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Sample records for mekong delta vietnam

  1. The spatial distribution of vulnerability to the health impacts of flooding in the Mekong Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Phung, Dung; Rutherford, Shannon; Dwirahmadi, Febi; Chu, Cordia; Do, Cuong Manh; Nguyen, Thuy; Duong, Nam Chi

    2016-06-01

    Flooding causes significant public health issues. The Mekong Delta has been considered the region to be the most vulnerable to flooding in Vietnam. This study assessed the spatial vulnerability of the health impacts of flooding in the Mekong Delta region, Vietnam. This study applied a vulnerability assessment framework which was computed as the function of three dimensions: exposure, sensitivity, and adaptive capacity. The indicators for each dimension were derived from the relevant literature, consultations with experts, and data availability. An analytic hierarchy process (AHP) and a principal component analysis (PCA) were used to determine the weight of indicators. Vulnerability indexes (VIs) were then computed for each province. A total of 29 indicators (sensitivity index, 14; adaptive capacity index, 13; and exposure index, 2) were employed to evaluate the vulnerability to the health impacts of flooding at a provincial level. The results of AHP revealed that the highest VIs were found in the Dong Thap and An Giang provinces (VI, 1.948 and 1.574, respectively). VIs were distributed with higher indexes in upstream provinces close to a river than in coastal provinces. PCA generated three components from the 29 indicators, and the VIs computed from the PCA method are in substantial agreement with the AHP method (ICC = 0.71, p < 0.05). The vulnerability to the health impacts of flooding varies from province to province in the Mekong Delta region in Vietnam. Individual plans for health preparedness and adaption to flooding should be developed for each province in the Mekong Delta region.

  2. Assessing the prehistoric shoreline changes of the Mekong delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Tamura, T.; Saito, Y.; Nguyen, V. L.; Ta, T. K. O.; Bateman, M. D.; Sato, A.

    2014-12-01

    The environment and sustainability of deltaic lowlands have been threatened by combined impacts of climate changes, human activities and land subsidence. The Mekong delta has also been disturbed by the construction of upstream river dams and fluvial dredging, and we have a limited knowledge of its morphodynamics response to fluctuations in Asian monsoons that governs the coastal sediment dynamics. In order to understand the recent shoreline changes of the Mekong delta, we attempted to reconstruct the prehistoric changes based on landform records and their chronology. Thirteen optically-stimulated luminescence (OSL) ages of chenier, a record of past shoreline, were obtained from the Soc Trang coastal plain, southwestern part of the delta. The OSL ages are younger than 2770 yr BP, and become younger seawards concordantly with the coastal progradation that cheniers document. The progradation rate has changed drastically; it was 8 m/yr, 31 m/yr, and 5 m/yr during periods of 2770-1370 yr BP, 1370-590 yr BP, and 590 yr BP to present, respectively. The rapid progradation during 1370-590 yr BP did not form cheniers, resulting in an extensive inter-ridge swale. Cheniers generally form in relations to erosion of muddy coast. The chenier distribution and drastic changes in progradation rate were resulted from fluctuations in relative importance of longshore sediment removal to seaward sediment accretion. Beach ridges in the Tra Vinh coastal plain, northeast of the Soc Trang, also indicate similar and synchronous fluctuations in the longshore sediment transport. The dominance of the longshore sediment transport after 590 yr BP is thought caused by the strengthened winter monsoon that drives the southwestward longshore current, which is possibly related to the beginning of the Little Ice Age. Many cheniers occur along the present shoreline in relation to the low progradation rate, and possibly some sporadic erosion after 590 yr BP. Some evidences have suggested that the winter

  3. The spatial distribution of vulnerability to the health impacts of flooding in the Mekong Delta, Vietnam.

    PubMed

    Phung, Dung; Rutherford, Shannon; Dwirahmadi, Febi; Chu, Cordia; Do, Cuong Manh; Nguyen, Thuy; Duong, Nam Chi

    2016-06-01

    Flooding causes significant public health issues. The Mekong Delta has been considered the region to be the most vulnerable to flooding in Vietnam. This study assessed the spatial vulnerability of the health impacts of flooding in the Mekong Delta region, Vietnam. This study applied a vulnerability assessment framework which was computed as the function of three dimensions: exposure, sensitivity, and adaptive capacity. The indicators for each dimension were derived from the relevant literature, consultations with experts, and data availability. An analytic hierarchy process (AHP) and a principal component analysis (PCA) were used to determine the weight of indicators. Vulnerability indexes (VIs) were then computed for each province. A total of 29 indicators (sensitivity index, 14; adaptive capacity index, 13; and exposure index, 2) were employed to evaluate the vulnerability to the health impacts of flooding at a provincial level. The results of AHP revealed that the highest VIs were found in the Dong Thap and An Giang provinces (VI, 1.948 and 1.574, respectively). VIs were distributed with higher indexes in upstream provinces close to a river than in coastal provinces. PCA generated three components from the 29 indicators, and the VIs computed from the PCA method are in substantial agreement with the AHP method (ICC = 0.71, p < 0.05). The vulnerability to the health impacts of flooding varies from province to province in the Mekong Delta region in Vietnam. Individual plans for health preparedness and adaption to flooding should be developed for each province in the Mekong Delta region.

  4. Development of sea level rise scenarios for climate change assessments of the Mekong Delta, Vietnam

    USGS Publications Warehouse

    Doyle, Thomas W.; Day, Richard H.; Michot, Thomas C.

    2010-01-01

    Rising sea level poses critical ecological and economical consequences for the low-lying megadeltas of the world where dependent populations and agriculture are at risk. The Mekong Delta of Vietnam is one of many deltas that are especially vulnerable because much of the land surface is below mean sea level and because there is a lack of coastal barrier protection. Food security related to rice and shrimp farming in the Mekong Delta is currently under threat from saltwater intrusion, relative sea level rise, and storm surge potential. Understanding the degree of potential change in sea level under climate change is needed to undertake regional assessments of potential impacts and to formulate adaptation strategies. This report provides constructed time series of potential sea level rise scenarios for the Mekong Delta region by incorporating (1) aspects of observed intra- and inter-annual sea level variability from tide records and (2) projected estimates for different rates of regional subsidence and accelerated eustacy through the year 2100 corresponding with the Intergovernmental Panel on Climate Change (IPCC) climate models and emission scenarios.

  5. Contamination of Salmonella in retail meats and shrimps in the Mekong Delta, Vietnam.

    PubMed

    Phan, Tran Thi; Khai, Ly Thi Lien; Ogasawara, Natsue; Tam, Nguyen Thu; Okatani, Alexandre Tomomitsu; Akiba, Masato; Hayashidani, Hideki

    2005-05-01

    From March 2000 to September 2001, 608 samples of retail meat (136 pork, 70 beef, 202 chicken, and 200 ducks) and 110 samples of retail shrimp from six provinces of the Mekong Delta in Vietnam were collected individually and examined for the prevalence of Salmonella. Of the 718 samples examined, 243 (33.8%) were Salmonella positive. Salmonella was isolated from 69.9% of the pork samples, 48.6% of the beef samples, 21.0% of the chicken meat samples, 22.3% of the duck meat samples, and 24.5% of the shrimp samples. From 261 Salmonella isolates, 24 different serovars were identified. The predominant serovars of the isolates were Salmonella Derby, Salmonella Weltevreden, and Salmonella London in pork; Salmonella Weltevreden, Salmonella London, and Salmonella Dessau in beef; Salmonella Emek, Salmonella Typhimurium, and Salmonella Dessau in chicken meat; Salmonella Lexington, Salmonella Derby, and Salmonella Dessau in duck meat; and Salmonella Weltevreden, Salmonella Tennessee, and Salmonella Dessau in shrimps. Salmonella Bovismorbificans, Salmonella Derby, Salmonella Dessau, and Salmonella Weltevreden were the most common serovars in all the samples examined. These results indicate a high rate of contamination by Salmonella in retail meats and shrimps in the Mekong Delta, Vietnam.

  6. Climate Change Impact On Mekong Delta of Vietnam in recent years

    NASA Astrophysics Data System (ADS)

    Le, L. T. X., III

    2015-12-01

    In recent years, the climate change signal increase globally. Abnormal changes of weather tends increasingly detrimental to human life, such as natural disasters occur with increasing level of more severe. Climate change is one the biggest challenges, and is a potential threat to humans. The impact of climate change increases the number and extent of the disaster fierce exists as typhoons, floods, droughts ... Global warming and sea level rise increases the area of flooding, saline intrusion and erosion in the delta region may cause farmers to lose the opportunity to produce, source of life their only. Impact of climate change on people in the community, but poor farmers in the developing countries like our country, women are the most severe consequences In this section, we summarize changes in climate on the territory of Vietnam, especially in Mekong Delta evaluate causes and its relationship to changes in global climate and region. Along with the analysis of characteristics of climate changes over time and through space to help the evolution of the standard deviation (average deviation from the standard of the period from 1971 to 2015) may indicate that the characteristic gas scenes took place related to global climate change ... Vietnam's territory stretches over approximately 15 latitude, the terrain is very complex, located in the interior full of tropical Southeast Asia. Vietnam climate strongly influenced by the Asian monsoon, monsoon and Northern Hemisphere especially the ENSO activity in the equatorial region and the Pacific Ocean. Climate Vietnam abundant and diversified, with strong ties to the region and globally.

  7. Clonal Occurrence of Salmonella Weltevreden in Cultured Shrimp in the Mekong Delta, Vietnam.

    PubMed

    Noor Uddin, Gazi Md; Larsen, Marianne Halberg; Barco, Lisa; Minh Phu, Tran; Dalsgaard, Anders

    2015-01-01

    This study investigated the occurrence, serovar and antimicrobial resistance of Salmonella spp. in shrimp samples from intensive and extensive farms located in three different provinces in the Mekong Delta, Vietnam. Shrimp from 11 of the 48 farms all contained S. Weltevreden, except for one farm yielding S. Agona, with no difference in Salmonella occurrence between the two production systems. Pulsed field gel electrophoresis (PFGE) of S. Weltevreden showed closely related XbaI pulse types, suggesting a clonal relationship despite the farms and shrimp samples being epidemiologically unrelated. S. Weltevreden was susceptible to most antimicrobials tested, with a few strains being resistant to florfenicol, chloramphenicol, sulfamethoxazole or trimethoprim. Future studies of the ecology of S. Weltevreden should establish if this serovar may survive better and even multiply in warm-water shrimp farm environments compared to other Salmonella serovars.

  8. Clonal Occurrence of Salmonella Weltevreden in Cultured Shrimp in the Mekong Delta, Vietnam

    PubMed Central

    Noor Uddin, Gazi Md.; Larsen, Marianne Halberg; Barco, Lisa; Minh Phu, Tran; Dalsgaard, Anders

    2015-01-01

    This study investigated the occurrence, serovar and antimicrobial resistance of Salmonella spp. in shrimp samples from intensive and extensive farms located in three different provinces in the Mekong Delta, Vietnam. Shrimp from 11 of the 48 farms all contained S. Weltevreden, except for one farm yielding S. Agona, with no difference in Salmonella occurrence between the two production systems. Pulsed field gel electrophoresis (PFGE) of S. Weltevreden showed closely related XbaI pulse types, suggesting a clonal relationship despite the farms and shrimp samples being epidemiologically unrelated. S. Weltevreden was susceptible to most antimicrobials tested, with a few strains being resistant to florfenicol, chloramphenicol, sulfamethoxazole or trimethoprim. Future studies of the ecology of S. Weltevreden should establish if this serovar may survive better and even multiply in warm-water shrimp farm environments compared to other Salmonella serovars. PMID:26222547

  9. Hydrogeologic reconnaissance of the Mekong Delta in South Vietnam and Cambodia

    USGS Publications Warehouse

    Anderson, Henry R.

    1978-01-01

    The present report describes the results of a hydrogeologic reconnaissance in the Mekong Delta region by the writer, a hydrogeologist of the U.S. Geological Survey, while on assignment as an adviser to the Vietnamese Directorate of Water Supply from October 1968 to April 1970 under the auspices of the U.s. Agency for International Development. The delta of the Mekong River, comprising an area of about 70,000 square kilometres in South Vietnam and Cambodia, is an almost featureless plain rising gradually from sea level to about 5 metres above sea level at its apex 300 kilometres inland. Most of the shallow ground water in the Holocene Alluvium of the delta in Vietnam is brackish or saline down to depths of 50 to 100 metres. Moreover, in the Dong Thap Mu?oi (Plain of Reeds) the shallow ground water is alum-bearing. Locally, however, perched bodies of fresh ground water occur in ancient beach and dune ridges and are tapped by shallow dug wells or pits for village and domestic water supply. The Old Alluvium beneath the lower delta contains freshwater in some areas, notably in the Ca Mau Peninsula and adjacent areas, in the viciniy of Bau Xau near Saigon, and in the Tinh Long An area. Elsewhere in the lower delta both the Holocene and Old Alluvium may contain brackish or saline water from the land surface to depths of as much as 568 metres, as for example in Tinh Vinh Binh. Ground water in the outcrop area of Old Alluvium northwest of Saigon is generally fresh and potable, but high iron and low pH are locally troublesome. Although considerable exploratory drilling for ground water down to depths of as much as 568 metres has already been completed, large areas of the delta remain yet to be explored before full development of the ground-water potential can be realized. With careful development and controlled management to avoid saltwater contamination, however, it is estimated that freshwater aquifers could provide approximately 80 percent of existing needs for village

  10. Gender relations and sexual communication among female students in the Mekong River Delta of Vietnam.

    PubMed

    Bui, Thanh Cong; Diamond, Pamela M; Markham, Christine; Ross, Michael W; Nguyen-Le, Thanh-An; Tran, Ly Hai Thi

    2010-08-01

    Young women's ability to pursue a safer-sex life in line with their wishes is crucial to their sexual health. Although some previous observations have suggested that young women's lack of ability to negotiate safer sex is due to gender power imbalances in the culture of Vietnam, studies that have tested this hypothesis explicitly and quantitatively are few and far between. The present study aimed to test the association between perceived gender relations and perceived self-efficacy in communicating sexual matters among undergraduate female students in the Mekong River Delta of Vietnam. The analysis involved secondary data from 260 subjects from a larger survey regarding gender equity. Structural equation modeling was used to examine the study's hypothesis. Results showed that adherence to traditional gender roles and norms was significantly associated with female students' reduced self-efficacy to communicate on safer-sex matters, such as refusing unwanted sex or requesting condom use. This association remained invariant in the cross-validation process between partnered and unpartnered groups. Programmes that aim to promote safer-sex negotiation and practices for this population may need to address the influence of gender relations and power.

