Dissertations / Theses on the topic 'Risk assessment – Vietnam'

Vietnamese farmers are at high risk of pesticide exposure due to usage of pack-back sprays for application of pesticides with their rice crops. Chlorpyirifos has been the most common organophosphate registered for agricultural use in Vietnam, however the health risk due to the use of this compound by rice farmers has not been evaluated. The primary objective of this study was to evaluate the health risk of chlorpyrifos exposure to rice farmers, using a probabilistic approach, with a secondary objective of developing safety strategies for pesticide risk reduction, using qualitative needs assessment methods used for evaluating health promotion programs. Farmer exposure to chlorpyrifos from pesticide application was measured by biological monitoring. Urine samples were collected from farmers (18) over pesticide spraying application time and analysed for 3,5,6-trichloropyridinol (TCP), the major urinary metabolite of chlorpyrifos, using an enzymatic pre-treatment before extraction followed by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Absorbed Daily Doses (ADD) of chlorpyrifos for farmers was then estimated from urinary TCP levels, expressed as μg/g creatinine. The exposure doses, comprising baseline exposure dose (ADDB), post-application exposure dose (ADDA), and lifetime average daily exposure dose (LADDE) were calculated. The baseline exposure dose (ADDB) ranged from 0.03 to 1.98 μg/kg/d with a mean of 0.24 μg/kg/d. The post-application exposure dose (ADDA) ranged from 0.35 to 94 μg/kg/d with a mean of 19.4 μg/kg/d which is approximately 80 times higher than the mean values of ADDB (0.24 μg/kg/d). The lifetime average daily dose (LADDE) ranged from 0.01 to 1.7 μg/kg/d with a mean of 0.3 μg/kg/d. Multivariate regression analysis indicated that personal protective equipment reflected by percentage of body coverage, amount of chlorpyrifos used and length of application made major contributions to ADDA. However, the best regression model for the relationship between ADDA and exposure factors was observed with two independent variables comprising body coverage and amount of chlorpyrifos used.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

During the US – Vietnam War (1961 – 1972), Vietnam was subjected to widespread spraying of the chemical herbicide that is also called Agent Orange containing the most toxic dioxin congener, of 2,3,7,8-Tetrachlorodibenzo(p)dioxin (2,3,7,8-TCDD). A Luoi district belongs to Thua Thien- Hue province, located in the western part of the North Central coast region of Vietnam. During the Ranch Hand campaign (1965 -1970), A Luoi was heavily sprayed with this herbicide. In order to assess potential human health risks for people due to 2,3,7,8-TCDD exposure from contaminated soil, more than 50 soil samples were collected in A Luoi district area in 2013 and 2014 to determine dioxin concentrations by HRGC/HRMS. Human health risk assessment was applied using internationally recognized approaches. Hazard Quotient (HQ) values, assuming 2,3,7,8-TCDD to be a threshold contaminant, were calculated to be 13.2 and 6.1; and Incremental Lifetime Cancer Risk (ILCTR) values, assuming 2,3,7,8-TCDD to be carcinogenic non threshold, were 0.00314 and 0.00627 for adults and children, respectively. These results from exposures in A Luoi show risk values, which are several hundred times higher than acceptable TRVs. The results of this study indicate that, although the war ended nearly 50 years ago, communities living in A Luoi are still at risk of residual dioxin exposure from soils contaminated. Therefore, risk management and mitigation measures are needed, including targeted soil remediation and provision of improved medical and health systems. To our knowledge, this is the first human health risk assessment (HRRA) study in areas sprayed by herbicides during the war in Vietnam.
Trong thời kỳ chiến tranh giữa Mỹ và Việt Nam (1961 - 1972), Việt Nam phải hứng chịu một lượng lớn chất diệt cỏ còn gọi là chất Da cam, trong đó chứa chất hóa học siêu độc 2,3,7,8- Tetrachlorodibenzo (p) dioxin (2,3,7,8-TCDD). Huyện A Lưới thuộc tỉnh Thừa Thiên-Huế, nằm ở phía tây của vùng duyên hải Bắc Trung Bộ Việt Nam. Trong chiến dịch Ranch Hand (1965-1970), huyện A Lưới đã nhiều lần bị phun rải chất diệt cỏ này. Trong 2 năm 2013 và 2014, hơn 50 mẫu đất và thực phẩm đã được thu thập ở khu vực huyện A Lưới và phân tích xác định nồng độ dioxin nhằm đánh giá rủi ro về sức khỏe đối với người dân sống trong vùng bị phun rải chất diệt cỏ trong chiến tranh. Nếu giả định chất 2,3,7,8-TCDD là chất độc có ngưỡng, giá trị HQ (hệ số rủi ro) tính được là 13,2 và 6,1; và nếu giả định 2,3,7,8-TCDD là chất độc gây ung thư không ngưỡng, các giá trị ILCR (nguy cơ ung thư tăng dần suốt đời) tìm được là 0,00314 và 0,00627, tương ứng đối với người lớn và trẻ em sống ở A Lưới. Khi so sánh với các giá trị TRVs (rủi ro chấp nhận được) cho thấy các giá trị rủi ro ở A Lưới cao hơn vài trăm lần. Từ kết quả này chỉ ra mặc dù chiến tranh đã kết thúc gần 50 năm trước, cộng đồng ở A Lưới vẫn có nguy cơ phơi nhiễm dioxin. Cần thiết phải sớm có các biện pháp quản lý rủi ro và giảm thiểu phơi nhiễm dioxin cho người dân, bao gồm việc xử lý đất và cung cấp các hệ thống bảo vệ môi trường, y tế và cải thiện sức khỏe. Đây là bài báo đầu tiên về đánh giá rủi ro sức khỏe cộng đồng dân cư do phơi nhiễm dioxin ở những vùng bị phun rải chất diệt cỏ trong chiến tranh.

