title: Ecological modelling of water quality management options in Lake Waahi to support Hauanga Kai species: Technical Report

authors: Allan, Mathew Grant

abstract: This report describes a numerical modelling approach for Lake Waahi to assess the effects of various future scenarios on water quality attributes known to affect the appearance of the lake’s multiple hauanga kai species across differing spatial scales. Hauanga kai refers to customary gathering and use of naturally occurring and cultivated foods. Numerical models were used to support shared learning and development of future scenarios in response to different management options and environmental pressures. The shallow lakes of the Waikato region have been particularly impacted by anthropogenic eutrophication. This is due to the fact that many of these lakes have already undergone a degree of natural eutrophication due to their geomorphic properties, such as their low elevation and shallow depth. The main contributing factors to water quality decline in shallow Waikato lakes have been identified as: high external nutrient and sediment loads, internal loading exacerbated by high sediment resuspension and bioturbation from pest fish (carp), reduced water depth due to installation of water control structures, reduction in wetland filtering potential due to draining, and stock access to wetlands. A 1-D hydrodynamics model, the General Ocean Turbulence Model was coupled to a complex ecological model (PClake) via the Framework for Aquatic Biogeochemical Models (FABM). FABM is an open source FORTAN-based code that facilitates the coupling of hydrodynamic and ecological models. FABM-PCLake is a redesigned PCLake. The consensus from the model simulations carried out in the study suggests that, for Lake Waahi to undergo restoration whereby the lake is restored to clear-water stable state, both external load needs to be reduced significantly by greater than 50%, along with changes in lake ecological structure, resulting from re-establishment of macrophytes aided by the control of carp biomass. These finding supports the general view within the literature that for lake restoration success, external load reduction (catchment load) is critical. Finally, if the ultimate goal of lake restoration in Lake Waahi is to address the decline in tuna (shortfin eel - Anguilla australis) biomass, a return to a clear-water stable state should facilitate improvement in tuna habitat and provide the conditions for development of a healthy eel population. Coupled modelling approaches will provide a more complete picture of potential responses of Hauanga kai species to land and lake management scenarios.

text: Ecological modelling of water quality management options in Lake Waahi to support Hauanga Kai species: Technical Report This report describes a numerical modelling approach for Lake Waahi to assess the effects of various future scenarios on water quality attributes known to affect the appearance of the lake’s multiple hauanga kai species across differing spatial scales. Hauanga kai refers to customary gathering and use of naturally occurring and cultivated foods. Numerical models were used to support shared learning and development of future scenarios in response to different management options and environmental pressures. The shallow lakes of the Waikato region have been particularly impacted by anthropogenic eutrophication. This is due to the fact that many of these lakes have already undergone a degree of natural eutrophication due to their geomorphic properties, such as their low elevation and shallow depth. The main contributing factors to water quality decline in shallow Waikato lakes have been identified as: high external nutrient and sediment loads, internal loading exacerbated by high sediment resuspension and bioturbation from pest fish (carp), reduced water depth due to installation of water control structures, reduction in wetland filtering potential due to draining, and stock access to wetlands. A 1-D hydrodynamics model, the General Ocean Turbulence Model was coupled to a complex ecological model (PClake) via the Framework for Aquatic Biogeochemical Models (FABM). FABM is an open source FORTAN-based code that facilitates the coupling of hydrodynamic and ecological models. FABM-PCLake is a redesigned PCLake. The consensus from the model simulations carried out in the study suggests that, for Lake Waahi to undergo restoration whereby the lake is restored to clear-water stable state, both external load needs to be reduced significantly by greater than 50%, along with changes in lake ecological structure, resulting from re-establishment of macrophytes aided by the control of carp biomass. These finding supports the general view within the literature that for lake restoration success, external load reduction (catchment load) is critical. Finally, if the ultimate goal of lake restoration in Lake Waahi is to address the decline in tuna (shortfin eel - Anguilla australis) biomass, a return to a clear-water stable state should facilitate improvement in tuna habitat and provide the conditions for development of a healthy eel population. Coupled modelling approaches will provide a more complete picture of potential responses of Hauanga kai species to land and lake management scenarios.

