title: Colour classification of 1486 lakes across a wide range of optical water types

authors: Lehmann, Moritz K.

subjects: lakes

abstract: Remote sensing by satellite-borne sensors presents a significant opportunity to enhance the spatio-temporal coverage of environmental monitoring programmes for lakes, but the estimation of classic water quality attributes from inland water bodies has not reached operational status due to the difficulty of discerning the spectral signatures of optically active water constituents. Determination of water colour, as perceived by the human eye, does not require knowledge of inherent optical properties and therefore represents a generally applicable remotely-sensed water quality attribute. In this paper, we implemented a recent algorithm for the retrieval of colour parameters (hue angle, dominant wavelength) and derived a new correction for colour purity to account for the spectral bandpass of the Landsat 8 Operational Land Imager (OLI). We used this algorithm to calculate water colour on almost 45,000 observations over four years from 1486 lakes from a diverse range of optical water types in New Zealand. We show that the most prevalent lake colours are yellow-orange and blue, respectively, while green observations are comparatively rare. About 40% of the study lakes show transitions between colours at a range of time scales, including seasonal. A preliminary exploratory analysis suggests that both geo-physical and anthropogenic factors, such as catchment land use, provide environmental control of lake colour and are promising avenues for future analysis.

text: Colour classification of 1486 lakes across a wide range of optical water types Remote sensing by satellite-borne sensors presents a significant opportunity to enhance the spatio-temporal coverage of environmental monitoring programmes for lakes, but the estimation of classic water quality attributes from inland water bodies has not reached operational status due to the difficulty of discerning the spectral signatures of optically active water constituents. Determination of water colour, as perceived by the human eye, does not require knowledge of inherent optical properties and therefore represents a generally applicable remotely-sensed water quality attribute. In this paper, we implemented a recent algorithm for the retrieval of colour parameters (hue angle, dominant wavelength) and derived a new correction for colour purity to account for the spectral bandpass of the Landsat 8 Operational Land Imager (OLI). We used this algorithm to calculate water colour on almost 45,000 observations over four years from 1486 lakes from a diverse range of optical water types in New Zealand. We show that the most prevalent lake colours are yellow-orange and blue, respectively, while green observations are comparatively rare. About 40% of the study lakes show transitions between colours at a range of time scales, including seasonal. A preliminary exploratory analysis suggests that both geo-physical and anthropogenic factors, such as catchment land use, provide environmental control of lake colour and are promising avenues for future analysis.

year: 2018

title: Teaching students to critically evaluate the quality of Internet research resources

authors: Cunningham, Sally Jo

subjects: computer science

abstract: The Internet offers a host of high-quality research material in computer science-and, unfortunately, some very low quality resources as well. As part of learning the research process, students should be taught to critically evaluate the quality of all documents that they use. This paper discusses the application of document evaluation criteria to WWW resources, and describes activities for including quality evaluation in a course on research methods.

text: Teaching students to critically evaluate the quality of Internet research resources The Internet offers a host of high-quality research material in computer science-and, unfortunately, some very low quality resources as well. As part of learning the research process, students should be taught to critically evaluate the quality of all documents that they use. This paper discusses the application of document evaluation criteria to WWW resources, and describes activities for including quality evaluation in a course on research methods.

year: 1996-11

title: Revitalizing Te Ika-a-Maui: Māori migration and the nation

authors: Mahuika, Nepia

subjects: Māori

abstract: Maui-Tikitiki-A-Taranga is more than simply a ‘mythic’ hero. For many he is a prominent figure in a long family line. The whakapapa that binds Māori to our tupuna is significant to the present and future, and carries with it the ‘ultimate expression’ of who we are. Maui has been described as ‘the most important culture hero in Māori mythology’, whose exploits and archetype provide precedents that Māori respond to in the present. The status of Maui within my own tribal boundaries is clear: ‘In accordance with the traditions and tikanga of Ngati Porou, we as People of this Land have been here since the beginning of time, or more aptly in the context of Aotearoa, since Maui fished up Te Ika-a-Maui (North Island). Maui-Tikitiki-a-Taranga is attributed with fishing up the North Island, raising it out of the depths of the sea, for successive generations of Māori to populate and cultivate.’ Maui’s waka, as Ngāti Porou uphold, is Nukutaimemeha, believed to be ‘cradled’ upon our ancestral mountain Hikurangi. However, there are other stories that recognize the waka as the South Island, with Stewart Island its anchor. These variations aside, the history remains a well-rehearsed one throughout the Māori world and in other parts of Polynesia.

text: Revitalizing Te Ika-a-Maui: Māori migration and the nation Maui-Tikitiki-A-Taranga is more than simply a ‘mythic’ hero. For many he is a prominent figure in a long family line. The whakapapa that binds Māori to our tupuna is significant to the present and future, and carries with it the ‘ultimate expression’ of who we are. Maui has been described as ‘the most important culture hero in Māori mythology’, whose exploits and archetype provide precedents that Māori respond to in the present. The status of Maui within my own tribal boundaries is clear: ‘In accordance with the traditions and tikanga of Ngati Porou, we as People of this Land have been here since the beginning of time, or more aptly in the context of Aotearoa, since Maui fished up Te Ika-a-Maui (North Island). Maui-Tikitiki-a-Taranga is attributed with fishing up the North Island, raising it out of the depths of the sea, for successive generations of Māori to populate and cultivate.’ Maui’s waka, as Ngāti Porou uphold, is Nukutaimemeha, believed to be ‘cradled’ upon our ancestral mountain Hikurangi. However, there are other stories that recognize the waka as the South Island, with Stewart Island its anchor. These variations aside, the history remains a well-rehearsed one throughout the Māori world and in other parts of Polynesia.

year: 2009