3,090 research outputs found
Flood dynamics derived from video remote sensing
Flooding is by far the most pervasive natural hazard, with the human impacts of floods expected to worsen in the coming decades due to climate change. Hydraulic models are a key tool for understanding flood dynamics and play a pivotal role in unravelling the processes that occur during a flood event, including inundation flow patterns and velocities. In the realm of river basin dynamics, video remote sensing is emerging as a transformative tool that can offer insights into flow dynamics and thus, together with other remotely sensed data, has the potential to be deployed to estimate discharge. Moreover, the integration of video remote sensing data with hydraulic models offers a pivotal opportunity to enhance the predictive capacity of these models.
Hydraulic models are traditionally built with accurate terrain, flow and bathymetric data and are often calibrated and validated using observed data to obtain meaningful and actionable model predictions. Data for accurately calibrating and validating hydraulic models are not always available, leaving the assessment of the predictive capabilities of some models deployed in flood risk management in question. Recent advances in remote sensing have heralded the availability of vast video datasets of high resolution. The parallel evolution of computing capabilities, coupled with advancements in artificial intelligence are enabling the processing of data at unprecedented scales and complexities, allowing us to glean meaningful insights into datasets that can be integrated with hydraulic models. The aims of the research presented in this thesis were twofold. The first aim was to evaluate and explore the potential applications of video from air- and space-borne platforms to comprehensively calibrate and validate two-dimensional hydraulic models. The second aim was to estimate river discharge using satellite video combined with high resolution topographic data. In the first of three empirical chapters, non-intrusive image velocimetry techniques were employed to estimate river surface velocities in a rural catchment. For the first time, a 2D hydraulicvmodel was fully calibrated and validated using velocities derived from Unpiloted Aerial Vehicle (UAV) image velocimetry approaches. This highlighted the value of these data in mitigating the limitations associated with traditional data sources used in parameterizing two-dimensional hydraulic models. This finding inspired the subsequent chapter where river surface velocities, derived using Large Scale Particle Image Velocimetry (LSPIV), and flood extents, derived using deep neural network-based segmentation, were extracted from satellite video and used to rigorously assess the skill of a two-dimensional hydraulic model. Harnessing the ability of deep neural networks to learn complex features and deliver accurate and contextually informed flood segmentation, the potential value of satellite video for validating two dimensional hydraulic model simulations is exhibited. In the final empirical chapter, the convergence of satellite video imagery and high-resolution topographical data bridges the gap between visual observations and quantitative measurements by enabling the direct extraction of velocities from video imagery, which is used to estimate river discharge. Overall, this thesis demonstrates the significant potential of emerging video-based remote sensing datasets and offers approaches for integrating these data into hydraulic modelling and discharge estimation practice. The incorporation of LSPIV techniques into flood modelling workflows signifies a methodological progression, especially in areas lacking robust data collection infrastructure. Satellite video remote sensing heralds a major step forward in our ability to observe river dynamics in real time, with potentially significant implications in the domain of flood modelling science
Producing context specific land cover and land use maps of human-modified tropical forest landscapes for infectious disease applications
Satellite-based land cover mapping plays an important role in understanding changes in ecosystems and biodiversity. There are global land cover products available, however for region specific studies of drivers of infectious disease patterns, these can lack the spatial and thematic detail or accuracy required to capture key ecological processes. To overcome this, we produced our own Landsat derived 30 m maps for three districts in India's Western Ghats (Wayanad, Shivamogga and Sindhudurg). The maps locate natural vegetation types, plantation types, agricultural areas, water bodies and settlements in the landscape, all relevant to functional resource use of species involved in infectious disease dynamics. The maps represent the mode of 50 classification iterations and include a spatial measure of class stability derived from these iterations. Overall accuracies for Wayanad, Shivamogga and Sindhudurg are 94.7 % (SE 1.2 %), 88.9 % (SE 1.2 %) and 88.8 % (SE 2 %) respectively. Class classification stability was high across all three districts and the individual classes that matter for defining key interfaces between human habitation, forests, crop, and plantation cultivation, were generally well separated. A comparison with the 300 m global ESA CCI land cover map highlights lower ESA CCI class accuracies and the importance of increased spatial resolution when dealing with complex landscape mosaics. A comparison with the 30 m Global Forest Change product reveals an accurate mapping of forest loss and different dynamics between districts (i.e., Forests lost to Built-up versus Forests lost to Plantations), demonstrating an interesting complementarity between our maps and the % tree cover Global Forest Change product. When studying infectious disease responses to land use change in tropical forest ecosystems, we recommend using bespoke land cover/use classifications reflecting functional resource use by relevant vectors, reservoirs, and people. Alternatively, global products should be carefully validated with ground reference points representing locally relevant habitats. [Abstract copyright: Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.