  11. Occurrence and Dissipation of the Antibiotics Sulfamethoxazole, Sulfadiazine, Trimethoprim, and Enrofloxacin in the Mekong Delta, Vietnam.

    PubMed

    Nguyen Dang Giang, Chau; Sebesvari, Zita; Renaud, Fabrice; Rosendahl, Ingrid; Hoang Minh, Quang; Amelung, Wulf

    2015-01-01

    The Mekong Delta in Vietnam has seen a rapid development and intensification of aquaculture in the last decades, with a corresponding widespread use of antibiotics. This study provides information on current antibiotic use in freshwater aquaculture, as well as on resulting antibiotic concentrations in the aquatic environment of the Mekong Delta. Two major production steps, fish hatcheries and mature fish cultivation, were surveyed (50 fish farm interviews) for antibiotic use. Different water sources, including surface water, groundwater and piped water (164 water samples) were systematically screened for antibiotic residues. To better understand antibiotic fate under tropical conditions, the dissipation behavior of selected antibiotics in the aquatic environment was investigated for the first time in mesocosm experiments. None of the investigated antibiotics were detected in groundwater and piped water samples. Surface water, which is still often used for drinking and domestic purposes by local populations, contained median concentrations of 21 ng L-1 sulfamethoxazole (SMX), 4 ng L-1 sulfadiazine (SDZ), 17 ng L-1 trimethoprim (TRIM), and 12 ng L-1 enrofloxacin (ENRO). These concentrations were lower than the predicted no effect concentrations (PNECs) and minimum inhibitory concentrations (MICs), suggesting limited antibiotic-related risk to aquatic ecosystems in the monitored systems. The dissipation half-lives of the studied antibiotics ranged from <1 to 44 days, depending on the availability of sunlight and sediment. Among the studied antibiotics TRIM was the most persistent in water systems. TRIM was not susceptible to photodegradation, while the dissipation of ENRO and SDZ was influenced by photolysis. The recorded dissipation models gave good predictions of the occurrence and concentrations of TRIM, ENRO and SDZ in surface water. In summary, the currently measured concentrations of the investigated antibiotics are unlikely to cause immediate risks to the

  12. Occurrence and Dissipation of the Antibiotics Sulfamethoxazole, Sulfadiazine, Trimethoprim, and Enrofloxacin in the Mekong Delta, Vietnam

    PubMed Central

    Nguyen Dang Giang, Chau; Sebesvari, Zita; Renaud, Fabrice; Rosendahl, Ingrid; Hoang Minh, Quang; Amelung, Wulf

    2015-01-01

    The Mekong Delta in Vietnam has seen a rapid development and intensification of aquaculture in the last decades, with a corresponding widespread use of antibiotics. This study provides information on current antibiotic use in freshwater aquaculture, as well as on resulting antibiotic concentrations in the aquatic environment of the Mekong Delta. Two major production steps, fish hatcheries and mature fish cultivation, were surveyed (50 fish farm interviews) for antibiotic use. Different water sources, including surface water, groundwater and piped water (164 water samples) were systematically screened for antibiotic residues. To better understand antibiotic fate under tropical conditions, the dissipation behavior of selected antibiotics in the aquatic environment was investigated for the first time in mesocosm experiments. None of the investigated antibiotics were detected in groundwater and piped water samples. Surface water, which is still often used for drinking and domestic purposes by local populations, contained median concentrations of 21 ng L-1 sulfamethoxazole (SMX), 4 ng L-1 sulfadiazine (SDZ), 17 ng L-1 trimethoprim (TRIM), and 12 ng L-1 enrofloxacin (ENRO). These concentrations were lower than the predicted no effect concentrations (PNECs) and minimum inhibitory concentrations (MICs), suggesting limited antibiotic-related risk to aquatic ecosystems in the monitored systems. The dissipation half-lives of the studied antibiotics ranged from <1 to 44 days, depending on the availability of sunlight and sediment. Among the studied antibiotics TRIM was the most persistent in water systems. TRIM was not susceptible to photodegradation, while the dissipation of ENRO and SDZ was influenced by photolysis. The recorded dissipation models gave good predictions of the occurrence and concentrations of TRIM, ENRO and SDZ in surface water. In summary, the currently measured concentrations of the investigated antibiotics are unlikely to cause immediate risks to the

  13. How important are rats as vectors of leptospirosis in the Mekong Delta of Vietnam?

    PubMed

    Loan, Hoang Kim; Van Cuong, Nguyen; Takhampunya, Ratree; Kiet, Bach Tuan; Campbell, James; Them, Lac Ngoc; Bryant, Juliet E; Tippayachai, Bousaraporn; Van Hoang, Nguyen; Morand, Serge; Hien, Vo Be; Carrique-Mas, Juan J

    2015-01-01

    Leptospirosis is a zoonosis known to be endemic in the Mekong Delta of Vietnam, even though clinical reports are uncommon. We investigated leptospira infection in rats purchased in food markets during the rainy season (October) (n=150), as well as those trapped during the dry season (February-March) (n=125) in the region using RT-PCR for the lipL32 gene, confirmed by 16S rRNA, as well as by the microscopic agglutination test (MAT). Results were compared with the serovar distribution of human cases referred from Ho Chi Minh City hospitals (2004-2012) confirmed by MAT (n=45). The MAT seroprevalence among rats was 18.3%. The highest MAT seroprevalence corresponded, in decreasing order, to: Rattus norvegicus (33.0%), Bandicota indica (26.5%), Rattus tanezumi (24.6%), Rattus exulans (14.3%), and Rattus argentiventer (7.1%). The most prevalent serovars were, in descending order: Javanica (4.6% rats), Lousiana (4.2%), Copenageni (4.2%), Cynopterie (3.7%), Pomona (2.9%), and Icterohaemorrhagiae (2.5%). A total of 16 rats (5.8%) tested positive by RT-PCR. Overall, larger rats tended to have a higher prevalence of detection. There was considerable agreement between MAT and PCR (kappa=0.28 [0.07-0.49]), although significantly more rats were positive by MAT (McNemar 29.9 (p<0.001). MAT prevalence was higher among rats during the rainy season compared with rats in the dry season. There are no current available data on leptospira serovars in humans in the Mekong Delta, although existing studies suggest limited overlapping between human and rat serovars. Further studies should take into account a wider range of potential reservoirs (i.e., dogs, pigs) as well as perform geographically linked co-sampling of humans and animals to establish the main sources of leptospirosis in the region.

  14. Bottom sediments affect Sonneratia mangrove forests in the prograding Mekong delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Nardin, William; Woodcock, Curtis E.; Fagherazzi, Sergio

    2016-08-01

    Mangrove forests exert a strong influence on tropical deltas by trapping sediments discharged by rivers and by stabilizing the substrate with roots. Understanding the dynamics of sediments and morphology in and around mangrove forests is critical in order to assess the resilience of coastlines in a period of accelerated sea level rise. In this research, sediment samples, mangrove forest characteristics, and remote sensing data are used to investigate the relationship between mangroves and sediment substrate in the Mekong Delta, Vietnam. Our data show a significant correlation between percent of sand in bottom sediments and density of Sonneratia caseolaris forest. We ascribe this result to higher sediment disturbance in muddy areas that prevents seedling establishment. This correlation potentially allows the determination of substrate characteristics from vegetation attributes detected by remote sensing, despite the impenetrability of the forest canopy. The results presented herein suggest that a supply of sand from the river and hydrodynamic processes moving the sand ashore control the density of the Sonneratia mangrove forests at this location, promoting tidal flat colonization and canopy expansion.

  15. Identification of the prediction model for dengue incidence in Can Tho city, a Mekong Delta area in Vietnam.

    PubMed

    Phung, Dung; Huang, Cunrui; Rutherford, Shannon; Chu, Cordia; Wang, Xiaoming; Nguyen, Minh; Nguyen, Nga Huy; Manh, Cuong Do

    2015-01-01

    The Mekong Delta is highly vulnerable to climate change and a dengue endemic area in Vietnam. This study aims to examine the association between climate factors and dengue incidence and to identify the best climate prediction model for dengue incidence in Can Tho city, the Mekong Delta area in Vietnam. We used three different regression models comprising: standard multiple regression model (SMR), seasonal autoregressive integrated moving average model (SARIMA), and Poisson distributed lag model (PDLM) to examine the association between climate factors and dengue incidence over the period 2003-2010. We validated the models by forecasting dengue cases for the period of January-December, 2011 using the mean absolute percentage error (MAPE). Receiver operating characteristics curves were used to analyze the sensitivity of the forecast of a dengue outbreak. The results indicate that temperature and relative humidity are significantly associated with changes in dengue incidence consistently across the model methods used, but not cumulative rainfall. The Poisson distributed lag model (PDLM) performs the best prediction of dengue incidence for a 6, 9, and 12-month period and diagnosis of an outbreak however the SARIMA model performs a better prediction of dengue incidence for a 3-month period. The simple or standard multiple regression performed highly imprecise prediction of dengue incidence. We recommend a follow-up study to validate the model on a larger scale in the Mekong Delta region and to analyze the possibility of incorporating a climate-based dengue early warning method into the national dengue surveillance system.

  16. Pesticide pollution of multiple drinking water sources in the Mekong Delta, Vietnam: evidence from two provinces.

    PubMed

    Chau, N D G; Sebesvari, Z; Amelung, W; Renaud, F G

    2015-06-01

    Pollution of drinking water sources with agrochemicals is often a major threat to human and ecosystem health in some river deltas, where agricultural production must meet the requirements of national food security or export aspirations. This study was performed to survey the use of different drinking water sources and their pollution with pesticides in order to inform on potential exposure sources to pesticides in rural areas of the Mekong River delta, Vietnam. The field work comprised both household surveys and monitoring of 15 frequently used pesticide active ingredients in different water sources used for drinking (surface water, groundwater, water at public pumping stations, surface water chemically treated at household level, harvested rainwater, and bottled water). Our research also considered the surrounding land use systems as well as the cropping seasons. Improper pesticide storage and waste disposal as well as inadequate personal protection during pesticide handling and application were widespread amongst the interviewed households, with little overall risk awareness for human and environmental health. The results show that despite the local differences in the amount and frequency of pesticides applied, pesticide pollution was ubiquitous. Isoprothiolane (max. concentration 8.49 μg L(-1)), fenobucarb (max. 2.32 μg L(-1)), and fipronil (max. 0.41 μg L(-1)) were detected in almost all analyzed water samples (98 % of all surface samples contained isoprothiolane, for instance). Other pesticides quantified comprised butachlor, pretilachlor, propiconazole, hexaconazole, difenoconazole, cypermethrin, fenoxapro-p-ethyl, tebuconazole, trifloxystrobin, azoxystrobin, quinalphos, and thiamethoxam. Among the studied water sources, concentrations were highest in canal waters. Pesticide concentrations varied with cropping season but did not diminish through the year. Even in harvested rainwater or purchased bottled water, up to 12 different pesticides were detected at

  17. Application of the Water Needs Index: Can Tho City, Mekong Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Moglia, Magnus; Neumann, Luis E.; Alexander, Kim S.; Nguyen, Minh N.; Sharma, Ashok K.; Cook, Stephen; Trung, Nguyen H.; Tuan, Dinh D. A.

    2012-10-01

    SummaryProvision of urban water supplies to rapidly growing cities of South East Asia is difficult because of increasing demand for limited water supplies, periodic droughts, and depletion and contamination of surface and groundwater. In such adverse environments, effective policy and planning processes are required to secure adequate water supplies. Developing a Water Needs Index reveals key elements of the complex urban water supply by means of a participatory approach for rapid and interdisciplinary assessment. The index uses deliberative interactions with stakeholders to create opportunities for mutual understanding, confirmation of constructs and capacity building of all involved. In Can Tho City, located at the heart of the Mekong delta in Vietnam, a Water Needs Index has been developed with local stakeholders. The functional attributes of the Water Needs Index at this urban scale have been critically appraised. Systemic water issues, supply problems, health issues and inadequate, poorly functioning infrastructure requiring attention from local authorities have been identified. Entrenched social and economic inequities in access to water and sanitation, as well as polluting environmental management practices has caused widespread problems for urban populations. The framework provides a common language based on systems thinking, increased cross-sectoral communication, as well as increased recognition of problem issues; this ought to lead to improved urban water management. Importantly, the case study shows that the approach can help to overcome biases of local planners based on their limited experience (information black spots), to allow them to address problems experienced in all areas of the city.

  18. Copper use and accumulation in catfish culture in the Mekong Delta, Vietnam.

    PubMed

    Marcussen, Helle; Løjmand, Helle; Dalsgaard, Anders; Hai, Dao M; Holm, Peter E

    2014-01-01

    Aquaculture of Pangasius hypophthalmus (striped catfish) in Vietnam reached 1.1 million tonnes in 2011 and catfish fillets are exported worldwide. The intensive cultures of catfish mainly in earth ponds have made it necessary to apply CuSO4 and other chemicals to control external parasites and other pathogens. However, accumulation of Cu in aquaculture ponds may pose a hazard to growth of fish or to the aquatic environment. The aim of this study was to determine accumulation of Cu in sediment, water and fish in a catfish pond with a history of repeated treatment with CuSO4 in the Mekong Delta, Vietnam. Copper concentrations in pond sediment were in the interval 21.3-45.7 mg kg(-1) dw and did not exceed the Vietnamese values for soil to be used for agricultural production (70 mg kg(-1) dw.). During three samplings the total mean concentration of Cu in pond water (4 μg L(-1)) did not exceed the LC50-value (70 μg L(-1)) for catfish and the mean dissolved concentration of Cu (0.986 μg L(-1)) did not seem to constitute a risk for the stability of the aquatic ecosystem. No significant variation in Cu concentrations between sampling sites in the pond and depth of sediment profile were determined. The accumulation of Cu in catfish was highest in the liver compared to the skin, gills and muscle tissue. With the current practice of removing pond sludge three to four times during a production cycle little if any Cu seems to accumulate in catfish ponds despite repeated anti-parasite treatments with CuSO4. Further studies are needed to assess the eco-toxicity and impact on agricultural production when pond sediment is discharged into aquatic recipients and used as soil fertilizer.

