title: Geomorphology and flooding shape fish distribution in a large-scale temperate floodplain

authors: Górski, K.

subjects: Volga River

abstract: Natural river-floodplain systems are characterized by their dynamic hydrology and diverse geomorphology resulting in a wide range of habitats that support high fish diversity and production. Various factors (e.g. hydrological dynamics, water quality, and biotic processes) have been proposed to explain fish distribution in large river floodplains, but it is still widely acknowledged that the mechanisms involved may vary in diverse floodplain systems and that they are not fully understood. To determine how flooding dynamics and floodplain geomorphology influence fish species distributions across the Volga-Akhtuba floodplain, Russian Federation, we examined the distributions of eight species with respect to variables reflecting floodplain hydrology and geomorphology. On the basis of fish catches in 40 floodplain water bodies at the end of summer in 2006–2008, we found that frequency of occurrence of most fish species remained stable along the time. The distribution of fish species was strongly influenced by the size and shape of water bodies as well as flood extent. Therefore, the long-term flood variability that drives the geomorphic heterogeneity of the floodplain creates suitable habitats across ranges of fish flow guilds (rheophilic, eurytopic, and limnophilic), resulting in high diversity of the floodplain ichthyofauna. We conclude that this diverse habitat availability is a highly significant factor influencing fish distribution in the Volga-Akhtuba floodplain.

text: Geomorphology and flooding shape fish distribution in a large-scale temperate floodplain Natural river-floodplain systems are characterized by their dynamic hydrology and diverse geomorphology resulting in a wide range of habitats that support high fish diversity and production. Various factors (e.g. hydrological dynamics, water quality, and biotic processes) have been proposed to explain fish distribution in large river floodplains, but it is still widely acknowledged that the mechanisms involved may vary in diverse floodplain systems and that they are not fully understood. To determine how flooding dynamics and floodplain geomorphology influence fish species distributions across the Volga-Akhtuba floodplain, Russian Federation, we examined the distributions of eight species with respect to variables reflecting floodplain hydrology and geomorphology. On the basis of fish catches in 40 floodplain water bodies at the end of summer in 2006–2008, we found that frequency of occurrence of most fish species remained stable along the time. The distribution of fish species was strongly influenced by the size and shape of water bodies as well as flood extent. Therefore, the long-term flood variability that drives the geomorphic heterogeneity of the floodplain creates suitable habitats across ranges of fish flow guilds (rheophilic, eurytopic, and limnophilic), resulting in high diversity of the floodplain ichthyofauna. We conclude that this diverse habitat availability is a highly significant factor influencing fish distribution in the Volga-Akhtuba floodplain.

year: 2012

title: Web crippling behaviour of cold-formed steel channel sections having elongated edge-stiffened web holes under interior-two-flange loading condition

authors: Wang, Wei

subjects: cold-formed steel

abstract: In the past decade, cold-formed steel (CFS) channel sections having circular edge-stiffened web holes have been developed in New Zealand. Such edge-stiffened holes increase the strength of the CFS channel sections, compared to an equivalent section having unstiffened holes, while still allowing full service integration. In the case of web crippling, previous research has found that use of edge-stiffened holes almost results in the same strength of an equivalent channel-section having a plain web. Such circular edge-stiffened web holes can now be extended to elongated edge-stiffened web holes. However, for such elongated holes, no experimental tests have been reported in the literature. In this paper, a numerical investigation was carried out, and non-linear finite element (FE) analyses were used to investigate the web crippling behaviour of CFS channel sections having edge-stiffened web holes under the interior-two-flange (ITF) loading condition. The cases of both flange fastened and flange unfastened were considered. The FE models were validated against test results of sections having circular edge-stiffened web holes; good agreement in terms of the load–displacement curves and deformed shapes was shown. Using the validated FE models, a parametric study was carried out on CFS channel sections having elongated un-stiffened and edge-stiffened web holes, comprising 1,227 finite element analyses (FEA) results. Compared to sections having a plain web, for the case of an elongated opening, without any edge-stiffener, having an aspect ratio of two and three, the average reduction in web crippling strength was 39% and 49%, respectively. However, for an edge-stiffened hole, the reduction in the web crippling strength was reduced to only 2% and 16%, respectively. Finally, the design equations in the form of the web crippling reduction factor (Rp) and the equations based on the direct strength method (DSM) for CFS sections with elongated web holes were proposed.