Electrical resistivity imaging (ERI) and groundwater solute transport modelling are developed for recovery of the hydrogeological architecture of coastal margins. ERI acquisition and processing parameters, along with the influence of hydraulic anisotropy and heterogeneity in karstic aquifers, are explored with examples selected along more than 100 km of coastline proximal to Perth Western Australia. The methods will contribute to accurate predictive groundwater modelling and sustainable management of high-quality coastal aquifers worldwide.

Nowadays, one of the urgent issues in the management of river basin resources as land degradation, especially soil erosion risk occurs due to complex factors of climate, cultivation practices of human and impacting of the operation of socio-economic development taking place in the basin. Soil erosion has been considered as the primary cause of soil degradation since soil erosion leads to the loss of topsoil and soil organic matters, which are essential for the growing of plants. Ta Trach river watershed, is a mountainous basin lying to the West - South of Thua Thien Hue province, having complex terrain. The result of this study showed that the amount of sediment yield accounts for high percentage. The average annual sedimentation is 41.60 tones per hectometer in the period of 2005 to 2010, soil erosion were classified by 5 levels. In which, the less deleterious erosion level still occupies high percentage with more than 55 % of watershed area. The main area of less deleterious soil erosion was located at high topography and high slope. The area of deleterious soil erosion occupies percentage lower than 22.63% of the entire basin, but it is also a warning sign to the extent of land degradation taking place in the basin if the erosion rate increases in the future
Ngày nay, một trong những vấn đề cấp bách trong quản lý tài nguyên lưu vực sông là sự thoái hóa đất và đặc biệt là nguy cơ xói mòn đất xảy ra do yếu tố khí hậu phức tạp, phương thức canh tác của con người và tác động của những hoạt động phát triển kinh tế - xã hội đang diễn ra ở lưu vực. Lưu vực sông Tả Trạch là một lưu vực miền núi nằm về phía Tây - Nam của tỉnh Thừa Thiên Huế, có địa hình khá phức tạp. Mục tiêu của nghiên cứu này là ứng dụng công cụ SWAT để mô phỏng xói mòn đất ở lưu vực sông Tả Trạch thuộc tỉnh Thừa Thiên Huế từ năm 2005 đến năm 2010. Kết quả của nghiên cứu cho thấy lượng đất bồi lắng ở lưu vực chiếm tỷ lệ cao, trung bình mỗi năm bồi lắng 41.60 tấn/ha trong giai đoạn 2005 đến 2010, mức độ xói mòn được phân cấp thành 5 cấp xói mòn. Trong đó, mức độ xói mòn ít nguy hại chiếm ở tỷ lệ cao hơn 55 % diện tích lưu vực, chủ yếu phân bố ở những khu vực có địa hình cao, độ dốc lớn. Diện tích xói mòn nguy hại chiếm tỷ lệ thấp hơn 22,63% diện tích toàn lưu vực nhưng đây cũng là một dấu hiệu báo động cho mức độ thoái hóa đất diễn ra ở lưu vực trong tương lai nếu mức xói mòn này tăng lên