  19. Non-Typhoidal Salmonella Colonization in Chickens and Humans in the Mekong Delta of Vietnam.

    PubMed

    Trung, N V; Carrique-Mas, J J; Nghia, N H; Tu, L T P; Mai, H H; Tuyen, H T; Campbell, J; Nhung, N T; Nhung, H N; Minh, P V; Chieu, T T B; Hieu, T Q; Mai, N T N; Baker, S; Wagenaar, J A; Hoa, N T; Schultsz, C

    2017-03-01

    Salmonellosis is a public health concern in both the developed and developing countries. Although the majority of human non-typhoidal Salmonella enterica (NTS) cases are the result of foodborne infections or person-to-person transmission, NTS infections may also be acquired by environmental and occupational exposure to animals. While a considerable number of studies have investigated the presence of NTS in farm animals and meat/carcasses, very few studies have investigated the risk of NTS colonization in humans as a result of direct animal exposure. We investigated asymptomatic NTS colonization in 204 backyard chicken farms, 204 farmers and 306 matched individuals not exposed to chicken farming, in southern Vietnam. Pooled chicken faeces, collected using boot or handheld swabs on backyard chicken farms, and rectal swabs from human participants were tested. NTS colonization prevalence was 45.6%, 4.4% and 2.6% for chicken farms, farmers and unexposed individuals, respectively. Our study observed a higher prevalence of NTS colonization among chicken farmers (4.4%) compared with age-, sex- and location- matched rural and urban individuals not exposed to chickens (2.9% and 2.0%). A total of 164 chicken NTS strains and 17 human NTS strains were isolated, and 28 serovars were identified. Salmonella Weltevreden was the predominant serovar in both chickens and humans. NTS isolates showed resistance (20-40%) against tetracycline, chloramphenicol, sulfamethoxazole-trimethoprim and ampicillin. Our study reflects the epidemiology of NTS colonization in chickens and humans in the Mekong delta of Vietnam and emphasizes the need of larger, preferably longitudinal studies to study the transmission dynamics of NTS between and within animal and human host populations.

  20. Bartonella species and trombiculid mites of rats from the Mekong Delta of Vietnam.

    PubMed

    Loan, Hoang Kim; Cuong, Nguyen Van; Takhampunya, Ratree; Klangthong, Kewalin; Osikowicz, Lynn; Kiet, Bach Tuan; Campbell, James; Bryant, Juliet; Promstaporn, Sommai; Kosoy, Michael; Hoang, Nguyen Van; Morand, Serge; Chaval, Yannick; Hien, Vo Be; Carrique-Mas, Juan

    2015-01-01

    A survey of Bartonella spp. from 275 rats purchased in food markets (n=150) and trapped in different ecosystems (rice field, forest, and animal farms) (n=125) was carried out during October, 2012-March, 2013, in the Mekong Delta of Vietnam. The overall Bartonella spp. prevalence detected by culture and PCR in blood was 14.9% (10.7-19.1%), the highest corresponding to Rattus tanezumi (49.2%), followed by Rattus norvegicus (20.7%). Trapped rats were also investigated for the presence and type of chiggers (larvae of trombiculid mites), and Bartonella spp. were investigated on chigger pools collected from each rat by RT-PCR. A total of five Bartonella spp. were identified in rats, three of which (B. elizabethae, B. rattimassiliensis, and B. tribocorum) are known zoonotic pathogens. Among trapped rats, factors independently associated with increased prevalence of Bartonella spp. included: (1) Rat species (R. tanezumi); (2) the number of Trombiculini-Blankaartia and Schoengastiini-Ascoschoengastia mites found on rats; and (3) the habitat of the rat (i.e., forest/fields vs. animal farms). The prevalence of Bartonella infection among chiggers from Bartonella spp.-positive R. tanezumi rats was 5/25 (25%), compared with 1/27 (3.7%) among Bartonella spp.-negative R. tanezumi rats (relative risk [RR]=5.4, 95% confidence interval [CI] 0.68-43.09). The finding of Bartonella spp.-positive chiggers on Bartonella spp.-negative rats is strongly suggestive of a transovarial transmission cycle. Rats are ubiquitous in areas of human activity and farms in the Mekong Delta; in addition, trapping and trading of rats for food is common. To correctly assess the human risks due to rat trapping, marketing, and carcass dressing, further studies are needed to establish the routes of transmission and cycle of infection. The widespread presence of these zoonotic pathogens in rats and the abundance of human-rat interactions suggest that surveillance efforts should be enhanced to detect any human

  1. Modern sedimentation and morphology of the subaqueous Mekong Delta, Southern Vietnam

    NASA Astrophysics Data System (ADS)

    Unverricht, Daniel; Szczuciński, Witold; Stattegger, Karl; Jagodziński, Robert; Le, Xuan Thuyen; Kwong, Laval Liong Wee

    2013-11-01

    The Mekong River Delta is among the Asian mega-deltas and is influenced by various factors including tides (meso-tidal system), waves, coastal currents, monsoon-driven river discharge and human impact (agriculture, fishing, sand dredging, tourism). The present study aims to document the seafloor relief, sediment distribution and sediment accumulation rates to interpret modern sediment transport directions and main sedimentation processes in the subaqueous Mekong Delta. The major results of this investigation include the detection of two delta fronts 200 km apart, one at the mouth of the Bassac River (the biggest branch of the Mekong Delta) and the other around Cape Ca Mau (most south-western end of the Mekong Delta). Additionally, a large channel system runs in the subaqueous delta platform parallel to the shore and between the two fronts. The sediment accumulation rates vary greatly according to the location in the subaqueous delta and have reached up to 10 cm/yr for the last century. A cluster analysis of surface sediment samples revealed two different sediment types within the delta including a well-sorted sandy sediment and a poorly sorted, silty sediment. In addition, a third end member with medium to coarse sand characterised the distant parts of the delta at the transition to the open shelf. The increase of organic matter and carbonate content to the bottom set area and other sedimentary features such as shell fragments, foraminiferas and concretions of palaeo-soils that do not occur in delta sediments, supported grain size-based classification. Beginning in front of the Bassac River mouth, sedimentary pattern indicates clockwise sediment transport alongshore in the western direction to a broad topset area and the delta front around Cape Ca Mau. Our results clearly show the large lateral variability of the subaqueous Mekong Delta that is further complicated by strong monsoon-driven seasonality. River, tidal and wave forcing vary at local and seasonal scales

  2. Suspended sediment dynamics during the inter-monsoon season in the subaqueous Mekong Delta and adjacent shelf, southern Vietnam

    NASA Astrophysics Data System (ADS)

    Unverricht, Daniel; Nguyen, Thanh Cong; Heinrich, Christoph; Szczuciński, Witold; Lahajnar, Niko; Stattegger, Karl

    2014-01-01

    Land-ocean interactions in the coastal zone are severely influenced by tidal processes. In regions of high sediment discharge like the Mekong River Delta in southern Vietnam, these processes are even more significant. Three cruises in 2006, 2007 and 2008 were carried out to investigate the sediment suspension and their spatial distribution. Additionally, we investigated the influence of the tidal currents in relation to the suspended sediment. Therefore, all cruises took place during the inter-monsoon season between March and May where wave and wind influences are not dominant in contrast to the summer monsoon (May to early October) and winter monsoon season (November to early March).Suspended sediment concentrations (SSCs) in the particle-size range between 2.5 and 500 μm were measured with an LISST-instrument (Laser In Situ Scattering and Transmissiometry). Current velocities and directions were recorded with an Acoustic Doppler Current Profiler (ADCP). Additionally, data of different tidal gauge stations in the Mekong River Delta were correlated and compared to the mixed semidiurnal-diurnal tidal cycle.Our results show significant areas of SSCs greater than 25 μl/l in the Mekong River branches and its subaqueous delta during the inter-monsoon season. 20% of all measured SSCs in the subaqueous Mekong Delta exceed 100 μl/l. Highest concentrations occur close to the seabed. SSCs decrease at the transition to the open shelf. The shelf region contains only low suspension loads, especially on the south-eastern shelf (99% of all samples <25 μl/l). However, in the southern shelf region around Ca Mau Cape the suspension load is also higher (>25 μl/l) close to the seabed in water depths of 20-25 m.Two surveys lasting 25 h each were performed on mooring stations in 12 m (Mooring 1) and 26 m (Mooring 2) water depth and located 3.2 km apart on the subaqueous delta slope.Similar patterns of SSC over time show that concentrations of suspension load correlate with the

  3. Estimation of nitrogen and phosphorus in effluent from the striped catfish farming sector in the Mekong Delta, Vietnam.

    PubMed

    De Silva, Sena S; Ingram, Brett A; Nguyen, Phuong T; Bui, Tam M; Gooley, Geoff J; Turchini, Giovanni M

    2010-11-01

    In this study an attempt is made to estimate nitrogen and phosphorus discharged to the environment from the striped catfish (Pangasianodon hypophthalmus) farming sector in the Mekong Delta (8 degrees 33'-10 degrees 55' N, 104 degrees 30'-106 degrees 50' E), South Vietnam. The sector accounted for 687,000 t production in 2007 and 1,094,879 t in 2008, with over 95% of the produce destined for export to over 100 countries. Commercial and farm-made feeds are used in catfish farming, currently the former being more predominant. Nitrogen discharge levels were similar for commercial feeds (median 46.0 kg/t fish) and farm-made feeds (median 46.8 kg/t fish); whilst, phosphorus discharge levels for commercial feeds (median 14.4 kg/t fish) were considerably lower than for farm-made feeds (median 18.4 kg/t fish). Based on the median nutrient discharge levels for commercial feeds, striped catfish production in the Mekong Delta discharged 31,602 t N and 9,893 t P, and 50,364 t N and 15,766 t P in 2007 and 2008, respectively. However, the amount of nutrients returned directly to the Mekong River may be substantially less than this as a significant proportion of the water used for catfish farming as well as the sludge is diverted to other agricultural farming systems. Striped catfish farming in the Mekong Delta compared favourably with other cultured species, irrespective of the type of feed used, when the total amounts of N and P discharged in the production of a tonne of production was estimated.

  4. Regional-Scale Controls on Arsenic Contamination in the Multi-Aquifer System of the Mekong Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Erban, L.; Gorelick, S.; Fendorf, S. E.

    2014-12-01

    Geogenic groundwater arsenic poses a considerable health threat to a large, largely agrarian population in the Mekong Delta, Vietnam. Demand for groundwater continues to rise despite limited information about where arsenic contamination occurs and how it may be affected by excessive pumping. We investigate arsenic measurements from over >40,000 wells found throughout the Delta's seven major exploited aquifers, relating trends in contamination to ancillary physico-chemical datasets. Logistic regression modeling shows that among wells in the most shallow aquifers, arsenic occurrence above the WHO standard (10 µg/L) is best described by a well's distance to 1) the Mekong River network and 2) delta front, its depth and location within fault-bounded areas of the delta. The shallow model is inadequate to capture contaminant occurrence in deeper aquifers (generally 200-500m) where wells are rarely contaminated except in near-river areas undergoing heavy pumping. Our results are the first to quantify how the probability of arsenic contamination varies in 3D throughout the complex aquifer system in relation to both natural and anthropogenically-mediated factors, and suggest that excessive extraction may be degrading the quality of deep aquifers. Findings may serve as a baseline for managing groundwater use for optimal human welfare and assessing any future changes in arsenic occurrence.

  5. Intraspecific diversity of Edwardsiella ictaluri isolates from diseased freshwater catfish, Pangasianodon hypophthalmus (Sauvage), cultured in the Mekong Delta, Vietnam.

    PubMed

    Bartie, K L; Austin, F W; Diab, A; Dickson, C; Dung, T T; Giacomini, M; Crumlish, M

    2012-09-01

    A molecular epidemiology study was conducted on 90 Edwardsiella ictaluri isolates recovered from diseased farmed freshwater catfish, Pangasianodon hypophthalmus, cultured in the Mekong Delta, Vietnam. Thirteen isolates of E. ictaluri derived from diseased channel catfish, Ictalurus punctatus, cultured in the USA were included for comparison. All the E.ictaluri isolates tested were found to be biochemically indistinguishable. A repetitive (rep)-PCR using the single (GTG)(5) primer was shown to possess limited discriminatory power, yielding two similar DNA profiles categorized as (GTG)(5) -PCR group 1 or 2 among the Vietnam isolates and (GTG)(5) -PCR group 1 within the USA isolates. Macrorestriction analysis identified 14 and 22 unique pulsotypes by XbaI and SpeI, respectively, among a subset of 59 E. ictaluri isolates. Numerical analysis of the combined macrorestriction profiles revealed three main groups: a distinct cluster formed exclusively of the USA isolates, and a major and minor cluster with outliers contained the Vietnam isolates. Antibiotic susceptibility and plasmid profiling supported the existence of the three groups. The results indicate that macrorestriction analysis may be regarded as a suitable typing method among the E. ictaluri species of limited intraspecific diversity. Furthermore, the findings suggest that E. ictaluri originating from Vietnam may constitute a distinct genetic group.

