Improvements in vortex flow control design to increase sewer network flood resistance

Copyright © 2013 IWA7th International Conference on Sewer Processes and Networks (SPN7), Sheffield, UK, 28-30 August 2013Flow controls are used within the water industry to manage the flow through sewer networks by attenuating flows at convenient or critical locations. Many sewer networks, regardless whether the systems have a flow control installed, are predicted to become stressed in the future due to the effects of climate change, population growth and urbanisation. This issue is compounded by the age of the Britain’s sewerage infrastructure as well as the cost and difficulty of replacing and upgrading the infrastructure. Statutory ‘Catchment Flood Management Plans’ have been introduced within the United Kingdom to tackle this issue by better understanding the flow path of flood water on a catchment scale. This paper discusses a method to maximise the use of the current sewerage infrastructure by installing flow controls, meaning a greater volume of the sewer network can be used for stormwater storage. This paper continues by describing a method of increasing a sewer network’s flood resistance by using vortex flow controls with a lower design flow-rate compared to an orifice plate. This paper then concludes by describing three case studies demonstrating the use vortex flow controls when retrofitting sewer networks as well as the impact of implementing the retrofit design method.EPSRCSTREAM IDCHydro Internationa

Computational fluid dynamics as a tool for urban drainage system analysis: a review of applications and best practice

Computational Fluid Dynamics (CFD) can be applied to gain insights into most fluid processes and associated phenomena and so presents potential to add value in the analysis of urban drainage systems. This paper presents a review of CFD studies carried out in this field, with the objective of developing an appreciation of how and where it can be applied. Existing work has tended to focus around the analysis of four types of urban drainage structure, including Combined Sewer Overflows (CSOs), storage and attenuation systems, stormwater sediment interceptors and sewerage conveyance structures. Within the respective studies, the prediction of flowfields, particulate behaviour, water surface profiles and Residence Time Distributions (RTDs) are found to form the main focus, and as such, these are considered in most detail in the paper. It is concluded that CFD presents a number of opportunities in urban drainage system analysis, and that the scope of this opportunity will further develop as both computational hardware and software resources become more advanced

Region-wide synchrony and traveling waves of dengue across eight countries in Southeast Asia [plus Supporting information]

Dengue is a mosquito-transmitted virus infection that causes epidemics of febrile illness and hemorrhagic fever across the tropics and subtropics worldwide. Annual epidemics are commonly observed, but there is substantial spatiotemporal heterogeneity in intensity. A better understanding of this heterogeneity in dengue transmission could lead to improved epidemic prediction and disease control. Time series decomposition methods enable the isolation and study of temporal epidemic dynamics with a specific periodicity (e.g., annual cycles related to climatic drivers and multiannual cycles caused by dynamics in population immunity). We collected and analyzed up to 18 y of monthly dengue surveillance reports on a total of 3.5 million reported dengue cases from 273 provinces in eight countries in Southeast Asia, covering similar to 10(7) km(2). We detected strong patterns of synchronous dengue transmission across the entire region, most markedly during a period of high incidence in 1997-1998, which was followed by a period of extremely low incidence in 2001-2002. This synchrony in dengue incidence coincided with elevated temperatures throughout the region in 1997-1998 and the strongest El NiNo episode of the century. Multiannual dengue cycles (2-5 y) were highly coherent with the Oceanic NiNo Index, and synchrony of these cycles increased with temperature. We also detected localized traveling waves of multiannual dengue epidemic cycles in Thailand, Laos, and the Philippines that were dependent on temperature. This study reveals forcing mechanisms that drive synchronization of dengue epidemics on a continental scale across Southeast Asia

Region-wide synchrony and traveling waves of dengue across eight countries in Southeast Asia [plus Supporting information]

Dengue is a mosquito-transmitted virus infection that causes epidemics of febrile illness and hemorrhagic fever across the tropics and subtropics worldwide. Annual epidemics are commonly observed, but there is substantial spatiotemporal heterogeneity in intensity. A better understanding of this heterogeneity in dengue transmission could lead to improved epidemic prediction and disease control. Time series decomposition methods enable the isolation and study of temporal epidemic dynamics with a specific periodicity (e.g., annual cycles related to climatic drivers and multiannual cycles caused by dynamics in population immunity). We collected and analyzed up to 18 y of monthly dengue surveillance reports on a total of 3.5 million reported dengue cases from 273 provinces in eight countries in Southeast Asia, covering similar to 10(7) km(2). We detected strong patterns of synchronous dengue transmission across the entire region, most markedly during a period of high incidence in 1997-1998, which was followed by a period of extremely low incidence in 2001-2002. This synchrony in dengue incidence coincided with elevated temperatures throughout the region in 1997-1998 and the strongest El NiNo episode of the century. Multiannual dengue cycles (2-5 y) were highly coherent with the Oceanic NiNo Index, and synchrony of these cycles increased with temperature. We also detected localized traveling waves of multiannual dengue epidemic cycles in Thailand, Laos, and the Philippines that were dependent on temperature. This study reveals forcing mechanisms that drive synchronization of dengue epidemics on a continental scale across Southeast Asia

An exploration of nutrition and eating disabilities in relation to quality of life at 6 months post-stroke

Quality of life (QoL) is increasingly recognised as an important healthcare outcome, especially for those living with enduring disability. Stroke is a major source of long-term disablement and many aspects of life after stroke have been explored. Little attention has been paid to nutritional issues despite the cultural and hedonistic importance of food and eating, and the deleterious effects of malnutrition. The present study employed an epidemiological survey to investigate the contribution of dietary and nutritional factors in relation to QoL after stroke. The participants were 206 survivors of a cohort of acute stroke patients consecutively admitted to a National Health Service trust hospital in South London, UK, between March 1998 and April 1999. They were interviewed in their homes at 6 months post-stroke. Cognitively or communication-impaired patients were precluded from interview except where a live-in carer participated as a proxy (n = 10). The participation rate for those who were eligible and could be contacted was 206 out of 218 (94%). Participants were assessed using standardised, validated tools for functional abilities in activities of daily living and eating, cognition and mood state, social support and economic indices, nutritional status, dietary intake, and QoL. Overall group scores demonstrated relatively minor degrees of physical disablement; exclusion of those with limited cognition and communication precluded assessment of a small subgroup with greater disablement at hospital discharge. Nonetheless, the overall assessment results were not dissimilar to other reported groups. Indices of poor nutritional status and substantial dietary inadequacy were revealed, linked with reduced appetite and depression. Multiple regression analyses revealed the dominant impact of mood state in relation to QoL scores; additional significant effects were identified for social support, eating-related disabilities and age. The effects of mood and social support are well-recognised, whilst nutrition-related effects have previously received little attention. Intervention in these areas might achieve improvements in survivors' perceived QoL