This study assessed environmental health risk from dioxin in foods and sustainability of risk reduction programs at two heavily contaminated former military sites in Vietnam. The study involved 1000 household surveys, analysis of food samples and in-depth discussions with residents and officials. The findings indicate that more than 40 years after the war, local residents still experience high exposure to dioxin if they consume local high risk foods. Public health intervention programs were rated moderately to well sustained. Internal migration, and lack of clear, official guidance and sensitivity regarding dioxin issues were the main challenges for sustainability of prevention programs.

Nowadays, one of the urgent issues in the management of river basin resources as land degradation, especially soil erosion risk occurs due to complex factors of climate, cultivation practices of human and impacting of the operation of socio-economic development taking place in the basin. Soil erosion has been considered as the primary cause of soil degradation since soil erosion leads to the loss of topsoil and soil organic matters, which are essential for the growing of plants. Ta Trach river watershed, is a mountainous basin lying to the West - South of Thua Thien Hue province, having complex terrain. The result of this study showed that the amount of sediment yield accounts for high percentage. The average annual sedimentation is 41.60 tones per hectometer in the period of 2005 to 2010, soil erosion were classified by 5 levels. In which, the less deleterious erosion level still occupies high percentage with more than 55 % of watershed area. The main area of less deleterious soil erosion was located at high topography and high slope. The area of deleterious soil erosion occupies percentage lower than 22.63% of the entire basin, but it is also a warning sign to the extent of land degradation taking place in the basin if the erosion rate increases in the future.
Ngày nay, một trong những vấn đề cấp bách trong quản lý tài nguyên lưu vực sông là sự thoái hóa đất và đặc biệt là nguy cơ xói mòn đất xảy ra do yếu tố khí hậu phức tạp, phương thức canh tác của con người và tác động của những hoạt động phát triển kinh tế - xã hội đang diễn ra ở lưu vực. Lưu vực sông Tả Trạch là một lưu vực miền núi nằm về phía Tây - Nam của tỉnh Thừa Thiên Huế, có địa hình khá phức tạp. Mục tiêu của nghiên cứu này là ứng dụng công cụ SWAT để mô phỏng xói mòn đất ở lưu vực sông Tả Trạch thuộc tỉnh Thừa Thiên Huế từ năm 2005 đến năm 2010. Kết quả của nghiên cứu cho thấy lượng đất bồi lắng ở lưu vực chiếm tỷ lệ cao, trung bình mỗi năm bồi lắng 41.60 tấn/ha trong giai đoạn 2005 đến 2010, mức độ xói mòn được phân cấp thành 5 cấp xói mòn. Trong đó, mức độ xói mòn ít nguy hại chiếm ở tỷ lệ cao hơn 55 % diện tích lưu vực, chủ yếu phân bố ở những khu vực có địa hình cao, độ dốc lớn. Diện tích xói mòn nguy hại chiếm tỷ lệ thấp hơn 22,63% diện tích toàn lưu vực nhưng đây cũng là một dấu hiệu báo động cho mức độ thoái hóa đất diễn ra ở lưu vực trong tương lai nếu mức xói mòn này tăng lên.

