title: Effect of exposure on the erodibility of intertidal mudflats

authors: Nguyen, Hieu Manh

abstract: Sediments on intertidal flats are exposed during low tides. Under the effect of exposure, the water content of sediments decreases because of the evaporation process, which alters the erosive behaviour of cohesive sediments, and therefore changes the patterns of erosion/accretion on intertidal flats. Consequently, exposure indirectly affects the intertidal morphology. An understanding of how exposure alters the erodibility of sediment on intertidal flats is critical to predicting the resilience of intertidal zones into the future during which sea-level rise is believed to exacerbate erosion in low-lying areas. 

Sediments were collected from an intertidal mudflat in the Firth of Thames, New Zealand in different seasons from 2017 to 2019 for laboratory experiments. Two experiments (Exp. 1 and Exp. 2) were set up in order to explore the effect of exposure including air temperature and exposure duration on erodibility of cohesive sediments. The EROMES device was used to measure the erosion potential of sediment (erosion threshold, Ƭ𝒸ᵣ N m⁻² and erosion rate, ER g m⁻² s⁻¹). Exp. 1 investigated erodibility of sediments exposed to a wide range of temperatures (controlled at 0, 8, 25 and 40°C) for 6 h. Meanwhile, Exp. 2 was designed to examine the effect of exposure duration on erodibility. In this experiment, a systematically-changed exposure duration (6 h, 1, 4 and 10 d) was used to mimic a wide range of exposure that might happen on an intertidal flat during a year (set to mimic the Firth of Thames field site). Experimental results indicated that erosion resistance of sediments significantly increased (increased Ƭ𝒸ᵣ, and decreased ER) corresponding to decreased water content after exposure. The higher the air temperature and the longer the exposure duration, the more stable the sediments were. For instance, the water content of exposed sediments decreased by 1.01 to 1.78 times, a rate which was a function of increasing temperature. The Ƭ𝒸ᵣ of exposed experiments was 1.2 to 2.2 times higher, whereas ER decreased 1.2 to 6.2 times. After 10 d, exposure increased Ƭ𝒸ᵣ by 1.7 to 4.4 times and decreased ER by 11.6 to 21.5 times compared with 6 h of exposure. 

Semi-empirical models fitted datasets from Exp.1 and Exp. 2 were used to predict the variations of Ƭ𝒸ᵣ and ER as functions of air temperature, T (°C) and exposure duration, D (h). These semi-empirical models were used to extend a Delft3D numerical model to test the effect of exposure on intertidal mudflat profiles and development of tidal channel networks. Model results indicated that exposure enhanced the more flat-topped shape of intertidal mudflats. Higher air temperature resulted in stronger effects on bed level change. For example, for the case of 40°C, bed level built up by 0.039m after one year of model time. Regarding the development of channel networks on intertidal mudflats, the exposure effect tended to create denser and deeper channel networks compared to model runs without the exposure effect. Our findings, therefore, contribute to the prediction of the intertidal morphology development, which will help to understanding the resilience of tidal flats and salt marshes in future under the effect of sea-level rise and global warming.

text: Effect of exposure on the erodibility of intertidal mudflats Sediments on intertidal flats are exposed during low tides. Under the effect of exposure, the water content of sediments decreases because of the evaporation process, which alters the erosive behaviour of cohesive sediments, and therefore changes the patterns of erosion/accretion on intertidal flats. Consequently, exposure indirectly affects the intertidal morphology. An understanding of how exposure alters the erodibility of sediment on intertidal flats is critical to predicting the resilience of intertidal zones into the future during which sea-level rise is believed to exacerbate erosion in low-lying areas. 

Sediments were collected from an intertidal mudflat in the Firth of Thames, New Zealand in different seasons from 2017 to 2019 for laboratory experiments. Two experiments (Exp. 1 and Exp. 2) were set up in order to explore the effect of exposure including air temperature and exposure duration on erodibility of cohesive sediments. The EROMES device was used to measure the erosion potential of sediment (erosion threshold, Ƭ𝒸ᵣ N m⁻² and erosion rate, ER g m⁻² s⁻¹). Exp. 1 investigated erodibility of sediments exposed to a wide range of temperatures (controlled at 0, 8, 25 and 40°C) for 6 h. Meanwhile, Exp. 2 was designed to examine the effect of exposure duration on erodibility. In this experiment, a systematically-changed exposure duration (6 h, 1, 4 and 10 d) was used to mimic a wide range of exposure that might happen on an intertidal flat during a year (set to mimic the Firth of Thames field site). Experimental results indicated that erosion resistance of sediments significantly increased (increased Ƭ𝒸ᵣ, and decreased ER) corresponding to decreased water content after exposure. The higher the air temperature and the longer the exposure duration, the more stable the sediments were. For instance, the water content of exposed sediments decreased by 1.01 to 1.78 times, a rate which was a function of increasing temperature. The Ƭ𝒸ᵣ of exposed experiments was 1.2 to 2.2 times higher, whereas ER decreased 1.2 to 6.2 times. After 10 d, exposure increased Ƭ𝒸ᵣ by 1.7 to 4.4 times and decreased ER by 11.6 to 21.5 times compared with 6 h of exposure. 

