title: Examining the mid to long‐term variability in saturated hydraulic conductivity of sandy soils and its influencing factors under constant head test in the laboratory

authors: Nikghalb Ashouri, Saeed

abstract: Saturated hydraulic conductivity (Ks) is a crucial parameter that influences water flow in saturated soils, with applications in various fields such as surface water runoff, soil erosion, drainage, and solute transport. However, accurate determination of Ks is challenging due to temporal and spatial uncertainties. This study addresses the knowledge gap regarding the long‐term behavior of Ks in sandy soils with less than 10% fine particles. The research investigates the changes in Ks over a long period of constant head tests and examines the factors influencing its variation. Two sandy samples were tested using a hydraulic conductivity cell, and the hydraulic head and discharge were recorded for over 50 days. The results show a general decline in Ks throughout the test, except for brief periods of increase. At the end of both tests, there are noticeable reductions in the saturated hydraulic conductivities of the samples, with one sample being 96% and the other sample 91% less than the maximum recorded saturated hydraulic conductivity during the tests. Furthermore, the relationship between flow rate and hydraulic head gradient does not follow the expected linear correlation from Darcy's law, highlighting the complex nature of sandy soil saturated hydraulic conductivity. The investigation of soil properties in three different sections of the samples before and after the tests revealed a decrease in the percentage of fine particles and a shift in specific gravity from the bottom to the top of the sample, suggesting particle migration along the flow direction. Factors such as clogging by fine particles and pore pressure variation contribute to the changes in Ks. The findings of this research show the importance of considering changes of saturated hydraulic conductivity during constant‐head laboratory tests. Therefore, this study provides evidence for the requirement to further assess the laboratory methods for measurement of the saturated hydraulic conductivity in sandy soil mixtures.

text: Examining the mid to long‐term variability in saturated hydraulic conductivity of sandy soils and its influencing factors under constant head test in the laboratory Saturated hydraulic conductivity (Ks) is a crucial parameter that influences water flow in saturated soils, with applications in various fields such as surface water runoff, soil erosion, drainage, and solute transport. However, accurate determination of Ks is challenging due to temporal and spatial uncertainties. This study addresses the knowledge gap regarding the long‐term behavior of Ks in sandy soils with less than 10% fine particles. The research investigates the changes in Ks over a long period of constant head tests and examines the factors influencing its variation. Two sandy samples were tested using a hydraulic conductivity cell, and the hydraulic head and discharge were recorded for over 50 days. The results show a general decline in Ks throughout the test, except for brief periods of increase. At the end of both tests, there are noticeable reductions in the saturated hydraulic conductivities of the samples, with one sample being 96% and the other sample 91% less than the maximum recorded saturated hydraulic conductivity during the tests. Furthermore, the relationship between flow rate and hydraulic head gradient does not follow the expected linear correlation from Darcy's law, highlighting the complex nature of sandy soil saturated hydraulic conductivity. The investigation of soil properties in three different sections of the samples before and after the tests revealed a decrease in the percentage of fine particles and a shift in specific gravity from the bottom to the top of the sample, suggesting particle migration along the flow direction. Factors such as clogging by fine particles and pore pressure variation contribute to the changes in Ks. The findings of this research show the importance of considering changes of saturated hydraulic conductivity during constant‐head laboratory tests. Therefore, this study provides evidence for the requirement to further assess the laboratory methods for measurement of the saturated hydraulic conductivity in sandy soil mixtures.

year: 2024

title: Co-driving: Passenger actions and distractions

authors: Charlton, Samuel G.

subjects: Science & Technology

abstract: Approximately one third of car trips involve one or more passengers and yet we know little about how the presence of a passenger helps or hinders safety and efficiency. To date, research in this area has focused on the possible distractive effects of passengers. Although we know that drivers conversing on a mobile phone is distracting and unsafe, epidemiological studies suggest that driving with a passenger has a lower crash risk than driving alone. This paper describes two studies into how drivers and passengers interact during a journey; a survey regarding the most common actions of passengers and how drivers view their helpfulness, and an on-road study of driver and passenger interactions. The results indicated several areas that drivers felt passenger assistance was quite helpful, but in some cases was exhibited very rarely. The on-road study revealed some interesting gender differences in who offers driving support, and who requests it. By understanding how passengers can contribute to safer journeys we can provide that information to drivers at risk, such as those very early or late in their driving careers.

text: Co-driving: Passenger actions and distractions Approximately one third of car trips involve one or more passengers and yet we know little about how the presence of a passenger helps or hinders safety and efficiency. To date, research in this area has focused on the possible distractive effects of passengers. Although we know that drivers conversing on a mobile phone is distracting and unsafe, epidemiological studies suggest that driving with a passenger has a lower crash risk than driving alone. This paper describes two studies into how drivers and passengers interact during a journey; a survey regarding the most common actions of passengers and how drivers view their helpfulness, and an on-road study of driver and passenger interactions. The results indicated several areas that drivers felt passenger assistance was quite helpful, but in some cases was exhibited very rarely. The on-road study revealed some interesting gender differences in who offers driving support, and who requests it. By understanding how passengers can contribute to safer journeys we can provide that information to drivers at risk, such as those very early or late in their driving careers.

year: 2020

title: The Buried Village, New Zealand - an example of dark tourism?

authors: Ryan, Chris

subjects: dark tourism

abstract: In 1886, the explosion of Mount Tarawera resulted in the loss of 150 lives and the burial of the village of Te Wairoa, the base from which tourists had visited the Pink and White Terraces, a silicone-stained natural formation then advertised as one of the natural wonders of the world. Since 1931, the buried site has itself been a tourist attraction and Smith and Croy have argued that it serves as an example of “dark tourism”. This paper uses a different methodology to argue that Lennon and Foley's original definition of dark tourism is precise, that the buried village of Te Wairoa does not meet that specification, but does support the model suggested by Sharpley, that the site's characteristics are those of grey tourism supply. However, the findings derived from a sample of over 600 respondents indicate that sites are complex packages of potential experiences, and are potentially multi-faceted in terms of the experiences they offer. It is also suggested that cultural components might play a role in the experience of what is “dark” about a site.

text: The Buried Village, New Zealand - an example of dark tourism? In 1886, the explosion of Mount Tarawera resulted in the loss of 150 lives and the burial of the village of Te Wairoa, the base from which tourists had visited the Pink and White Terraces, a silicone-stained natural formation then advertised as one of the natural wonders of the world. Since 1931, the buried site has itself been a tourist attraction and Smith and Croy have argued that it serves as an example of “dark tourism”. This paper uses a different methodology to argue that Lennon and Foley's original definition of dark tourism is precise, that the buried village of Te Wairoa does not meet that specification, but does support the model suggested by Sharpley, that the site's characteristics are those of grey tourism supply. However, the findings derived from a sample of over 600 respondents indicate that sites are complex packages of potential experiences, and are potentially multi-faceted in terms of the experiences they offer. It is also suggested that cultural components might play a role in the experience of what is “dark” about a site.

year: 2006