Coastal areas of Southeast Asia are progressively threatened by flooding as a consequence of more frequent precipitation extremes and rising sea levels. Especially urban areas are affected by flood risk which is additionally increased by surface subsidence related to building activities and groundwater extraction. However, the severity of subsidence as well as its triggers and environmental interrelations are only little understood. This study measures surface subsidence for Hue city by using persistent scatterer radar interferometry (PS-InSAR). A series of 53 images acquired by the Sentinel-1 radar satellite between 2018 and 2019 was analyzed to reliably retrieve surface changes at the millimeter scale. The overall displacement ranges between -25 and +10 millimeters per year. Its spatial distribution was then compared to the extent of different soil types in the study area to conduct an analysis of variance (ANOVA). The results confirmed a significant difference between the soil types with Plinthic Acrisols as the soil type having the largest negative average surface velocity. Possible triggers are the intrusion of slack water from the surrounding rice cultivation areas and construction activities which lead to increasing weight and soil compaction. The findings shall raise awareness for the topic and underline the demand for further research.
Mưa lớn và nước biển dâng là những nguyên nhân gây lũ lụt ngày càng nghiêm trọng ở các khu vực ven biển Đông Nam Á. Đặc biệt việc gia tăng công trình xây dựng và khai thác nước ngầm gây sụt lún bề mặt dẫn đến ngập lụt ở các vùng đô thị. Tuy nhiên, các nghiên cứu về mối tương quan giữa sụt lún bề mặt với các hiện tượng môi trường chưa được chú trọng nhiều. Trong nghiên cứu này, độ lún bề mặt của thành phố Hue được đo bằng phương pháp giao thoa radar tán xạ liên tục (PS-InSAR). Phân tích 53 ảnh vệ tinh Sentinel-1 từ năm 2018-2019 cho thấy sự thay đổi tổng thể bề mặt dao động từ -25mm đến 10mm mỗi năm. Phân tích phương sai (ANOVA) cho thấy sự thay đổi bề mặt khác nhau tùy từng loại đất, trong đó đất đỏ vàng (Plinthic Acrisols) có tốc độ sụt lún trung bình cao nhất. Các tác nhân có thể là do sự xâm nhập của nước từ các vùng trồng lúa xung quanh và các hoạt động xây dựng dẫn đến tăng trọng lượng và nén đất. Những phát hiện này là cơ hội nâng cao nhận thức về sự sụt lún bề mặt và cần được nghiên cứu thêm.

Le changement climatique dû à l'augmentation des émissions de gaz à effet de serre est considéré comme l'un des principaux défis pour les êtres humains dans 21ème siècle. Il conduira à des changements dans les précipitations, l'humidité atmosphérique, augmentation de l'évaporation et probablement augmenter la fréquence des événements extrêmes. Les conséquences de ces phénomènes auront une influence sur de nombreux aspects de la société humaine. Donc, il y a une nécessité d'avoir une estimation robuste et précise de la variation des facteurs naturels dus au changement climatique, au moins dans les événements de cycle et d'inondation hydrologiques pour fournir une base solide pour atténuer les impacts du changement climatique et s'adapter à ces défis. Le but de cette étude est de présenter une méthodologie pour évaluer les impacts de différents scénarios de changement climatique sur une zone inondable du bassin de la rivière côtière dans la région centrale du Viet Nam - bassin versant de Vu Gia Thu Bon. Les simulations hydrologiques sont basées sur un modèle hydrologique déterministe validé qui intègre la géologie, les sols, la topographie, les systèmes fluviaux et les variables climatiques. Le climat de la journée présente, sur la période de 1991-2010 a été raisonnablement simulée par le modèle hydrologique. Climat futur (2091-2100) information a été obtenue à partir d'une réduction d'échelle dynamique des modèles climatiques mondiaux. L'étude analyse également les changements dans la dynamique des inondations de la région de l'étude, le changement hydrologique et les incertitudes du changement climatique simulation
Climate change due to the increase of greenhouse gas emissions is considered to be one of the major challenges to mankind in the 21st century. It will lead to changes in precipitation, atmospheric moisture, increase in evaporation and probably a higher frequency of extreme events. The consequences of these phenomena will have an influence on many aspects of human society. Particularly at river deltas, coastal regions and developing countries, the impacts of climate change to socio-economic development become more serious. So there is a need for a robust and accurate estimation of the variation of natural factors due to climate change, at least in the hydrological cycle and flooding events to provide a strong basis for mitigating the impacts of climate change and to adapt to these challenges. The aim of this study is to present a methodology to assess the impacts of different climate change scenarios on a flood prone area of a coastal river basin in the central region of Viet Nam – Vu Gia Thu Bon catchment. The hydrological simulations are based on a validated deterministic hydrological model which integrates geology, soil, topography, river systems and climate variables. The present day climate, over the period of 1991-2010 was reasonably simulated by the hydrological model. Future climate (2091-2100) information was obtained from a dynamical downscaling of the global climate models. The study also analyzes the changes in the flood dynamics of the study region, the hydrological shift and the uncertainties of climate change simulation