  6. Vietnam and the sustainable development of the Mekong river basis.

    PubMed

    Quang, Nguyen Nhan

    2002-01-01

    Vietnam is a riparian country located in most downstream area of the Mekong river basin which is also shared by other states namely China, Myanmar, Laos, Thailand and Cambodia. While the Central Highlands of Vietnam has a great potential for hydropower development in tributaries of Mekong river, the Mekong delta in Vietnam territory is rich in natural resources which are favorable for agricultural development. However, besides local constraints which being gradually remedied by Vietnam, the development of the Mekong delta is subject to, in both terms of quantity and quality, availability of water resources which relates to the water use of or discharge into the river of upper riparians. With a view to co-developing these resources in a sustainable and mutually beneficial manner, Vietnam has cooperated with other states through framework of the Mekong River Commission set up by the 1995 Mekong Agreement. This paper describes the strategy and action plan applied by Viet Nam National Mekong Committee to reach the sustainable development of the Mekong river basin in general and of Vietnam parts located in the Mekong basin in particular.

  7. Release of arsenic to deep groundwater in the Mekong Delta, Vietnam, linked to pumping-induced land subsidence

    PubMed Central

    Erban, Laura E.; Gorelick, Steven M.; Zebker, Howard A.; Fendorf, Scott

    2013-01-01

    Deep aquifers in South and Southeast Asia are increasingly exploited as presumed sources of pathogen- and arsenic-free water, although little is known of the processes that may compromise their long-term viability. We analyze a large area (>1,000 km2) of the Mekong Delta, Vietnam, in which arsenic is found pervasively in deep, Pliocene–Miocene-age aquifers, where nearly 900 wells at depths of 200–500 m are contaminated. There, intensive groundwater extraction is causing land subsidence of up to 3 cm/y as measured using satellite-based radar images from 2007 to 2010 and consistent with transient 3D aquifer simulations showing similar subsidence rates and total subsidence of up to 27 cm since 1988. We propose a previously unrecognized mechanism in which deep groundwater extraction is causing interbedded clays to compact and expel water containing dissolved arsenic or arsenic-mobilizing solutes (e.g., dissolved organic carbon and competing ions) to deep aquifers over decades. The implication for the broader Mekong Delta region, and potentially others like it across Asia, is that deep, untreated groundwater will not necessarily remain a safe source of drinking water. PMID:23918360

  8. Prevalence of risk factors for non-communicable diseases in the Mekong Delta, Vietnam: results from a STEPS survey

    PubMed Central

    2009-01-01

    Background Despite the increasing burden of non-communicable diseases (NCD) in Vietnam, information on the prevalence of preventable risk factors for NCD is restricted to the main urban centres of Ha Noi, and Ho Chi Minh City (HCMC). This population-based survey aimed to describe the prevalence of risk factors for NCD in a rural Vietnamese sample. Methods This survey was conducted using the WHO "STEPwise approach to surveillance of non-communicable diseases" (STEPS) methodology. Participants (n = 1978) were residents of the Mekong Delta region selected by multi-stage sampling. Standardised international protocols were used to measure behavioural risk factors (smoking, alcohol consumption, fruit and vegetable consumption, physical activity), physical characteristics (weight, height, waist and hip circumferences, blood pressure – BP), fasting blood glucose (BG) and total cholesterol (TC). Data were analysed using complex survey analysis methods. Results In this sample, 8.8% of men and 12.6% of women were overweight (body mass index (BMI) ≥ 25 kg/m2) and 2.3% of men and 1.5% of women were obese (BMI ≥ 30 kg/m2). The prevalence of hypertension (systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg, or taking medication for hypertension) was 27.3% for men and 16.2% for women. There were 1.0% of men and 1.1% of women with raised BG (defined as capillary whole BG of at least 6.1 mmol/L). Conclusion We provide the first NCD risk factor profile of people living in the Mekong Delta of Vietnam using standardised methodology. Our findings for this predominantly rural sample differ from previous studies conducted in Ha Noi and HCMC, and suggest that it is inappropriate to generalise findings from the big-city surveys to the other 80% of the population. PMID:19671195

  9. Pesticide management and their residues in sediments and surface and drinking water in the Mekong Delta, Vietnam.

    PubMed

    Toan, Pham Van; Sebesvari, Zita; Bläsing, Melanie; Rosendahl, Ingrid; Renaud, Fabrice G

    2013-05-01

    Public concern in Vietnam is increasing with respect to pesticide pollution of the environment and of drinking water resources. While established monitoring programs in the Mekong Delta (MD) focus on the analysis of organochlorines and some organophosphates, the environmental concentrations of more recently used pesticides such as carbamates, pyrethroides, and triazoles are not monitored. In the present study, household level pesticide use and management was therefore surveyed and combined with a one year environmental monitoring program of thirteen relevant pesticides (buprofezin, butachlor, cypermethrin, α-endosulfan, β-endosulfan, endosulfan-sulfate, fenobucarb, fipronil, isoprothiolane, pretilachlor, profenofos, propanil, and propiconazole) in surface water, soil, and sediment samples. The surveys showed that household level pesticide management remains suboptimal in the Mekong Delta. As a consequence, a wide range of pesticide residues were present in water, soil, and sediments throughout the monitoring period. Maximum concentrations recorded were up to 11.24 μg l(-1) in water for isoprothiolane and up to 521 μg kg(-1) dm in sediment for buprofezin. Annual average concentrations ranged up to 3.34 μg l(-1) in water and up to 135 μg kg(-1) dm in sediment, both for isoprothiolane. Occurrence of pesticides in the environment throughout the year and co-occurrence of several pesticides in the samples indicate a considerable chronic exposure of biota and humans to pesticides. This has a high relevance in the delta as water for drinking is often extracted from canals and rivers by rural households (GSO, 2005, and own surveys). The treatment used by the households for preparing surface water prior to consumption (flocculation followed by boiling) is insufficient for the removal of the studied pesticides and boiling can actually increase the concentration of non-volatile pollutants.

  10. Osmoregulatory and immunological status of the pond-raised striped catfish (Pangasianodon hypophthalmus S.) as affected by seasonal runoff and salinity changes in the Mekong Delta, Vietnam.

    PubMed

    Schmitz, Mélodie; Baekelandt, Sébastien; Tran Thi, Lam Khoa; Mandiki, Syaghalirwa N M; Douxfils, Jessica; Nguyen, Thinh Quoc; Do Thi Thanh, Huong; Kestemont, Patrick

    2017-02-01

    In Vietnam, the production of striped catfish Pangasianodon hypophthalmus S. reached more than 1.2 millions of tons in 2014 and is mainly gathered in the Mekong Delta (South Vietnam). A survey was carried out during the dry season 2013 (March-April) and rainy season 2014 (July-August) in 12 fish farms of the lower (Tra Vinh Province) and higher (Can Tho Province) Mekong River Delta. This study allowed drawing up current key osmoregulatory and innate immune parameters of striped catfish in aquaculture depending on the geographical location, particularly the proximity to the River Mekong Estuary and the seasonal surface runoff. In the dry season, plasma osmolality was positively correlated with salinity. Gill Na(+)K(+) ATPase dropped in the rainy season, while kidney Na(+)K(+) ATPase remained stable. Abundance of immune blood cells, especially thrombocytes and monocytes, tended to increase in farms located in tidal area. Production of reactive oxygen species in the spleen, kidney lysozyme activity and plasma complement activity did not vary whatever the season or the proximity to the estuary. Plasma lysozyme activity was 50-fold higher than in kidney and increased in the rainy season as well as in tidal sites. Kidney complement activity decreased in the dry season, especially in tidal sites. In conclusion, regarding key osmoregulatory and immune factors, striped catfish farms located in the Mekong Delta may be affected by seasonal and regional salinity and runoff fluctuations.

  11. Discrimination rice cropping systems using multi-temporal Proba-V data in the Mekong Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Son, Nguyen-Thanh; Chen, Chi-Farn; Chen, Cheng-Ru; Chang, Ly-Yu; Chiang, Shou-Hao; Lau, Khin-Va

    2016-04-01

    Rice is considered a main source of livelihoods for several billions of people worldwide and plays an important role in the economy of many Asian countries. More than just a food source, rice production is regarded as one of the most important components to maintaining political stability and is also a national subject of economic policy due to domestic food consumption and grain exports. Vietnam is globally one of the largest rice producers and suppliers with more than 80% of the exported rice amount produced from the Mekong River Delta. This delta is one of the three deltas in the world most vulnerable to the climate change, causing the potential loss of rice yields. Thus, spatiotemporal information of rice cropping systems is important for agricultural management to ensure food security and rice grain exports. Coarse resolution satellite data such as MODIS demonstrates the applicability for rice mapping at a large scale. However, the use of MODIS data for such a monitoring purpose still reveals a challenging task due to mixed-pixel issues. The Proba-V satellite launched on 7 May 2013 is a potential candidate for this monitoring purpose because the data include four spectral bands (blue, red, near-infrared and mid-infrared) with a swath of 2,285 km with a spatial resolution of 100 m and temporal resolution of 5 days. This study aimed to investigate the applicability of multi-temporal Proba-V data for mapping rice cropping systems in Mekong Delta River, South Vietnam. The data were processed for 2014-2015 rice cropping seasons, following three main steps: (1) construction of smooth time-series NDVI data, (2) classification of rice cropping systems using crop phenological metrics, and (3) accuracy assessment of the mapping results. The results indicated that the smooth time-series NDVI profiles characterized the temporal spectral responses of rice fields through different growing stages of rice plant, which was critically important for understanding rice crop

  12. Status and changes of mangrove forest in Mekong Delta: Case study in Tra Vinh, Vietnam

    NASA Astrophysics Data System (ADS)

    Thu, Phan Minh; Populus, Jacques

    2007-01-01

    Because shrimp culture in the Mekong Delta develops rapidly, it has negatively impacted the environment, socio-economics and natural resources. In particular, mangrove forests have been altered by the shrimp culture. The area of mangrove forests in the region has been reduced and this is seen especially in Tra Vinh province. The results obtained from GIS (Geography Information System) and RS (Remote Sensing) show the status of mangrove forests in Tra Vinh province in 1965, 1995 (Northeastern part of Tra Vinh Province) and 2001. In 1965, the area of mangrove forests was 21,221 ha making up 56% of total land-use, while in 2001 it was 12,797 ha making up 37% of total land-use. Also based on GIS analysis, over the 36 years (1965-2001), the total coverage of mangrove forests have decreased by 50% since 1965. However, the speed of mangrove forest destruction in the period from 1965 to 1995 was much less than that in the period from 1995 to 2001. The average annual reduction in mangrove forest coverage in the first period (1965-1995) was 0.2% whereas it was 13.1% in the later period (1995-2001). For the long time, mangrove deforestation has been caused by war, collection of firewood and clearing for agriculture, and recently, shrimp farming has significantly contributed rate of mangrove destruction.

  13. Farmers' perceived risks of climate change and influencing factors: a study in the Mekong Delta, Vietnam.

    PubMed

    Le Dang, Hoa; Li, Elton; Nuberg, Ian; Bruwer, Johan

    2014-08-01

    Many countries are confronting climate change that threatens agricultural production and farmers' lives. Farmers' perceived risks of climate change and factors influencing those perceived risks are critical to their adaptive behavior and well-planned adaptation strategies. However, there is limited understanding of these issues. In this paper, we attempt to quantitatively measure farmers' perceived risks of climate change and explore the influences of risk experience, information, belief in climate change, and trust in public adaptation to those perceived risks. Data are from structured interviews with 598 farmers in the Mekong Delta. The study shows that perceived risks to production, physical health, and income dimensions receive greater priority while farmers pay less attention to risks to happiness and social relationships. Experiences of the events that can be attributed to climate change increase farmers' perceived risks. Information variables can increase or decrease perceived risks, depending on the sources of information. Farmers who believe that climate change is actually happening and influencing their family's lives, perceive higher risks in most dimensions. Farmers who think that climate change is not their concern but the government's, perceive lower risks to physical health, finance, and production. As to trust in public adaptation, farmers who believe that public adaptive measures are well co-ordinated, perceive lower risks to production and psychology. Interestingly, those who believe that the disaster warning system is working well, perceive higher risks to finance, production, and social relationships. Further attention is suggested for the quality, timing, and channels of information about climate change and adaptation.

  14. Farmers' Perceived Risks of Climate Change and Influencing Factors: A Study in the Mekong Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Le Dang, Hoa; Li, Elton; Nuberg, Ian; Bruwer, Johan

    2014-08-01

    Many countries are confronting climate change that threatens agricultural production and farmers' lives. Farmers' perceived risks of climate change and factors influencing those perceived risks are critical to their adaptive behavior and well-planned adaptation strategies. However, there is limited understanding of these issues. In this paper, we attempt to quantitatively measure farmers' perceived risks of climate change and explore the influences of risk experience, information, belief in climate change, and trust in public adaptation to those perceived risks. Data are from structured interviews with 598 farmers in the Mekong Delta. The study shows that perceived risks to production, physical health, and income dimensions receive greater priority while farmers pay less attention to risks to happiness and social relationships. Experiences of the events that can be attributed to climate change increase farmers' perceived risks. Information variables can increase or decrease perceived risks, depending on the sources of information. Farmers who believe that climate change is actually happening and influencing their family's lives, perceive higher risks in most dimensions. Farmers who think that climate change is not their concern but the government's, perceive lower risks to physical health, finance, and production. As to trust in public adaptation, farmers who believe that public adaptive measures are well co-ordinated, perceive lower risks to production and psychology. Interestingly, those who believe that the disaster warning system is working well, perceive higher risks to finance, production, and social relationships. Further attention is suggested for the quality, timing, and channels of information about climate change and adaptation.

  15. Effects of local and spatial conditions on the quality of harvested rainwater in the Mekong Delta, Vietnam.

    PubMed

    Wilbers, Gert-Jan; Sebesvari, Zita; Rechenburg, Andrea; Renaud, Fabrice G

    2013-11-01

    The objective of this study was to assess the quality of harvested rainwater in the Mekong Delta (MD), Vietnam for local (roof types, storage system and duration) and spatial (proximity of industry, main roads, coastline) conditions. 78 harvested rainwater samples were collected in the MD and analyzed for pH, turbidity, TDS, COD, nutrients (NH4, NO3, NO2, o-PO4), trace metals and coliforms. The results show that thatch roofs lead to an increase of pollutants like COD (max 23.2 mgl(-1)) and turbidity (max 10.1 mgl(-1)) whereas galvanized roofs lead to an increase of Zn (max 2.2 mgl(-1)). The other local and spatial parameters had no or only minor influence on the quality of household harvested rainwater. However, lead (Pb) (max. 16.9 μgl(-1)) and total coliforms (max. 102 500 CFU100 ml(-1)) were recorded at high concentrations, probably due to a variety of household-specific conditions such as rainwater storage, collection and handling practices.