Semi-empirical models fitted datasets from Exp.1 and Exp. 2 were used to predict the variations of Ƭ𝒸ᵣ and ER as functions of air temperature, T (°C) and exposure duration, D (h). These semi-empirical models were used to extend a Delft3D numerical model to test the effect of exposure on intertidal mudflat profiles and development of tidal channel networks. Model results indicated that exposure enhanced the more flat-topped shape of intertidal mudflats. Higher air temperature resulted in stronger effects on bed level change. For example, for the case of 40°C, bed level built up by 0.039m after one year of model time. Regarding the development of channel networks on intertidal mudflats, the exposure effect tended to create denser and deeper channel networks compared to model runs without the exposure effect. Our findings, therefore, contribute to the prediction of the intertidal morphology development, which will help to understanding the resilience of tidal flats and salt marshes in future under the effect of sea-level rise and global warming.

year: 2021

title: Making global audiences for a Hollywood ‘blockbuster’ feature film: Marketability, playability and The Hobbit: An Unexpected Journey (2012)

authors: Davis, Charles H.

subjects: fans

abstract: This article interprets two key concepts in movie marketing (marketability and play-ability) through an empirical examination of the effects of commercial interpellation of audiences for a Hollywood ‘blockbuster’ fantasy film, Peter Jackson’s The Hobbit: An Unexpected Journey (2012). The article reports results of two online surveys of Hobbit audiences, one in November 2012 in the weeks preceding theatrical release, and one in February–June 2013 among post-viewing audiences, employing a mixed-methods approach that includes Q sorting and a questionnaire. We identify and describe five main pre-release and five main post-viewing audience groups, show-ing that the film had greater marketability than playability. Three of the pre-release audience groups expressed a high degree of anticipation to see the film, but only one post-viewing audience group expressed a high degree of enjoyment, while the others expressed various degrees of disappointment. We discuss the attributes of the film that most affected the film’s marketability and playability for each of the audience groups during the interpellation process from prefiguration to reception.

text: Making global audiences for a Hollywood ‘blockbuster’ feature film: Marketability, playability and The Hobbit: An Unexpected Journey (2012) This article interprets two key concepts in movie marketing (marketability and play-ability) through an empirical examination of the effects of commercial interpellation of audiences for a Hollywood ‘blockbuster’ fantasy film, Peter Jackson’s The Hobbit: An Unexpected Journey (2012). The article reports results of two online surveys of Hobbit audiences, one in November 2012 in the weeks preceding theatrical release, and one in February–June 2013 among post-viewing audiences, employing a mixed-methods approach that includes Q sorting and a questionnaire. We identify and describe five main pre-release and five main post-viewing audience groups, show-ing that the film had greater marketability than playability. Three of the pre-release audience groups expressed a high degree of anticipation to see the film, but only one post-viewing audience group expressed a high degree of enjoyment, while the others expressed various degrees of disappointment. We discuss the attributes of the film that most affected the film’s marketability and playability for each of the audience groups during the interpellation process from prefiguration to reception.

year: 2016

title: Waata Kukutai: Rangatira o Ngaati Tiipa 1822-1867

authors: Ewe, Denise Te Tuhi

subjects: Biography

abstract: This thesis examines the life of Ngaati Tiipa rangatira Waata Kukutai (1822-1867), and critiques historical perspectives that have narrowly identified him as merely a Kuupapa loyalist. This study argues that Kukutai’s choices and leadership were driven first and foremost by those things he viewed as crucial to Ngaati Tiipa autonomy and wellbeing. Kukutai was an articulate and well-educated leader of Ngaati Tiipa. Waata was governed by principles of rangatiratanga (chieftainship), mana motuhake (independence) and loyalty to Ngaati Tiipa and to the whenua. He was deeply religious and courageous and was an entrepreneur who sought to protect his people by securing economic independence. This thesis shows how he negotiated colonial structures by forming strategic alliances, and in the process led his people through one of the most turbulent periods in New Zealand history.  

Waata was an enigma shaped by loss, vision and hope for a new future in extraordinary times in New Zealand’s history. Waata was a polarising personality who held fast to his life principles. He withstood immense pressure from other Waikato chiefs during the Waikato invasion. During the Waikato War Waata was most active, carrying letters, food and supplies to colonial soldiers and earned himself and his tribe of Ngaati Tiipa the label of kuupapa. While Waata was not the only ‘friendly chief’ during colonial times he has been the most pillorised in Waikato. Seemingly ignored by many historians is at the same time Waata ensued that Ngaati Tiipa land was never invaded by the colonial troops. Waata’s actions protected his people and his land and maintained his mana motuhake, his sovereignty over his district.

text: Waata Kukutai: Rangatira o Ngaati Tiipa 1822-1867 This thesis examines the life of Ngaati Tiipa rangatira Waata Kukutai (1822-1867), and critiques historical perspectives that have narrowly identified him as merely a Kuupapa loyalist. This study argues that Kukutai’s choices and leadership were driven first and foremost by those things he viewed as crucial to Ngaati Tiipa autonomy and wellbeing. Kukutai was an articulate and well-educated leader of Ngaati Tiipa. Waata was governed by principles of rangatiratanga (chieftainship), mana motuhake (independence) and loyalty to Ngaati Tiipa and to the whenua. He was deeply religious and courageous and was an entrepreneur who sought to protect his people by securing economic independence. This thesis shows how he negotiated colonial structures by forming strategic alliances, and in the process led his people through one of the most turbulent periods in New Zealand history.  

Waata was an enigma shaped by loss, vision and hope for a new future in extraordinary times in New Zealand’s history. Waata was a polarising personality who held fast to his life principles. He withstood immense pressure from other Waikato chiefs during the Waikato invasion. During the Waikato War Waata was most active, carrying letters, food and supplies to colonial soldiers and earned himself and his tribe of Ngaati Tiipa the label of kuupapa. While Waata was not the only ‘friendly chief’ during colonial times he has been the most pillorised in Waikato. Seemingly ignored by many historians is at the same time Waata ensued that Ngaati Tiipa land was never invaded by the colonial troops. Waata’s actions protected his people and his land and maintained his mana motuhake, his sovereignty over his district.

year: 2020