There has been rapid change in the landcover/landuse in the Mekong delta, Viet Nam. The landcover/landuse has changed very fast due to intense population pressure, agriculture/aquaculture farming and timber collection in the coastal areas of the delta. The changing landuse pattern in the coastal areas of the delta is threatened to be flooded by sea level rise; sea level is expected to rise 33 cm until 2050; 45 cm until 2070 and 1 m until 2100. The coastline along the eastern Mekong delta has never been static, but the loss of mangrove forests along the coast has intensified coastline change. The objective of the present study is to map the changes in landcover/landuse along the eastern coast of the Mekong delta; and to detect the changes in position of the eastern coastline over the time period from 1989 to 2002.To detect changes in landuse, two satellite images of the same season, acquired by the TM sensor of Landsat 5 and the ETM+ sensor of Landsat 7 were used. The TM image was acquired on January 16, 1989 and ETM+ image was acquired on February 13, 2002. The landcover/landuse classes selected for the study are water, forest, open vegetation, soil and shrimp farms. Image differencing and post classification comparison are used to detect the changes between two time periods. Image to image correction technique is used to align satellite images. Maximum likelihood supervised classification technique is used to classify images. The result of the classification consists of five classes for 1989 and 2002, respectively. Overall accuracies of 87.5% and 86.8%, with kappa values of 0.85 and 0.84 are obtained for landuse 1989 and landuse 2002, respectively. The overall accuracy for the change map is 82% with kappa value 0.80. Post classification comparison is carried out in this study based on the supervised classification results. According to the results obtained from the post classification comparison, a significant decrease of 48% in forest and a significant increase of 74% in open vegetation and 21% in shrimp farms area observed over the entire study area. The coastline obtained by the combination of histogram thresholding and band ratio showed an overall advancement towards the South China Sea. The results showed that new land patches emerged along the eastern coast. The amount of new land patches appeared along the coast of the Mekong delta is approximately 2% of the entire study area.

Research Doctorate - Doctor of Philosophy (PhD)
Vietnam has been extensively impacted by flooding historically, sustaining heavy losses in human life, and damage to housing, agriculture, water resources, and transportation. Although the Vietnamese government has focussed on physical measures of flood defence such as dykes and early warning systems, the country still lacks flood risk assessment tools and methodologies developed at national and local levels, and holistic flood risk management (FRM) frameworks. In this research, Vietnam’s national disaster database was first sourced, and the data was collected and analysed to examine the flood risk of Vietnam’s regions and provinces by using a new approach, multi-criteria decision techniques and statistical analysis. Second, the study investigated the flood fatalities in Vietnam by using statistical machine learning techniques and the national disaster database. Third, the study developed a novel flood risk assessment model that can rapidly create a flood risk map for a local scale by using spatial multi-criteria decision analysis and historical flood mark data. Fourth, FRM activities were investigated via in-depth interviews with decision makers FRM at the provincial, district, and commune levels in Quang Nam province, along with the legal and institutional frameworks. The results have been published in several high ranking peer-reviewed journals. The key findings have led to recommendations for flood risk evaluation at the national level, flood fatality analysis, spatial multi-criteria decision analysis for flood hazard and flood risk assessments, and investigation of FRM approaches from legal and institutional frameworks to practice at local levels. This research project has broad implications for future efforts to mitigate flooding in Vietnam.