  16. Simulated impacts of climate change on current farming locations of striped catfish (Pangasianodon hypophthalmus; Sauvage) in the Mekong Delta, Vietnam.

    PubMed

    Nguyen, Anh L; Dang, Vinh H; Bosma, Roel H; Verreth, Johan A J; Leemans, Rik; De Silva, Sena S

    2014-12-01

    In Vietnam, culturing striped catfish makes an important contribution to the Mekong Delta's economy. Water level rise during rainy season and salt intrusion during dry season affect the water exchange and quality for this culture. Sea level rise as a consequence of climate change will worsen these influences. In this study, water level rise and salt water intrusion for three sea level rise (SLR) scenarios (i.e., +30, +50, and +75 cm) were simulated. The results showed that at SLR +50, the 3-m-flood level would spread downstream and threaten farms located in AnGiang, DongThap and CanTho provinces. Rising salinity levels for SLR +75 would reduce the window appropriate for the culture in SocTrang and BenTre provinces, and in TienGiang's coastal districts. Next to increasing dikes to reduce the impacts, the most tenable and least disruptive option to the farming community would be to shift to a salinity tolerant strain of catfish.

  17. Rodents and risk in the Mekong Delta of Vietnam: seroprevalence of selected zoonotic viruses in rodents and humans.

    PubMed

    Van Cuong, Nguyen; Carrique-Mas, Juan; Vo Be, Hien; An, Nguyen Ngoc; Tue, Ngo Tri; Anh, Nguyet Lam; Anh, Pham Hong; Phuc, Nguyen The; Baker, Stephen; Voutilainen, Liina; Jääskeläinen, Anne; Huhtamo, Eili; Utriainen, Mira; Sironen, Tarja; Vaheri, Antti; Henttonen, Heikki; Vapalahti, Olli; Chaval, Yannick; Morand, Serge; Bryant, Juliet E

    2015-01-01

    In the Mekong Delta in southern Vietnam, rats are commonly traded in wet markets and sold live for food consumption. We investigated seroprevalence to selected groups of rodent-borne viruses among human populations with high levels of animal exposure and among co-located rodent populations. The indirect fluorescence antibody test (IFAT) was used to determine seropositivity to representative reference strains of hantaviruses (Dobrava virus [DOBV], Seoul virus [SEOV]), cowpox virus, arenaviruses (lymphocytic choriomeningitis virus [LCMV]), flaviviruses (tick-borne encephalitis virus [TBEV]), and rodent parechoviruses (Ljungan virus), using sera from 245 humans living in Dong Thap Province and 275 rodents representing the five common rodent species sold in wet markets and present in peridomestic and farm settings. Combined seropositivity to DOBV and SEOV among the rodents and humans was 6.9% (19/275) and 3.7% (9/245), respectively; 1.1% (3/275) and 4.5% (11/245) to cowpox virus; 5.4% (15/275) and 47.3% (116/245) for TBEV; and exposure to Ljungan virus was 18.8% (46/245) in humans, but 0% in rodents. Very little seroreactivity was observed to LCMV in either rodents (1/275, 0.4%) or humans (2/245, 0.8%). Molecular screening of rodent liver tissues using consensus primers for flaviviruses did not yield any amplicons, whereas molecular screening of rodent lung tissues for hantavirus yielded one hantavirus sequence (SEOV). In summary, these results indicate low to moderate levels of endemic hantavirus circulation, possible circulation of a flavivirus in rodent reservoirs, and the first available data on human exposures to parechoviruses in Vietnam. Although the current evidence suggests only limited exposure of humans to known rodent-borne diseases, further research is warranted to assess public health implications of the rodent trade.

  18. Spatial and temporal variability of surface water pollution in the Mekong Delta, Vietnam.

    PubMed

    Wilbers, Gert-Jan; Becker, Mathias; Nga, La Thi; Sebesvari, Zita; Renaud, Fabrice G

    2014-07-01

    Surface water pollution in the Vietnamese Mekong Delta (MD) could threaten human, animal and ecosystem health given the fact that this water source is intensively used for drinking, irrigation and domestic services. We therefore determined the levels of pollution by organic pollutants, salts, metals and microbial indicators by (bi)monthly monitoring of canals between November 2011 and July 2012 at 32 sampling locations, representing fresh and saline/brackish environments. The results were compared with national water quality guidelines, between the studied regions and with water quality data from main waterways. Key factors explaining the observed levels of pollution in surface water were identified through principal component analysis (PCA). Temporal variations due to tidal regime and seasonality were also assessed. Based on regression models, the spatial variability of five water quality parameters was visualized using GIS based maps. Results indicate that pH (max. 8.6), turbidity (max. 461 FTU), maximum concentrations of ammonium (14.7 mg L(-1)), arsenic (44.1 μg L(-1)), barium (157.5 μg L(-1)), chromium (84.7 μg L(-1)), mercury (45.5 μg L(-1)), manganese (1659.7 μg L(-1)), aluminum (14.5 mg L(-1)), iron (17.0 mg L(-1)) and the number of Escherichia coli (87,000 CFU 100 mL(-1)) and total coliforms (2,500,000 CFU 100 mL(-1)) in canals exceed the thresholds set by Vietnamese quality guidelines for drinking and domestic purposes. The PCA showed that i) urbanization; ii) metal leaching from soils; iii) aquaculture; and iv) tidal regime explain 85% of the variance of surface water quality attributes. Significant differences in water quality were found due to daily tidal regime and as a result of seasonality. Surface water quality maps for dissolved oxygen, ammonium, ortho-phosphate, manganese and total coliforms were developed to highlight hot-spot areas of pollution. The results of this study can assist policy makers in developing water management strategies

  19. Effects of chlorpyrifos ethyl on acetylcholinesterase activity in climbing perch cultured in rice fields in the Mekong Delta, Vietnam.

    PubMed

    Nguyen, Tam Thanh; Berg, Håkan; Nguyen, Hang Thi Thuy; Nguyen, Cong Van

    2015-07-01

    Climbing perch is commonly harvested in rice fields and associated wetlands in the Mekong Delta. Despite its importance in providing food and income to local households, there is little information how this fish species is affected by the high use of pesticides in rice farming. Organophosphate insecticides, such as chlorpyrifos ethyl, which are highly toxic to aquatic organisms, are commonly used in the Mekong Delta. This study shows that the brain acetylcholinesterase (AChE) activity in climbing perch fingerlings cultured in rice fields, was significantly inhibited by a single application of chlorpyrifos ethyl, at doses commonly applied by rice farmers (0.32-0.64 kg/ha). The water concentration of chlorpyrifos ethyl decreased below the detection level within 3 days, but the inhibition of brain AChE activity remained for more than 12 days. In addition, the chlorpyrifos ethyl treatments had a significant impact on the survival and growth rates of climbing perch fingerlings, which were proportional to the exposure levels. The results indicate that the high use of pesticides among rice farmers in the Mekong Delta could have a negative impact on aquatic organisms and fish yields, with implications for the aquatic biodiversity, local people's livelihoods and the aquaculture industry in the Mekong Delta.

  20. Early Holocene initiation of the Mekong River delta, Vietnam, and the response to Holocene sea-level changes detected from DT1 core analyses

    NASA Astrophysics Data System (ADS)

    Nguyen, Van Lap; Ta, Thi Kim Oanh; Saito, Yoshiki

    The Early Holocene initiation of the Mekong River delta, Vietnam, was investigated based on sedimentary facies, microfossil analyses, and radiocarbon dating of DT1 core taken from the upper delta plain. The DT1 core (105°38'51″E, 10°17'02″N, elevation + 2 m) is 51.5 m long and located in fill of a buried incised valley. This incised valley of the Paleo-Mekong River formed during the last glacial maximum, which is 20-30 km wide, has been traced spatially from the Cambodian border to the South China Sea coast by compilation of existing core data. The DT1 core records the history of the estuarine channel and delta systems of the Mekong River during the early to middle Holocene. The sedimentary facies, determined particularly from sedimentary structures, diatom and foraminifera assemblages, grain-size variation, and the accumulation rate, clearly show an upward-deepening succession in the lower part of the core from marsh or intertidal flat to subtidal-inner bay facies and an overlying upward-shallowing succession from prodelta to intertidal flat-floodplain. The boundary between the two successions, indicating the maximum flooding surface, occurred at approximately 8.0 ka, at the time that the Mekong River delta was initiated. The delta initiation and sediment facies succession are closely linked to Holocene sea-level changes, particularly a standstill from 8.0 to 7.5 ka after a rapid rise of sea level from 8.8 to 8.2 ka. During the further sea-level rise from 7.5 to 7.0 ka, sediments aggraded, forming topset sedimentary deposits.

  1. Contamination by polybrominated diphenyl ethers and persistent organochlorines in catfish and feed from Mekong River Delta, Vietnam.

    PubMed

    Minh, Nguyen Hung; Minh, Tu Binh; Kajiwara, Natsuko; Kunisue, Tatsuya; Iwata, Hisato; Viet, Pham Hung; Tu, Nguyen Phuc Cam; Tuyen, But Cach; Tanabe, Shinsuke

    2006-10-01

    Commercial feeds for aquaculture and catfish samples were collected from the Mekong River Delta, Vietnam, for determination of polybrominated diphenyl ethers (PBDEs) and selected persistent organochlorines, including polychlorinated biphenyls (PCBs), DDT and its metabolites (DDTs), chlordane-related compounds (CHLs), hexachlorocyclohexane isomers (HCHs), and hexachlorobenzene (HCB). The most abundant contaminants were DDTs, with concentrations ranging from 10 to 700 ng/g lipid weight, followed by PCBs (1.0-80 ng/g), CHLs (<0.01-8.2 ng/g), PBDEs (0.12-3.7 ng/g), HCHs (<0.03-5.1 ng/g), and HCB (<0.07-3.2 ng/g). Polybrominated diphenyl ethers were detected in all samples, suggesting their widespread contamination in the region. However, PBDE contamination levels in the present catfish specimens were low in comparison to levels worldwide. Interestingly, residue levels of all the contaminants were significantly higher in catfish collected near a municipal dumping site compared to farmed catfish. This suggests that runoffs from the dumping site during floods and rains may have brought pollutants to the surrounding areas. Contamination pattern in aquaculture feeds revealed elevated levels of PCBs and PBDEs in samples from foreign companies, perhaps implying their higher residues in some imported ingredients. Congener profiles of PBDEs and PCBs demonstrated similarity between the farmed catfish and the aquaculture feeds, suggesting these feeds as a major source of pollution to the farmed catfish. On the other hand, the PBDE and PCB profiles in the dumpsite catfish are clearly different from those of the farmed catfish, revealing their exposure to different sources. Risk assessment showed significantly higher intake of the contaminants by people who eat catfish cultured near the dumping areas. Further investigation regarding fate and occurrence of the contaminants in dumping sites is necessary.

  2. Establishing river basin organisations inVietnam: Red River, Dong Nai River and Lower Mekong Delta.

    PubMed

    Taylor, P; Wright, G

    2001-01-01

    River basin management is receiving considerable attention at present. Part of the debate, now occurring worldwide, concerns the nature of the organisations that are required to manage river basins successfully, and whether special-purpose river basin organisations (RBOs) are always necessary and in what circumstance they are likely to (i) add to the management of the water resources and (ii) be successful. The development of river basin management requires a number of important elements to be developed to a point where the river basin can be managed successfully. These include the relevant laws, the public and non-government institutions, the technical capabilities of the people, the understanding and motivation of people, and the technical capacity and systems, including information. A river basin organisation (or RBO) is taken to mean a special-purpose organisation charged with some part of the management of the water resources of a particular river basin. Generally speaking, such organisations are responsible for various functions related to the supply, distribution, protection and allocation of water, and their boundaries follow the watershed of the river in question. However, the same functions can be carried out by various organisations, which are not configured on the geographical boundaries of a river basin. This paper outlines recent work on river basin organisation in Vietnam, and makes some comparisons with the situation in Australia.

  3. Temporal and spatial analysis of hand, foot, and mouth disease in relation to climate factors: A study in the Mekong Delta region, Vietnam.

    PubMed

    Nguyen, Huong Xuan; Chu, Cordia; Nguyen, Huong Lien Thi; Nguyen, Ha Thanh; Do, Cuong Manh; Rutherford, Shannon; Phung, Dung

    2017-03-01

    This study examined the temporal and spatial patterns of hand, foot, and mouth disease (HFMD) in the Mekong Delta region in Vietnam. A time-series analysis was used to examine the temporal patterns of HFMD in relation to climate factors while a retrospective space-time scan was used to detect the high-risk space-time clusters of this disease. A 1°C increase in average temperature was associated with 5.6% increase in HFMD rate at lag 5days (95% CI 0.3-10.9). A 1% increase in humidity had equal influence of 1.7% increases on HFMD rate at both lag 3days and 6days (95% CI 0.7-2.7 and 95% CI 0.8-2.6, respectively). An increase in 1 unit of rainfall was associated with a 0.5% increase of HFMD rate on the lag 1 and 6days (95% CI 0.2-0.9 and 95% CI 0.1-0.8, respectively). The predictive model indicated that the peak of HFMD was from October to December - the rainy season in the Mekong Delta region. Most high-risk clusters were located in areas with high population density and close to transport routes. The findings suggest that HFMD is influenced by climate factors and is likely to increase in the future due to climate change related weather events.

