinga a te Māori ake. Inā te rerekē o ngā kōrero mō te oroko hīmatanga mai o te ao, tērā noa ētahi kōrero kua tīkina hei mātaitanga mō tēnei rangahau, mō tēnei tuhinga. Ka mutu, ko tā tēnei tuhinga, he whakaatu i te takenga mai o te riri, o te matawhāura Māori.

year: 2017