Defense date: 17 June 2010
Examining Board: Prof. Morten Ravn, University College London, Supervisor Prof. Stefan Dercon, University of Oxford Prof. Massimiliano Marcellino, EUI Prof. Guglielmo Weber, University of Padova
Individuals living in developing economies are subject to a wide variety of risks. Moreover, since private and public formal institutions designed to help individuals coping with risks tend to be weaker and narrower than in rich countries, these risks very often bear a heavy burden on welfare. If the preferences of agents can be characterized by concave utility functions, these agents will want to spread risk across time and among themselves. We focus here on mechanisms allowing agents to share risk among themselves, and we look more particularly at environments where formal insurance options are incomplete or absent. This thesis offers three chapters which goal is to analyze the extent to which risk sharing is affected by imperfections in the insurance or in the credit markets. In the first two chapters, we take a microeconomic perspective and we examine how rural farmers cope with income shocks in village economies characterized by the absence of formal insurance markets. In the last chapter, we adopt a macroeconomic perspective and we look at the role of the domestic financial sector development in fostering risk sharing through financial integration between countries.

碩士
大葉大學
環境工程學系碩士班
101
Human health was considered as a global issue all over the world and gradually attracted social concern. The more development we have, the more health problems we need to address. It can be caused by many different factors such as viruses, bacteria, eating, drinking, smoking, and chemical substances which concerned recently, especially heavy metals which are not only necessary but also dangerous to human health; it can cause acute or chronic effects though a small content of them. Ingestion food accumulated heavy metals is one of main causes making heavy metals enter into human bodies, including vegetables irrigated by urban wastewater. Researching and assessing of heavy metals’ effects on human have been carried out long time ago. Nevertheless, Health Risk Assessment has carried out for the last few decades and still in gradual development. In 2000s, EPA’s risk assessment principles and practices build on our own risk assessment and make a background for other organizations develop it afterwards. It consists of four steps: Hazard Identification, Dose-Response Assessment, Exposure Assessment and Risk Characterization. This is the main methodology of the study. In addition, applying the Health Risk Assessment methodology to assess the potential health risk from heavy metals’ exposure accumulated in vegetables in Vinh Quynh – Thanh Tri – Hanoi got some results. Regarding to non-carcinogenic effects, all the values of HIs of adults and children were higher than 1, especially HIs of children. With carcinogenic effects, the UCL Risk values was pointed that there was one extra cancer death in 10,000 people exposed with Arsenic in study area. In short, people in study area are potential health risk from heavy metals, which accumulated in vegetables. Key words: Health Risk Assessment, urban wastewater, heavy metals, vegetables, accumulated

Research Doctorate - Doctor of Philosophy (PhD)
Introduction: Surveillance data and other studies have indicated that the prevalence of overweight and obesity in preschool children in Ho Chi Minh City (HCMC) is increasing, particularly in urban areas. No studies have examined the speed at which this public health problem is emerging in child populations in urban Vietnam. Knowledge of the risk factors for preschool-aged child obesity is limited since earlier studies have been cross-sectional in design and potential risk factors at different levels have not been fully investigated. Objectives: This study aimed to assess the prevalence and trends in overweight and obesity, and to identify the risk factors associated with longitudinal changes in adiposity over a one year period in preschool children in urban areas of HCMC. In addition, a sub-study aimed to validate a proxy-questionnaire for use in measuring physical activity of preschool children. Method: Based on the available data from a cross-sectional study conducted with preschool children in HCMC in 2002, a restricted sample of 492 children aged four to five years from urban areas of HCMC was used for examining the trends in overweight and obesity in this child population, over the period from 2002 to 2005. The original study using the multi-stage cluster sampling was performed in preschool children aged one to six years in both urban and sub-urban areas of HCMC. A total of 1780 children aged one to six years participated in this study. Anthropometry of the subjects was measured using standard methods. Socio-demographic information was collected using a self-administered questionnaire. The one year follow-up study, using multi-stage cluster sampling, was conducted from 2005 to 2006 with children aged four to five years in preschools in urban areas of HCMC. At baseline, 670 children participated in the study and of these, 526 children completed two follow-up measurements at 6 month intervals. Information on neighbourhood, preschool and home environments, socio-economic status, the child’s and parental characteristics were collected using pre-coded, structured, interviewer-administered questionnaires. Dietary intake and physical activity were measured in the home and preschool settings using modified, validated questionnaires. Anthropometry including weight, height, skinfold thickness at triceps, subscapular and suprailiac sites were measured using standard methods. The trends in overweight and obesity were examined based on data from the 2002 study and the baseline study of the cohort study. Data were collected in 2002 and made available for these secondary analyses. The validation study of the proxy-questionnaire to measure physical activity of children aged four to five years was conducted from July, 2005 to November, 2005, using accelerometers as the criterion method. A subset of 83 children from the entire cohort study participated in this study. Physical activity data over the three months, reported by the teacher and the parents, were compared with data collected from the accelerometers for seven consecutive days. Main outcomes: Body mass index (BMI) was calculated from measured weight and height. Overweight and obesity were defined using IOTF cut-off points. Underweight was classified using the 5th percentile cut-off point for weight for age, based on the 2000 CDC Growth Reference. Results: The findings indicated that the significance of overweight and obesity in preschool children in urban areas of HCMC is not only in its magnitude (obverweight: 20.5% and obesity: 16.3% in 2005), but also in the rapidly increasing trend in prevalence from 21.4% in 2002 to 36.8% in 2005. There exists an imbalance in food intake in this young child population. Dietary patterns have shifted towards higher energy obtained from protein and fat (particularly animal protein and fat) and less energy from carbohydrates, than is recommended. The risk factors of overweight and obesity in the four to six year old child population in HCMC were identified at multiple levels. The contextual variables in the community, school and home environments, interacted with individual characteristics influencing the changes in adiposity and overweight and obesity development over time. Risk factors for changes in adiposity and risk of developing overweight and obesity differed for boys and girls. The proxy-questionnaire was shown to be valid for ranking the child’s sedentary behaviour but it was not suitable for measuring the child’s physical activity patterns in absolute values. Conclusion: An obesity epidemic has been taking place in the young child population in urban areas of HCMC. Boys appear to be more vulnerable to this epidemic than girls. The diet of this child population has shifted to higher energy from protein and fat, and less energy from carbohydrate. The aetiology of overweight and obesity of preschool children ismulti-factorial. It is time for action to control this public health problem in young children in urban areas of HCMC, Vietnam.