FARMS, FLEA MARKETS, AND FACEBOOK: PERSPECTIVES ON REGULATION, BIOSECURITY, AND INFECTIOUS DISEASE RISK AMONG PRODUCERS AND POULTRY VENDORS IN MULTIPLE SETTINGS
Flea markets, trade days, and social media groups are used by backyard farmers to buy and sell poultry and provide a means of connection between members of these communities. Poultry are common reservoirs of zoonotic diseases; proper biosecurity practices are critical in preventing outbreaks of infectious disease among flocks and in humans. However, biosecurity regulations in these informal marketplaces range from marginal to nonexistent, and thus an exploration of current knowledge, biosecurity practices, and perceptions on regulation can be useful in developing policy and interventions to ensure good biosecurity and thereby protect animal and public health.
This dissertation represents an exploration of the perceptions of regulation among producers and backyard poultry farmers, as well as a survey of current infectious disease and biosecurity knowledge and practices as they relate to selling poultry at informal markets. Formative qualitative research with 31 members of the agricultural provides insight into perceptions on regulation and the role of government in protecting human and animal health, demonstrating perceived sense of overregulation, distrust for the motives of policymakers, and a desire to be included in decision making.
These findings were extended through two studies that assessed the knowledge, attitudes, practices, and risk perceptions of poultry sellers at informal marketplaces. We conducted surveys (n=31) and supplemental interviews (n=5) with poultry sellers at flea markets in Texas, and then adapted the survey to backyard flock owners on social media poultry groups (n=83). In both groups, knowledge of infectious disease was moderate, attitudes were positive toward biosecurity and were negative toward government; risk perceptions for infectious diseases were low; and biosecurity behaviors were moderately good, except for key practices such as vaccination and reporting notifiable diseases.
This research represents a foundational step towards improved biosecurity in informal poultry marketplaces; the findings suggest that interventions might be more successful through 1) a combination of education, risk communication, and mentoring programs to address knowledge gaps in infectious disease and biosecurity, and 2) an appreciation of the lived experience of poultry vendors. In these ways, informal marketplaces can become safer venues for poultry sales that prioritize and protect animal and human health
Increasing Sustainable Bivalve Aquaculture Productivity Using Remote Non-Invasive Sensing and Upweller Technologies
The work and findings described by this thesis aim to develop technologies and approaches relevant to bivalve aquaculture, focusing on non invasive sensing to monitor bivalve shellfish, primarily the Pacific oyster (Magallana gigas). Following the introduction, Chapter 2 presents an overview of the Non Invasive Oyster Sensor (NOSy), a sensor developed at the University of Essex that records bivalve openness (gape). NOSy was conceived to automatically detect spawning as an aid to oyster growers and has proved useful in field and laboratory, work which underpins three chapters in this thesis. NOSy remains under development, and has potential for use in aquaculture, monitoring and research.
Chapter 3 assesses the role of salinity in driving estuarine oyster behaviour. We replicated an estuarine tidal salinity cycle and recorded the gape of oysters exposed to it. Behaviours during the experiment did not resemble those in the estuary, suggesting that salinity alone does not drive estuarine oyster behaviour. We also discuss the challenges of controlling salinity in a laboratory, and suggest it is an under-studied area.
Chapter 4 discusses land based systems for young oyster growing. Land-based systems have the potential to improve growth, condition and survival while reducing labour and maintenance costs. We trialled a system over three summers, with promising results. Reduction of localised densities improved growth rate and uniformity. Cost forecasts suggest that adoption of land based growing systems could result in substantial savings.