  4. Combined fluvial and pluvial urban flood hazard analysis: concept development and application to Can Tho city, Mekong Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Apel, Heiko; Martínez Trepat, Oriol; Nghia Hung, Nguyen; Thi Chinh, Do; Merz, Bruno; Viet Dung, Nguyen

    2016-04-01

    Many urban areas experience both fluvial and pluvial floods, because locations next to rivers are preferred settlement areas and the predominantly sealed urban surface prevents infiltration and facilitates surface inundation. The latter problem is enhanced in cities with insufficient or non-existent sewer systems. While there are a number of approaches to analyse either a fluvial or pluvial flood hazard, studies of a combined fluvial and pluvial flood hazard are hardly available. Thus this study aims to analyse a fluvial and a pluvial flood hazard individually, but also to develop a method for the analysis of a combined pluvial and fluvial flood hazard. This combined fluvial-pluvial flood hazard analysis is performed taking Can Tho city, the largest city in the Vietnamese part of the Mekong Delta, as an example. In this tropical environment the annual monsoon triggered floods of the Mekong River, which can coincide with heavy local convective precipitation events, causing both fluvial and pluvial flooding at the same time. The fluvial flood hazard was estimated with a copula-based bivariate extreme value statistic for the gauge Kratie at the upper boundary of the Mekong Delta and a large-scale hydrodynamic model of the Mekong Delta. This provided the boundaries for 2-dimensional hydrodynamic inundation simulation for Can Tho city. The pluvial hazard was estimated by a peak-over-threshold frequency estimation based on local rain gauge data and a stochastic rainstorm generator. Inundation for all flood scenarios was simulated by a 2-dimensional hydrodynamic model implemented on a Graphics Processing Unit (GPU) for time-efficient flood propagation modelling. The combined fluvial-pluvial flood scenarios were derived by adding rainstorms to the fluvial flood events during the highest fluvial water levels. The probabilities of occurrence of the combined events were determined assuming independence of the two flood types and taking the seasonality and probability of

  5. Assimilation of MODIS-derived LAI by radiative transfer modelling to crop growth simulation model for rice crop monitoring and yield estimation in the Mekong delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Nguyen, H.; de Bie, K.; Verhoef, W.

    2014-12-01

    Successful monitoring of rice crops and estimation of its yields in Mekong delta provide vital information to government agencies, rice production stakeholders and insurance companies in making their decisions and plans to establish solutions to protect rice smallholders from the risks involved. Remote sensing-based information promises a cost-effective way to observe rice crop growth in the largest rice producing region of Vietnam. For an extensive rice cultivation region as the Mekong delta, the use of divergence statistic to extract information from long-term or hypertemporal optical remote sensing NDVI profile to map rice cropping patterns has shown a high degree of success. The result map provides accurate information on where rice grew, when it was seeded and harvested, how many time it was cultivated every year. In addition, by using 8-day MODIS TERRA surface reflectance in Soil-Leaf-Canopy (SLC) radiative transfer model, 70 percent variation of seasonal rice LAI values was able to capture, making it useful to be assimilated into a rice crop growth simulation model (ORYZA 2000) to estimate the regional rice production in the season of 2008-2009. Tested results from 56 rice fields located in different rice cropping patterns showed that yields estimated using ORYZA2000 can explain 83 percent variation of field measured yields. However, simulated yields by ORYZA 2000 were used to overestimate by the model since some of model parameters could not be recalibrated due to the lack of field experiment data. This suggest that in the future, in order to gain a better results of rice crop monitoring and yield estimation, apart from improving the estimation of MODIS -derived LAIs by using SLC, calibrating crop growth simulation's parameter have to be taken into account.

  6. Effective management for acidic pollution in the canal network of the Mekong Delta of Vietnam: a modeling approach.

    PubMed

    Phong, Ngo Dang; Hoanh, Chu Thai; Tuong, To Phuc; Malano, Hector

    2014-07-01

    Acidic pollution can cause severe environmental consequences annually in coastal areas overlain with acid sulfate soils (ASS). A water quality model was used as an analytical tool for exploring the effects of water management options and other interventions on acidic pollution and salinity in Bac Lieu, a coastal province of the Mekong Delta. Fifty eight percent of the provincial area is covered by ASS, and more than three-fourths (approximately 175,000 ha) are used for brackish-water shrimp culture. Simulations of acid water propagation in the canal network indicate that the combination of opening the two main sluices along the East Sea of the study area at high tide for one day every week in May and June and widening the canals that connect these sluices to the West Sea allows for adequate saline water intake and minimizes the acidic pollution in the study area. On the other hand, canal dredging in the freshwater ASS area should be done properly as it can create severe acidic pollution.

  7. An extensive ground monitoring system for floodplain inundation: the WISDOM test area Tam Nong in the Mekong Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Hung, N. N.; Thoss, H.; Güntner, A.; Apel, H.

    2009-04-01

    Monitoring of floodplain inundation is one of the key issues in respect to hydraulic model calibration, especially for 2-dimensional modeling of floodplains. While in recent years the use of remote sensing products for flood mapping have received a large boost by new techniques and platforms (LiDAR, SAR, optical system, both satellite and airborn) and proved to be a significant step forward in floodplain inundation model calibration, they are not the encompassing answer to the chronic lack of data of floodplain inundation. Due to the singular nature of floods and restrictions in sensor availability, overpass frequencies, unfavorable atmospheric conditions and difficulties in signal interpretation, remote sensing products usually provide only a short but spatially extensive view on the inundation process. In order to get a more encompassing picture of the inundation dynamics, time series of flood parameters have to be collected in the floodplains itself. In order to overcome the intrinsic problem of testing flood monitoring equipment in a short termed research project, an extensive ground-based flood monitoring system was established within the WISDOM (www.wisdom.caf.dlr.de)project in the Mekong Delta. Due to annual flood rhythm flood condition could be guaranteed within the projects duration. For the flood season 2008 the test site Tam Nong in the Plain of Reeds in the Delta was equipped with 21 water level pressure gauges, 7 turbidity sensors and 2 GPS buoys, all designed to run autonomously for a period of 6 month and sampling data in short termed intervals. The collected data show a detailed picture of the inundation and sediment dynamics in the whole area including tidal influence and dike overtopping. This unique data set will be used in combination with spatial explicit water masks derived by remote sensing for 2D hydraulic model calibration in the next step.

  8. Earthworms of the 'acaecate' Pheretima group in Vietnam (Oligochaeta: Megascolecidae), with description of a new species from the Mekong delta.

    PubMed

    Nguyen, Tung T; Tran, Binh T T; Nguyen, Anh D

    2014-09-22

    The 'acaecate' Pheretima group from Vietnam is revised, with description of a new species, Polypheretima mekongmontis sp. nov. A total of 18 species of three genera, Metapheretima Michaelsen, 1928, Planapheretima Michaelsen, 1934, and Polypheretima Michaelsen, 1934 has been recorded from Vietnam. Caecate species of Planapheretima are included here as well. Planapheretima arboricola (Rosa, 1890), Pl. lacertina (Chen, 1946), Pl. tenebrica (Chen, 1946), Polypheretima elongata (Perrier, 1872), and Po. taprobanae (Beddard, 1892) are originally recorded from other countries; all remaining species are native to Vietnam. The species Polypheretima tani (Thai, 1996) and Po. tiencanhensis (Pham, 1995) are transferred to the genus Metapheretima. A key to species and distribution maps are also presented.

  9. Temporal and spatial assessment of river surface water quality using multivariate statistical techniques: a study in Can Tho City, a Mekong Delta area, Vietnam.

    PubMed

    Phung, Dung; Huang, Cunrui; Rutherford, Shannon; Dwirahmadi, Febi; Chu, Cordia; Wang, Xiaoming; Nguyen, Minh; Nguyen, Nga Huy; Do, Cuong Manh; Nguyen, Trung Hieu; Dinh, Tuan Anh Diep

    2015-05-01

    The present study is an evaluation of temporal/spatial variations of surface water quality using multivariate statistical techniques, comprising cluster analysis (CA), principal component analysis (PCA), factor analysis (FA) and discriminant analysis (DA). Eleven water quality parameters were monitored at 38 different sites in Can Tho City, a Mekong Delta area of Vietnam from 2008 to 2012. Hierarchical cluster analysis grouped the 38 sampling sites into three clusters, representing mixed urban-rural areas, agricultural areas and industrial zone. FA/PCA resulted in three latent factors for the entire research location, three for cluster 1, four for cluster 2, and four for cluster 3 explaining 60, 60.2, 80.9, and 70% of the total variance in the respective water quality. The varifactors from FA indicated that the parameters responsible for water quality variations are related to erosion from disturbed land or inflow of effluent from sewage plants and industry, discharges from wastewater treatment plants and domestic wastewater, agricultural activities and industrial effluents, and contamination by sewage waste with faecal coliform bacteria through sewer and septic systems. Discriminant analysis (DA) revealed that nephelometric turbidity units (NTU), chemical oxygen demand (COD) and NH₃ are the discriminating parameters in space, affording 67% correct assignation in spatial analysis; pH and NO₂ are the discriminating parameters according to season, assigning approximately 60% of cases correctly. The findings suggest a possible revised sampling strategy that can reduce the number of sampling sites and the indicator parameters responsible for large variations in water quality. This study demonstrates the usefulness of multivariate statistical techniques for evaluation of temporal/spatial variations in water quality assessment and management.

  10. A hydrological model for interprovincial water resource planning and management: A case study in the Long Xuyen Quadrangle, Mekong Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Hanington, Peter; To, Quang Toan; Van, Pham Dang Tri; Doan, Ngoc Anh Vu; Kiem, Anthony S.

    2017-04-01

    In this paper we present the results of the development and calibration of a fine-scaled quasi-2D hydrodynamic model (IWRM-LXQ) for the Long Xuyen Quadrangle - an important interprovincial agricultural region in the Vietnamese Mekong Delta. We use the Long Xuyen Quadrangle as a case study to highlight the need for further investment in hydrodynamic modelling at scales relevant to the decisions facing water resource managers and planners in the Vietnamese Mekong Delta. The IWRM-LXQ was calibrated using existing data from a low flood year (2010) and high flood year (2011), including dry season and wet season flows. The model performed well in simulating low flood and high flood events in both dry and wet seasons where good spatial and temporal data exists. However, our study shows that there are data quality issues and key data gaps that need to be addressed before the model can be further refined, validated and then used for decision making. The development of the IWRM-LXQ is timely, as significant investments in land and water resource development and infrastructure are in planning for the Vietnamese Mekong Delta. In order to define the scope of such investments and their feasibility, models such as the IWRM-LXQ are an essential tool to provide objective assessment of investment options and build stakeholder consensus around potentially contentious development decisions.

  11. Molecular characterization of antibiotic resistance in Pseudomonas and Aeromonas isolates from catfish of the Mekong Delta, Vietnam.

    PubMed

    Nguyen, Hoang Nam Kha; Van, Thi Thu Hao; Nguyen, Huu Thinh; Smooker, Peter M; Shimeta, Jeff; Coloe, Peter J

    2014-07-16

    A collection of 116 motile Pseudomonas spp. and 92 Aeromonas spp. isolated from 15 Vietnamese intensive catfish farms was analyzed to examine the molecular antibiotic resistance characteristics and the transferability of resistance markers within and between species. High levels of resistance to ampicillin, trimethoprim/sulfamethoxazole, nalidixic acid, chloramphenicol, and nitrofurantoin were observed. The percentage of multiple drug resistance of Pseudomonas spp. and Aeromonas spp. isolates was 96.6% and 61.9%, respectively. The multiple antibiotic resistance (MAR) index mean values of 0.457 and 0.293 of Pseudomonas and Aeromonas isolates, respectively, indicated that these isolates were exposed to high risk sources of contamination where antibiotics were commonly used. Approximately 33% of Pseudomonas spp. and 28% of Aeromonas spp. isolates from catfish contained class 1 integrons, but no class 2 integrons were detected. Several common resistance genes including aadA, dfrA and catB were harbored in class 1 integrons. Large plasmids (>55 kb) were frequently detected in 50% and 71.4% of the plasmids extracted from Pseudomonas and Aeromonas isolates, respectively. Conjugation and transformation experiments demonstrated the successful transfer of all or part of the resistance phenotypes of catfish isolates to the recipient strains, including laboratory strains and strains isolated from this study. These results highlight the likely role of catfish bacteria as a reservoir of antibiotic resistant, Gram-negative bacteria harboring a pool of mobile genetic elements that can readily be transferred intra- and interspecies. To our knowledge, this is the first report on molecular characterization of antibiotic resistance of bacteria isolated from catfish in Vietnam.

  12. Erosion Between Two Delta Fronts, the Mekong Delta Case

    NASA Astrophysics Data System (ADS)

    Unverricht, D.; Heinrich, C.; Nguyen, T. C.; Szczucinski, W.; Schwarzer, K.; Stattegger, K.

    2013-12-01

    Human activities, like embanking, sand mining, groundwater extraction and deforestation lead to strong changes of the deltaic environment. Especially, mangrove cutting influences strongly the coastal erosion along large areas of the southern Mekong delta coast. However, all currently published data document erosion from subaerial areas excluding the subaqueous Mekong delta. Our study fills this gap along the subaqueous Mekong Delta between the Bassac River mouth and the Gulf of Thailand. Hydroacoustic profiles and sediment coring were carried out during two cruises in 2007 and 2008. Analyses of ADCP measurements provide valuable information of current direction and velocity during the inter-monsoon season. Fine sediment dynamics including SPM were analyzed applying laser in situ scattering and Transmissiometry (LISST) at vertical profiles. Two delta fronts were found more than 200 km apart, one in front of the main Mekong river distributaries and the other around Ca Mau Cape, the south-western most spit of the Mekong River Delta. Although the delta front around Ca Mau Cape is not directly supplied by the main distributaries of the Mekong River, it is the fastest prograding region of the subaqueous Mekong delta. Alongshore sediment transport takes place from the north-eastern main distributaries towards south-west (Ca Mau Cape). Between both delta fronts, a large scale alternating sand-ridge-system, at least 120 km long and 6 to 10 km wide (ridge crest distance), has developed where erosional channels separate two sand-ridge bodies. The origin of the sand-ridge system is situated at the delta slope off Ganh Hao around water depths between 10 and 18 m. Here, the delta slope consists mainly of fine sand in the upper layer (up to 20 cm thickness) and is separated by an erosional hiatus from the lower muddy layer. The mangroves and sandy beaches at the coast in this region are also under erosion. It is assumed that the eroded beach sand feeds the sand-ridge-system. The

  13. Floods in the Mekong Delta: a future perspective

    NASA Astrophysics Data System (ADS)

    Dung, N. V.; Apel, H.; Thang, T. D.