Research Doctorate - Doctor of Philosophy (PhD)
Introduction: Surveillance data and other studies have indicated that the prevalence of overweight and obesity in preschool children in Ho Chi Minh City (HCMC) is increasing, particularly in urban areas. No studies have examined the speed at which this public health problem is emerging in child populations in urban Vietnam. Knowledge of the risk factors for preschool-aged child obesity is limited since earlier studies have been cross-sectional in design and potential risk factors at different levels have not been fully investigated. Objectives: This study aimed to assess the prevalence and trends in overweight and obesity, and to identify the risk factors associated with longitudinal changes in adiposity over a one year period in preschool children in urban areas of HCMC. In addition, a sub-study aimed to validate a proxy-questionnaire for use in measuring physical activity of preschool children. Method: Based on the available data from a cross-sectional study conducted with preschool children in HCMC in 2002, a restricted sample of 492 children aged four to five years from urban areas of HCMC was used for examining the trends in overweight and obesity in this child population, over the period from 2002 to 2005. The original study using the multi-stage cluster sampling was performed in preschool children aged one to six years in both urban and sub-urban areas of HCMC. A total of 1780 children aged one to six years participated in this study. Anthropometry of the subjects was measured using standard methods. Socio-demographic information was collected using a self-administered questionnaire. The one year follow-up study, using multi-stage cluster sampling, was conducted from 2005 to 2006 with children aged four to five years in preschools in urban areas of HCMC. At baseline, 670 children participated in the study and of these, 526 children completed two follow-up measurements at 6 month intervals. Information on neighbourhood, preschool and home environments, socio-economic status, the child’s and parental characteristics were collected using pre-coded, structured, interviewer-administered questionnaires. Dietary intake and physical activity were measured in the home and preschool settings using modified, validated questionnaires. Anthropometry including weight, height, skinfold thickness at triceps, subscapular and suprailiac sites were measured using standard methods. The trends in overweight and obesity were examined based on data from the 2002 study and the baseline study of the cohort study. Data were collected in 2002 and made available for these secondary analyses. The validation study of the proxy-questionnaire to measure physical activity of children aged four to five years was conducted from July, 2005 to November, 2005, using accelerometers as the criterion method. A subset of 83 children from the entire cohort study participated in this study. Physical activity data over the three months, reported by the teacher and the parents, were compared with data collected from the accelerometers for seven consecutive days. Main outcomes: Body mass index (BMI) was calculated from measured weight and height. Overweight and obesity were defined using IOTF cut-off points. Underweight was classified using the 5th percentile cut-off point for weight for age, based on the 2000 CDC Growth Reference. Results: The findings indicated that the significance of overweight and obesity in preschool children in urban areas of HCMC is not only in its magnitude (obverweight: 20.5% and obesity: 16.3% in 2005), but also in the rapidly increasing trend in prevalence from 21.4% in 2002 to 36.8% in 2005. There exists an imbalance in food intake in this young child population. Dietary patterns have shifted towards higher energy obtained from protein and fat (particularly animal protein and fat) and less energy from carbohydrates, than is recommended. The risk factors of overweight and obesity in the four to six year old child population in HCMC were identified at multiple levels. The contextual variables in the community, school and home environments, interacted with individual characteristics influencing the changes in adiposity and overweight and obesity development over time. Risk factors for changes in adiposity and risk of developing overweight and obesity differed for boys and girls. The proxy-questionnaire was shown to be valid for ranking the child’s sedentary behaviour but it was not suitable for measuring the child’s physical activity patterns in absolute values. Conclusion: An obesity epidemic has been taking place in the young child population in urban areas of HCMC. Boys appear to be more vulnerable to this epidemic than girls. The diet of this child population has shifted to higher energy from protein and fat, and less energy from carbohydrate. The aetiology of overweight and obesity of preschool children ismulti-factorial. It is time for action to control this public health problem in young children in urban areas of HCMC, Vietnam.