Chapter 5 presents gaping records from an area where Blue mussels (Mytilus edulis) have become non harvestable in recent years due to contamination. We used NOSy to assess gaping patterns of the mussel population to evaluate how their behaviours affect their vulnerability to contamination. Mussels in the bay closed over low tide as a response to extremely low salinity, inferring protection from contamination by limiting the mussel’s exposure
Air Quality Research Using Remote Sensing
Air pollution is a worldwide environmental hazard that poses serious consequences not only for human health and the climate but also for agriculture, ecosystems, and cultural heritage, among other factors. According to the WHO, there are 8 million premature deaths every year as a result of exposure to ambient air pollution. In addition, more than 90% of the world’s population live in areas where the air quality is poor, exceeding the recommended limits. On the other hand, air pollution and the climate co-influence one another through complex physicochemical interactions in the atmosphere that alter the Earth’s energy balance and have implications for climate change and the air quality. It is important to measure specific atmospheric parameters and pollutant compound concentrations, monitor their variations, and analyze different scenarios with the aim of assessing the air pollution levels and developing early warning and forecast systems as a means of improving the air quality and safeguarding public health. Such measures can also form part of efforts to achieve a reduction in the number of air pollution casualties and mitigate climate change phenomena. This book contains contributions focusing on remote sensing techniques for evaluating air quality, including the use of in situ data, modeling approaches, and the synthesis of different instrumentations and techniques. The papers published in this book highlight the importance and relevance of air quality studies and the potential of remote sensing, particularly that conducted from Earth observation platforms, to shed light on this topic
Effects of municipal smoke-free ordinances on secondhand smoke exposure in the Republic of Korea
ObjectiveTo reduce premature deaths due to secondhand smoke (SHS) exposure among non-smokers, the Republic of Korea (ROK) adopted changes to the National Health Promotion Act, which allowed local governments to enact municipal ordinances to strengthen their authority to designate smoke-free areas and levy penalty fines. In this study, we examined national trends in SHS exposure after the introduction of these municipal ordinances at the city level in 2010.MethodsWe used interrupted time series analysis to assess whether the trends of SHS exposure in the workplace and at home, and the primary cigarette smoking rate changed following the policy adjustment in the national legislation in ROK. Population-standardized data for selected variables were retrieved from a nationally representative survey dataset and used to study the policy action’s effectiveness.ResultsFollowing the change in the legislation, SHS exposure in the workplace reversed course from an increasing (18% per year) trend prior to the introduction of these smoke-free ordinances to a decreasing (−10% per year) trend after adoption and enforcement of these laws (β2 = 0.18, p-value = 0.07; β3 = −0.10, p-value = 0.02). SHS exposure at home (β2 = 0.10, p-value = 0.09; β3 = −0.03, p-value = 0.14) and the primary cigarette smoking rate (β2 = 0.03, p-value = 0.10; β3 = 0.008, p-value = 0.15) showed no significant changes in the sampled period. Although analyses stratified by sex showed that the allowance of municipal ordinances resulted in reduced SHS exposure in the workplace for both males and females, they did not affect the primary cigarette smoking rate as much, especially among females.ConclusionStrengthening the role of local governments by giving them the authority to enact and enforce penalties on SHS exposure violation helped ROK to reduce SHS exposure in the workplace. However, smoking behaviors and related activities seemed to shift to less restrictive areas such as on the streets and in apartment hallways, negating some of the effects due to these ordinances. Future studies should investigate how smoke-free policies beyond public places can further reduce the SHS exposure in ROK
Climate change: strategies for mitigation and adaptation
The sustainability of life on Earth is under increasing threat due to human-induced climate change. This perilous change in the Earth's climate is caused by increases in carbon dioxide and other greenhouse gases in the atmosphere, primarily due to emissions associated with burning fossil fuels. Over the next two to three decades, the effects of climate change, such as heatwaves, wildfires, droughts, storms, and floods, are expected to worsen, posing greater risks to human health and global stability. These trends call for the implementation of mitigation and adaptation strategies. Pollution and environmental degradation exacerbate existing problems and make people and nature more susceptible to the effects of climate change. In this review, we examine the current state of global climate change from different perspectives. We summarize evidence of climate change in Earth’s spheres, discuss emission pathways and drivers of climate change, and analyze the impact of climate change on environmental and human health. We also explore strategies for climate change mitigation and adaptation and highlight key challenges for reversing and adapting to global climate change
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