    2009-04-01

    The Mekong Delta in Vietnam is one of the largest estuaries on Earth and is annually flooded to a large extend. These floods are the basis for the highly productive agricultural sector in the Delta providing both nutrients and irrigation water for the large scale paddy rice farming, but also for a productive aquaculture and environmental stability. Being an annual event people in the delta arranged their livelihoods to the repeated flood conditions. However, extreme events pose a large threat to both people and environment. Considering the extremely low topography of the Delta and the expected sea level rise caused by climate change, these events are expected to occur more frequently. In order to give a quantitative assessment of future flooding conditions, a 1D hydraulic model of the whole Mekong Delta has been developed within the WISDOM project (www.wisdom.caf.dlr.de), including the important buffer system of the Tonle Sap lake system in Cambodia. Within the model a new concept for the representation of the floodplains in a 1D model has been developed. The model was calibrated on the extraordinary flood in 2000 and validated on the flood in 2001. For an assessment of the future conditions, scenarios of sea level rise as estimated by the IPCC were used as raised downstream boundary conditions and simulations for average as well as extreme flood discharges were simulated. The obtained results show a significant increase in flooded area and depths and can be used as the basis for future flood mitigation planning.

  14. Water metagenomic analysis reveals low bacterial diversity and the presence of antimicrobial residues and resistance genes in a river containing wastewater from backyard aquacultures in the Mekong Delta, Vietnam.

    PubMed

    Nakayama, Tatsuya; Tuyet Hoa, Tran Thi; Harada, Kazuo; Warisaya, Minae; Asayama, Megumi; Hinenoya, Atsushi; Lee, Joon Won; Phu, Tran Minh; Ueda, Shuhei; Sumimura, Yoshinori; Hirata, Kazumasa; Phuong, Nguyen Thanh; Yamamoto, Yoshimasa

    2017-03-01

    The environmental pathways for the dissemination of antibiotic resistance have recently received increased attention. Aquatic environments act as reservoirs or sources of antimicrobial-resistant bacteria, antimicrobial residues, and antimicrobial resistance genes (ARGs). Therefore, it is imperative to identify the role of polluted water in the dissemination of antimicrobial resistance. The aim of this study was to evaluate the antimicrobial residues, ARGs, and microbiota in the freshwater systems of the Mekong Delta. We selected 12 freshwater sites from aquacultures and rivers in Can Tho, Vietnam and analyzed them for 45 antimicrobial residues and 8 ARGs by LC/MS/MS and real-time PCR, respectively. A 16S rDNA-based metagenomic analysis was conducted to characterize the water microbiota. Residues of sulfamethoxazole (10/12) and sulfadimidine (7/12) were widely detected, together with the sulfa-resistance genes sul1 (11/12) and sul2 (9/12). Additionally, sulfamethoxazole residues and the β-lactamase-resistance gene blaCTX-M-1 were detected in eight freshwater systems (8/12), suggesting that these freshwater systems may have been polluted by human activity. The metagenomic analysis showed that all the tested freshwater systems contained the phyla Proteobacteria, Actinobacteria, and Bacteroidetes, representing 64% of the total microbiota. Moreover, the Cai Rang River site (Ri-E), which is located at the merge point of wastewaters from backyard-based aquacultures, contained the genera Polynucleobacter, Variovorax, and Limnohabitans, representing more than 78.4% of the total microbiota. Bacterial diversity analysis showed that the Ri-E exhibited the lowest diversity compared with other regions. Principal coordinate analysis showed that the differences among water microbiotas in backyard-based aquacultures could be explained by the farmers' aquaculture techniques. In conclusion, this study demonstrated a collapse of bacterial diversity at the merge point of wastewaters

  15. Recent morphological changes in the Mekong and Bassac river channels, Mekong delta: The marked impact of river-bed mining and implications for delta destabilisation

    NASA Astrophysics Data System (ADS)

    Brunier, Guillaume; Anthony, Edward J.; Goichot, Marc; Provansal, Mireille; Dussouillez, Philippe

    2014-11-01

    The Mekong delta, in Vietnam, is the world's third largest delta. Densely populated, the delta has been significantly armoured with engineering works and dykes to protect populations and infrastructure from storms, and shrimp farms from saltwater intrusion. Considerable development pressures in Vietnam and in the upstream countries have resulted in the construction of several dams in China and in important channel-bed aggregate extractions especially in Cambodia. The effects of these developments impact the delta dynamics in various ways. In this study, changes in the channel morphology of the Mekong proper and the Bassac, the two main distributaries in the 250 km-long deltaic reach from the Cambodian border to the coast, were analysed using channel depth data for 1998 and 2008. The channels display important and irregular bed changes over the 10-year comparison period, including significant incision and expansion and deepening of numerous pools. The mean depth of both channels increased by more than 1.3 m. Both channels also showed correlative significant bed material losses: respectively 90 million m3 in the Mekong and 110 million m3 in the Bassac over the 10-year period. These important losses over a relatively short period, and weak correlations between bed incision and hydraulic parameters suggest that the marked morphological changes are not in equilibrium with flow and sediment entrainment conditions, and are therefore not related to changes in river hydrology. We claim that aggregate extraction, currently practised on a very large scale in the Mekong delta channels and upstream of the delta, is the main cause of these recent morphological changes. These changes are deemed to contribute actively to rampant bank erosion in the delta as well as to erosion of the Mekong delta shoreline. Other contributory activities include the numerous dykes and embankments. The role of existing dams in bed losses remains unclear in the absence of reliable data on the Mekong

  16. Arsenic exposure to drinking water in the Mekong Delta.

    PubMed

    Merola, R B; Hien, T T; Quyen, D T T; Vengosh, A

    2015-04-01

    Arsenic (As) contamination of groundwater drinking sources was investigated in the Mekong Delta, Vietnam in order to assess the occurrence of As in the groundwater, and the magnitude of As exposure of local residents through measurements of As in toenails of residents consuming groundwater as their major drinking water source. Groundwater (n=68) and toenail (n=62) samples were collected in Dong Thap Province, adjacent to the Mekong River, in southern Vietnam. Fifty-three percent (n=36) of the wells tested had As content above the World Health Organization's (WHO) recommended limit of 10 ppb. Samples were divided into Northern (mean As=4.0 ppb) and Southern (329.0 ppb) groups; wells from the Southern group were located closer to the Mekong River. Elevated As contents were associated with depth (<200 m), salinity (low salinity), and redox state (reducing conditions) of the study groundwater. In 79% of the wells, As was primarily composed of the reduced As(III) species. Arsenic content in nails collected from local residents was significantly correlated to As in drinking water (r=0.49, p<0.001), and the relationship improved for pairs in which As in drinking water was higher than 1 ppb (r=0.56, p<0.001). Survey data show that the ratio of As in nail to As in water varied among residents, reflecting differential As bioaccumulation in specific exposed sub-populations. The data show that water filtration and diet, particularly increased consumption of animal protein and dairy, and reduced consumption of seafood, were associated with lower ratios of As in nail to As in water and thus could play important roles in mitigating As exposure in areas where As-rich groundwater is the primary drinking water source.

  17. Dimensions of gender relations and reproductive health inequity perceived by female undergraduate students in the Mekong Delta of Vietnam: a qualitative exploration

    PubMed Central

    2012-01-01

    Introduction Increasing evidence indicates that gender equity has a significant influence on women’s health; yet few culturally specific indicators of gender relations exist which are applicable to health. This study explores dimensions of gender relations perceived by female undergraduate students in southern Vietnamese culture, and qualitatively examines how this perceived gender inequity may influence females’ sexual or reproductive health. Methods Sixty-two female undergraduate students from two universities participated in eight focus group discussions to talk about their perspectives regarding national and local gender equity issues. Results Although overall gender gaps in the Mekong Delta were perceived to have decreased in comparison to previous times, several specific dimensions of gender relations were emergent in students’ discussions. Perceived dimensions of gender relations were comparable to theoretical structures of the Theory of Gender and Power, and to findings from several reports describing the actual inferiority of women. Allocation of housework and social paid work represented salient dimensions of labor. The most salient dimension of power related to women in positions of authority. Salient dimensions of cathexis related to son preference, women’s vulnerability to blame or criticism, and double standards or expectations. Findings also suggested that gender inequity potentially influenced women’s sexual and reproductive health as regards to health information seeking, gynecological care access, contraceptive use responsibility, and child bearing. Conclusion Further investigations of the associations between gender relations and different women’s sexual and reproductive health outcomes in this region are needed. It may be important to address gender relations as a distal determinant in health interventions in order to promote gender-based equity in sexual and reproductive health. PMID:23095733

  18. The Brown Water Navy in the Mekong Delta: COIN in the Littorals and Inland Waters

    DTIC Science & Technology

    2008-01-01

    Apocalypse Insurgency & Terrorism, 2nd ed. (Washington, DC: Potomac Books, Inc, 2005) 164-187 4 Mark Moyar, Phoenix and the Birds of Prey...Mark. Phoenix and the Birds of Prey, Lincoln, NE: University of(:J Nebraska Press. 1997. 27 The Brown Water Navy in the Mekong Delta: COIN in the...Advisors in Vietnam, Annapolis, MD: Naval Institute Press, 2000. \\ Moyar , Mark. Phoenix and the Birds of Prey, Lincoln, NE: University of Nebraska

  19. Constant sediment budget of Mekong delta shorelines: implications from long-term shoreline changes

    NASA Astrophysics Data System (ADS)

    Tamura, T.; Saito, Y.; Nguyen, V. L.; Ta, T. K. O.

    2015-12-01

    The sustainability of delta shorelines requires the sufficient sediment supply that is equal to or more than the sediment removal by tides and waves. The Mekong River delta, southern Vietnam, is a mixed-energy, complicated system with multiple delta plain shorelines that share the sediment supply from the river. We reconstructed the long-term shoreline changes of the Mekong delta over the last 2500 years based on the architecture and chronology of beach ridges on three delta plain in Ben Tre (North, Central, and South Ben Tre), and a delta plain in Tra Vinh to consider the sediment flux and its contribution to the growth of individual delta plains. While each delta plain shows temporal changes in growth rate, the sum of these four plains is nearly constant. This implies that the net sediment supply to the shorelines is constant, and that the geomorphological changes at distributary branches cause changes in sediment supply to each shoreline compartment. The distributary between North and Central Ben Tre was choked sometime between 500 and 1000 years ago, causing the rapid and stagnant shoreline progradation in North and Central Ben Tre, respectively. The shoreline of Central Ben Tre however has prograded slowly even after the choking, suggesting the beach sand can be supplied beyond the distributary or onshore from the delta front. Pre-industrial changes in delta geomorphology, based on geological records, improve the understanding of the delta systems and when compared with historical changes, diagnose the post-industrial state of delta.

  20. Learning Environment in Vietnamese Physics Teacher Education Programme through the Lens of Constructivism: A Case Study of a State University in Mekong Delta Region, Vietnam

    ERIC Educational Resources Information Center

    Thao-Do, Thi Phuong; Bac-Ly, Dang Thi; Yuenyong, Chokchai

    2016-01-01

    Constructivism was introduced to Vietnam through many ways such as workshops, books, the Internet, and so on. However, due to the lack of professional education, fundamental ideas of constructivist learning perhaps were missing or neglected through classroom activities. Furthermore, due to the influence of culture and society, Vietnamese…

  1. Effects of Sequential Applications of Bassa 50EC (Fenobucarb) and Vitashield 40EC (Chlorpyrifos ethyl) on Acetylcholinesterase Activity in Climbing Perch (Anabas testudineus) Cultured in Rice Fields in the Mekong Delta, Vietnam.

    PubMed

    Tam, Nguyen Thanh; Berg, Håkan; Laureus, Jenny; Cong, Nguyen Van; Tedengren, Michael

    2016-07-01

    This study assesses the effects of sequential applications of the insecticides Bassa 50EC (fenobucarb-F) and Vitashield 40EC (chlorpyrifos ethyl-CPF), sprayed at concentrations used by rice farmers in the Mekong Delta, on the brain acetylcholinesterase (AChE) in climbing perch fingerlings. After spraying the pesticides on the rice fields, the water concentrations of both insecticides decreased below the detection levels within 3 days. The sequential applications caused significant inhibition on the brain AChE activity in the exposed fish. The inhibition by F was quicker, but less prolonged, than for CPF. The inhibition levels caused by the sequential applications were lower than those caused by only CPF and by a mixture of CPF and F. The results indicate that sequential applications of pesticides could have a negative impact on aquatic organisms and fish yields, with implication for the aquatic biodiversity, local people's livelihood and the aquaculture industry in the Mekong Delta.

  2. Correlation Between HIV and Sexual Behavior, Drug Use, Trichomoniasis and Candidiasis Among Female Sex Workers in a Mekong Delta Province of Vietnam

    PubMed Central

    Nguyen, Thuong Vu; Khuu, Nghia Van; Truong, Phong Hoai; Nguyen, Anh Phuong; Truong, Lien Xuan Thi

    2010-01-01

    To determine the prevalence of HIV and correlates of HIV infection among female sex workers (FSWs) in Soc Trang province, Vietnam, a survey of 406 FSWs in Soc Trang province was conducted between May and August, 2003. The participants were interviewed, using a standardized interview, to obtain information about sociodemographic and behavioral characteristics, and gynecologic and sexually transmitted infection (STI) history. The prevalence of HIV was 3.3%. An increased risk for HIV was associated with ever using illicit drugs, direct sex work, early sexual debut, age of FSWs, and infection with candidiasis and trichomoniasis. Reduced likelihood of HIV was only associated with withdrawal as a contraceptive method. A strong association of HIV with drug use and candidiasis and trichomoniasis infection among FSWs was found. Needle/syringe exchange, STI treatment, and methadone programs targeting FSWs should be implemented, and should include 100% condom use promotion. PMID:19085101

  3. Correlation between HIV and sexual behavior, drug use, trichomoniasis and candidiasis among female sex workers in a Mekong Delta province of Vietnam.