博士
逢甲大學
土木水利工程與建設規劃博士學位學程
107
Flooding is considered the most frequent and severe natural disaster in Vietnam. It causes serious damage to human life, properties every year, especially in the populous city. The Hoan Kiem district- Hanoi is a typical example of inundation situation by flooding. The aim of this study is to propose an integrated model which takes hazard, vulnerability, and exposure into account to establish the flood risk assessment. Flood hazard map was detected based on the difference about water body between in interpreting from the Sentinel-1 image taken at the flooding time on 18 July 2017 and permanent water from multi-period Landsat images taken in dry and rainy seasons. The flood vulnerability map was assigned based on the combination of five indices: slope, land use, green density, sewer density and distance from drainage. They were then weighted overlay based on the AHP method. The flood exposure map created as the composition of economic land value and built-up density. In which, the economic land value was designed by assigning prices to each category: residential, commercial, non-agricultural and agricultural land. Built-up density was determined based on the Normalized Difference Built-up Index (NDBI). To assess the result accuracy, flooding- based field verification and historical flood map was used to compare with the result in this study. The Correlation Coefficient and the Coefficient of Determination were used to indicate and explain the relationship between the flood risk map in this study with previous floods. Basically, the result was considered good for flood area estimation. As the result, the flood risk map was classified into five levels: very low, low, moderate, high and very high. The result indicates the most susceptibility areas with flood and can be used to identify the planning recommendations. Besides the flooding causes due to heavy rainfall with high intensity, exceeding permeability and drainage possibility, the change of land use/land cover and high drainage density are the dominant cause of flooding in the study area.

碩士
開南大學
觀光運輸學院碩士班
107
Vietnam is no longer just a factory in Southeast Asia but has also become a market in Southeast Asia. This has attracted large companies to invest in Vietnam. These foreign investors must pay attention to the risks that may arise in their investments. This study will provide and analyze the risks that investors often encounter when investing in Vietnam. This study applies the fuzzy linguistic preference relations (Fuzzy LinPreRa), based on Fuzzy Set Theory, proposed by Wang and Chen (2008) to interview experts and practitioners for the assessment of overseas investment risk factors. The Vietnamese electric motorcycle industry was chosen as an example to judge the degree of impact of the unfavorable state on the investment. The result of the risk assessment will generate the relative severity of each factor that will be used to identify the probable problem of the industry. Moreover, the most serious risks that will be identified after this study can be used as a reference for foreign investors for as factors in their possible investment options. This study also aims to establish a systematic assessment of risk factors in overseas investments. Decision makers analyze the perceptions of different types of evaluators in overseas investments and applies group decisions to improve the correctness of decisions.