text: Web crippling behaviour of cold-formed steel channel sections having elongated edge-stiffened web holes under interior-two-flange loading condition In the past decade, cold-formed steel (CFS) channel sections having circular edge-stiffened web holes have been developed in New Zealand. Such edge-stiffened holes increase the strength of the CFS channel sections, compared to an equivalent section having unstiffened holes, while still allowing full service integration. In the case of web crippling, previous research has found that use of edge-stiffened holes almost results in the same strength of an equivalent channel-section having a plain web. Such circular edge-stiffened web holes can now be extended to elongated edge-stiffened web holes. However, for such elongated holes, no experimental tests have been reported in the literature. In this paper, a numerical investigation was carried out, and non-linear finite element (FE) analyses were used to investigate the web crippling behaviour of CFS channel sections having edge-stiffened web holes under the interior-two-flange (ITF) loading condition. The cases of both flange fastened and flange unfastened were considered. The FE models were validated against test results of sections having circular edge-stiffened web holes; good agreement in terms of the load–displacement curves and deformed shapes was shown. Using the validated FE models, a parametric study was carried out on CFS channel sections having elongated un-stiffened and edge-stiffened web holes, comprising 1,227 finite element analyses (FEA) results. Compared to sections having a plain web, for the case of an elongated opening, without any edge-stiffener, having an aspect ratio of two and three, the average reduction in web crippling strength was 39% and 49%, respectively. However, for an edge-stiffened hole, the reduction in the web crippling strength was reduced to only 2% and 16%, respectively. Finally, the design equations in the form of the web crippling reduction factor (Rp) and the equations based on the direct strength method (DSM) for CFS sections with elongated web holes were proposed.

year: 2023-11-01

title: Social deprivation in New Zealand

authors: Harcourt, Brian James

subjects: Deprivation

abstract: The purpose of the thesis was to better understand the phenomenon of social deprivation, world-wide and in particular in New Zealand. Social deprivation has been defined in many ways with multiple surrogates used to ‘measure’ its prevalence. The aim of this research was to provide examples of the lived experiences of social deprivation.

Social constructivist and interpretive lenses were used to portray the voices of those living in deprivation, as well as those people tasked to assist them. A narrative case study approach was employed with participants from Whānau Ora. This social and health initiative offered a holistic approach to assistance in contrast to the usual State agencies operating in a silo fashion, with separate agencies providing for different aspects of social deprivation such as housing, employment, mental health and other services. The approach of Whānau Ora is to support clients’ needs holistically and encourage people to develop their own plans for self- improvement. Navigators help people develop their plans and assist in their interactions with the various State agencies whose services they require. This approach allowed a better understanding of ways to overcome people’s feelings of powerlessness and desperation.

The findings from the study lead to suggestions for the application of evidence-based, complementary, integrated assistance programmes rather than having segregated public service agencies acting independently. The recommendations are simple yet require profound changes in public service operations when attempting to ameliorate or prevent social deprivation among citizens.

text: Social deprivation in New Zealand The purpose of the thesis was to better understand the phenomenon of social deprivation, world-wide and in particular in New Zealand. Social deprivation has been defined in many ways with multiple surrogates used to ‘measure’ its prevalence. The aim of this research was to provide examples of the lived experiences of social deprivation.

Social constructivist and interpretive lenses were used to portray the voices of those living in deprivation, as well as those people tasked to assist them. A narrative case study approach was employed with participants from Whānau Ora. This social and health initiative offered a holistic approach to assistance in contrast to the usual State agencies operating in a silo fashion, with separate agencies providing for different aspects of social deprivation such as housing, employment, mental health and other services. The approach of Whānau Ora is to support clients’ needs holistically and encourage people to develop their own plans for self- improvement. Navigators help people develop their plans and assist in their interactions with the various State agencies whose services they require. This approach allowed a better understanding of ways to overcome people’s feelings of powerlessness and desperation.

The findings from the study lead to suggestions for the application of evidence-based, complementary, integrated assistance programmes rather than having segregated public service agencies acting independently. The recommendations are simple yet require profound changes in public service operations when attempting to ameliorate or prevent social deprivation among citizens.

year: 2019