year: 2018

title: John William Richard Guilding

authors: Hart, Philip

abstract: Born in Auckland in 1842, by his late teenage years John William Richard Guilding was trading with Maori in the Piako district. Protected by a rangatira, he established a store at Kerepehi, but despite being known to be ‘friendly’ with Maori he was driven off after the start of the Waikato War. In 1864, again with the approval of a rangatira, he erected a store on the site of the future township of Thames. Although he claimed to have found signs of gold there, he was not the prospector who produced the samples that led to the opening of the goldfield. In 1869 he was appointed a licensed interpreter, in which role he assisted both the Crown and private individuals to acquire Maori land. Some of these transactions created controversy, and he was accused of tricking Maori. In 1875 his attempt to use his position as James Mackay’s interpreter to acquire a lease of land at Tairua for his own financial gain provoked much criticism, and his ‘irregular practices’ led to his dismissal as a licensed interpreter in 1883. He would continue to act for individuals as both an interpreter and a land agent in Ohinemuri and Te Aroha in subsequent years.
Guilding’s close links with Maori were in part explained by his private life. Having married a ‘half-caste’ who later left him for another man, he had three more ‘marriages’ and several more children, who were brought up in Pakeha ways. Financially, he always struggled, filing as bankrupt twice and dying in straightened circumstances. At Te Aroha he held several minor official positions, sometimes being criticized for his performance. Active in local politics, he was generally unpopular and was never elected to the positions he sought. Throughout his life his reputation amongst a sizeable number of his contemporaries was poor.

text: John William Richard Guilding Born in Auckland in 1842, by his late teenage years John William Richard Guilding was trading with Maori in the Piako district. Protected by a rangatira, he established a store at Kerepehi, but despite being known to be ‘friendly’ with Maori he was driven off after the start of the Waikato War. In 1864, again with the approval of a rangatira, he erected a store on the site of the future township of Thames. Although he claimed to have found signs of gold there, he was not the prospector who produced the samples that led to the opening of the goldfield. In 1869 he was appointed a licensed interpreter, in which role he assisted both the Crown and private individuals to acquire Maori land. Some of these transactions created controversy, and he was accused of tricking Maori. In 1875 his attempt to use his position as James Mackay’s interpreter to acquire a lease of land at Tairua for his own financial gain provoked much criticism, and his ‘irregular practices’ led to his dismissal as a licensed interpreter in 1883. He would continue to act for individuals as both an interpreter and a land agent in Ohinemuri and Te Aroha in subsequent years.
Guilding’s close links with Maori were in part explained by his private life. Having married a ‘half-caste’ who later left him for another man, he had three more ‘marriages’ and several more children, who were brought up in Pakeha ways. Financially, he always struggled, filing as bankrupt twice and dying in straightened circumstances. At Te Aroha he held several minor official positions, sometimes being criticized for his performance. Active in local politics, he was generally unpopular and was never elected to the positions he sought. Throughout his life his reputation amongst a sizeable number of his contemporaries was poor.

year: 2016

title: Work distribution of multiple Cartesian robot arms for kiwifruit harvesting

authors: Barnett, Josh

subjects: Science & Technology

abstract: Employing multiple robot arms for kiwifruit harvesting can raise the efficiency since the task completion time is shortened. However, task partitioning and reachability are two major concerns. It is found that the task completion time is minimized if task partitions for robot arms are uniform. However, the partition uniformity is influenced by the fruit indivisibility and fruit cluster growing style. It is also constrained by the fruit distribution across the canopy and the robot arm positions which affect the fruit reachability. This article investigates how to partition the tasks of kiwifruit harvesting so that the harvesting can be completed by multiple robot arms in the minimum time with an assumption that the fruits can be harvested by any robot arm. A parameter termed work distribution is introduced to measure how the task partitioning is different from the optimum. A research platform with two robot arms is implemented to show how to approximate the assumption. Ten field experiments of kiwifruit harvesting had been run by the research platform in two kiwifruit orchards in New Zealand with satisfactory outcomes.

text: Work distribution of multiple Cartesian robot arms for kiwifruit harvesting Employing multiple robot arms for kiwifruit harvesting can raise the efficiency since the task completion time is shortened. However, task partitioning and reachability are two major concerns. It is found that the task completion time is minimized if task partitions for robot arms are uniform. However, the partition uniformity is influenced by the fruit indivisibility and fruit cluster growing style. It is also constrained by the fruit distribution across the canopy and the robot arm positions which affect the fruit reachability. This article investigates how to partition the tasks of kiwifruit harvesting so that the harvesting can be completed by multiple robot arms in the minimum time with an assumption that the fruits can be harvested by any robot arm. A parameter termed work distribution is introduced to measure how the task partitioning is different from the optimum. A research platform with two robot arms is implemented to show how to approximate the assumption. Ten field experiments of kiwifruit harvesting had been run by the research platform in two kiwifruit orchards in New Zealand with satisfactory outcomes.

year: 2020-02-01