    PubMed

    Nguyen, Thuong Vu; Khuu, Nghia Van; Truong, Phong Hoai; Nguyen, Anh Phuong; Truong, Lien Xuan Thi; Detels, Roger

    2009-10-01

    To determine the prevalence of HIV and correlates of HIV infection among female sex workers (FSWs) in Soc Trang province, Vietnam, a survey of 406 FSWs in Soc Trang province was conducted between May and August, 2003. The participants were interviewed, using a standardized interview, to obtain information about socio-demographic and behavioral characteristics, and gynecologic and sexually transmitted infection (STI) history. The prevalence of HIV was 3.3%. An increased risk for HIV was associated with ever using illicit drugs, direct sex work, early sexual debut, age of FSWs, and infection with candidiasis and trichomoniasis. Reduced likelihood of HIV was only associated with withdrawal as a contraceptive method. A strong association of HIV with drug use and candidiasis and trichomoniasis infection among FSWs was found. Needle/syringe exchange, STI treatment, and methadone programs targeting FSWs should be implemented, and should include 100% condom use promotion.

  4. Association between climate factors and diarrhoea in a Mekong Delta area.

    PubMed

    Phung, Dung; Huang, Cunrui; Rutherford, Shannon; Chu, Cordia; Wang, Xiaoming; Nguyen, Minh; Nguyen, Nga Huy; Manh, Cuong Do; Nguyen, Trung Hieu

    2015-09-01

    The Mekong Delta is vulnerable to changes in climate and hydrological events which alter environmental conditions, resulting in increased risk of waterborne diseases. Research exploring the association between climate factors and diarrhoea, the most frequent waterborne disease in Mekong Delta region, is sparse. This study evaluated the climate-diarrhoea association in Can Tho city, a typical Mekong Delta area in Vietnam. Climate data (temperature, relative humidity, and rainfall) were obtained from the Southern Regional Hydro-Meteorological Centre, and weekly counts of diarrhoea visits were obtained from Can Tho Preventive Medicine Centre from 2004 to 2011. Analysis of climate and health variables was carried out using spline function to adjust for seasonal and long-term trends of variables. A distributed lag model was used to investigate possible delayed effects of climate variables on diarrhoea (considering 0-4 week lag periods), then the multivariate Poisson regression was used to examine any potential association between climate factors and diarrhoea. The results indicated that the diarrhoea incidence peaked within the period August-October annually. Significant positive associations were found between increased diarrhoea and high temperature at 4 weeks prior to the date of hospital visits (IRR = 1.07; 95 % CI = 1.04-1.08), high relative humidity (IRR = 1.13; 95 % CI = 1.12-1.15) and high (>90th percentile) cumulative rainfall (IRR = 1.05; 95 % CI = 1.05-1.08). The association between climate factors and diarrhoea was stronger in rural than urban areas. These findings in the context of the projected changes of climate conditions suggest that climate change will have important implications for residential health in Mekong Delta region.

  5. Association between climate factors and diarrhoea in a Mekong Delta area

    NASA Astrophysics Data System (ADS)

    Phung, Dung; Huang, Cunrui; Rutherford, Shannon; Chu, Cordia; Wang, Xiaoming; Nguyen, Minh; Nguyen, Nga Huy; Manh, Cuong Do; Nguyen, Trung Hieu

    2015-09-01

    The Mekong Delta is vulnerable to changes in climate and hydrological events which alter environmental conditions, resulting in increased risk of waterborne diseases. Research exploring the association between climate factors and diarrhoea, the most frequent waterborne disease in Mekong Delta region, is sparse. This study evaluated the climate-diarrhoea association in Can Tho city, a typical Mekong Delta area in Vietnam. Climate data (temperature, relative humidity, and rainfall) were obtained from the Southern Regional Hydro-Meteorological Centre, and weekly counts of diarrhoea visits were obtained from Can Tho Preventive Medicine Centre from 2004 to 2011. Analysis of climate and health variables was carried out using spline function to adjust for seasonal and long-term trends of variables. A distributed lag model was used to investigate possible delayed effects of climate variables on diarrhoea (considering 0-4 week lag periods), then the multivariate Poisson regression was used to examine any potential association between climate factors and diarrhoea. The results indicated that the diarrhoea incidence peaked within the period August-October annually. Significant positive associations were found between increased diarrhoea and high temperature at 4 weeks prior to the date of hospital visits (IRR = 1.07; 95 % CI = 1.04-1.08), high relative humidity (IRR = 1.13; 95 % CI = 1.12-1.15) and high (>90th percentile) cumulative rainfall (IRR = 1.05; 95 % CI = 1.05-1.08). The association between climate factors and diarrhoea was stronger in rural than urban areas. These findings in the context of the projected changes of climate conditions suggest that climate change will have important implications for residential health in Mekong Delta region.

  6. Prevalence and risk factors for carriage of antimicrobial-resistant Escherichia coli on household and small-scale chicken farms in the Mekong Delta of Vietnam

    PubMed Central

    Nguyen, Vinh Trung; Carrique-Mas, Juan J.; Ngo, Thi Hoa; Ho, Huynh Mai; Ha, Thanh Tuyen; Campbell, James I.; Nguyen, Thi Nhung; Hoang, Ngoc Nhung; Pham, Van Minh; Wagenaar, Jaap A.; Hardon, Anita; Thai, Quoc Hieu; Schultsz, Constance

    2015-01-01

    Objectives To describe the prevalence of antimicrobial resistance among commensal Escherichia coli isolates on household and small-scale chicken farms, common in southern Vietnam, and to investigate the association of antimicrobial resistance with farming practices and antimicrobial usage. Methods We collected data on farming and antimicrobial usage from 208 chicken farms. E. coli was isolated from boot swab samples using MacConkey agar (MA) and MA with ceftazidime, nalidixic acid or gentamicin. Isolates were tested for their susceptibility to 11 antimicrobials and for ESBL production. Risk factor analyses were carried out, using logistic regression, at both the bacterial population and farm levels. Results E. coli resistant to gentamicin, ciprofloxacin and third-generation cephalosporins was detected on 201 (96.6%), 191 (91.8%) and 77 (37.0%) of the farms, respectively. Of the 895 E. coli isolates, resistance to gentamicin, ciprofloxacin and third-generation cephalosporins was detected in 178 (19.9%), 291 (32.5%) and 29 (3.2%) of the isolates, respectively. Ciprofloxacin resistance was significantly associated with quinolone usage (OR = 2.26) and tetracycline usage (OR = 1.70). ESBL-producing E. coli were associated with farms containing fish ponds (OR = 4.82). Conclusions Household and small farms showed frequent antimicrobial usage associated with a high prevalence of resistance to the most commonly used antimicrobials. Given the weak biocontainment, the high prevalence of resistant E. coli could represent a risk to the environment and to humans. PMID:25755000

  7. Vulnerability of climate change and its adaptation in the Mekong Delta: monitoring and resident's perception along the coast

    NASA Astrophysics Data System (ADS)

    Tamura, M.; Yasuhara, K.

    2014-12-01

    The Mekong Delta in Vietnam is expected to face challenges from various forms of climate-induced events. In addition, a growing population, which currently stands at 18.6 million people lives in the Mekong Delta, Vietnam. Therefore, the Mekong Delta is the focus of international action for adaptation. However, many climate sensitive regions and communities are unprepared for climate-induced natural disasters due to mismatch in perception with their respective risks. This study examines the vulnerability and appropriate adaptation in the Mekong Delta from both scientific and regional aspects. First, we show the change in coastal areas in Soc Trang province, comparing the past to the present images using Unmanned Aerial Vehicle (UAV) and satellite. We identify some vulnerable areas which derived from multiple factors due to coastal erosion, flooding, and sea level rise. Second, we present results of perception survey about climate change and the adaptation at community level in Ca Mau, Soc Trang, and An Giang Provinces, which were conducted in 2012 and 2014. While the findings suggest varying degrees of adaptation to seasonal flooding by raising the ground floors of their homes and repairing houses, their capacity to prepare for extreme flooding is limited in spite of the residents' awareness of the increasing frequency and intensity of natural disasters. Third, we propose an erosion-resistant dyke reinforcement technique by mixing natural palm tree fiber and cement, both of which are locally available materials in the Mekong Delta. It is expected that adaptation with multiple protections in accordance to regional feature can work well for such coastal disasters.

  8. Monitoring rice farming activities in the Mekong Delta region

    NASA Astrophysics Data System (ADS)

    Nguyen, S. T.; Chen, C. F.; Chen, C. R.; Chiang, S. H.; Chang, L. Y.; Khin, L. V.

    2015-12-01

    Half of the world's population depends on rice for survival. Rice agriculture thus plays an important role in the developing world's economy. Vietnam is one of the largest rice producers and suppliers on earth and more than 80% of the exported rice was produced from the Mekong Delta region, which is situated in the southwestern Vietnam and encompasses approximately 40,000 km2. Changes in climate conditions could likely trigger the increase of insect populations and rice diseases, causing the potential loss of rice yields. Monitoring rice-farming activities through crop phenology detection can provide policymakers with timely strategies to mitigate possible impacts on the potential yield as well as rice grain exports to ensure food security for the region. The main objective of this study is to develop a logistic-based algorithm to investigate rice sowing and harvesting activities from the multi-temporal Moderate Resolution Imaging Spectroradiometer (MODIS)-Landsat fusion data. We processed the data for two main cropping seasons (i.e., winter-spring and summer-autumn seasons) through a three-step procedure: (1) MODIS-Landsat data fusion, (2) construction of the time-series enhanced vegetation index 2 (EVI2) data, (3) rice crop phenology detection. The EVI2 data derived from the fusion results between MODIS and Landsat data were compared with that of Landsat data indicated close correlation between the two datasets (R2 = 0.93). The time-series EVI2 data were processed using the double logistic method to detect the progress of sowing and harvesting activities in the region. The comparisons between the estimated sowing and harvesting dates and the field survey data revealed the root mean squared error (RMSE) values of 8.4 and 5.5 days for the winter-spring crop and 9.4 and 12.8 days for the summer-autumn crop, respectively. This study demonstrates the effectiveness of the double logistic-based algorithm for rice crop monitoring from temporal MODIS-Landsat fusion data

  9. Crop Uptake of Arsenic from Flooded Paddy Fields in the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Mohr, K.; Boye, K.

    2014-12-01

    Arsenic is found naturally in the soils in the Mekong delta in Vietnam and Cambodia. It originates from erosion in the Himalayas. When similar levels of arsenic are present in well aerated soil, it is not dangerous, because it is strongly bound to soil particles and not readily plant available. Arsenic is released when the soil is saturated with water, and therefore contaminates crops grown in flooded fields. This results in people being exposed to unsafe levels of arsenic from their food, such as rice and lotus, which are normally grown under flooded conditions. Rice is a staple food in these regions, so the transfer of arsenic from soil, to water, and ultimately into the grain, poses a threat to human health. We have conducted a limited, preliminary field survey of arsenic levels in soil, flood water, and crops from distinctly different paddy fields in the lower Mekong delta in Vietnam and Cambodia. The purpose of the study was to identify soils and crops (or specific plant parts) that are especially prone to arsenic transfer from soil to crop, and vice versa (i.e. arsenic uptake is prevented in spite of being present in the soil). In addition to arsenic concentration in soil, plant and water, we are examining other elements, such as carbon, nitrogen, sulfur and iron, which give us clues about what chemical and microbial processes that control the overall arsenic uptake.

  10. Responding to rising sea levels in the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Smajgl, A.; Toan, T. Q.; Nhan, D. K.; Ward, J.; Trung, N. H.; Tri, L. Q.; Tri, V. P. D.; Vu, P. T.

    2015-02-01

    Vietnamese communities in the Mekong Delta are faced with the substantial impacts of rising sea levels and salinity intrusion. The construction of embankments and dykes has historically been the principal strategy of the Vietnamese government to mitigate the effects of salinity intrusion on agricultural production. A predicted sea-level rise of 30 cm by the year 2050 is expected to accelerate salinity intrusion. This study combines hydrologic, agronomic and behavioural assessments to identify effective adaptation strategies reliant on land-use change (soft options) and investments in water infrastructure (hard options). As these strategies are managed within different policy portfolios, the political discussion has polarized between choices of either soft or hard options. This paper argues that an ensemble of hard and soft policies is likely to provide the most effective results for people's livelihoods in the Mekong Delta. The consequences of policy deliberations are likely to be felt beyond the Mekong Delta as levels of rice cultivation there also affect national and global food security.

  11. Recent morphodynamic evolution of coastline of Mekong river Delta, towards an increased vulnerability

    NASA Astrophysics Data System (ADS)

    Besset, Manon; Brunier, Guillaume; Anthony, Edward

    2015-04-01

    river delta and generate considerable risks to residents. Thus, nearly 12,000 people were evacuated from the Giang region in 2014 (Vietnam News, 2014) as a result of coastal erosion. This growing vulnerability related to erosion is combined with the problems of subsidence and susceptibility to flooding which are already rendering the Mekong river delta one of the most vulnerable and threatened deltas (Syvitski et al., 2009).

  12. Large-scale suspended sediment transport and sediment deposition in the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Manh, N. V.; Dung, N. V.; Hung, N. N.; Merz, B.; Apel, H.

    2014-08-01

    Sediment dynamics play a major role in the agricultural and fishery productivity of the Mekong Delta. However, the understanding of sediment dynamics in the delta, one of the most complex river deltas in the world, is very limited. This is a consequence of its large extent, the intricate system of rivers, channels and floodplains, and the scarcity of observations. This study quantifies, for the first time, the suspended sediment transport and sediment deposition in the whole Mekong Delta. To this end, a quasi-2D hydrodynamic model is combined with a cohesive sediment transport model. The combined model is calibrated using six objective functions to represent the different aspects of the hydraulic and sediment transport components. The model is calibrated for the extreme flood season in 2011 and shows good performance for 2 validation years with very different flood characteristics. It is shown how sediment transport and sediment deposition is differentiated from Kratie at the entrance of the delta on its way to the coast. The main factors influencing the spatial sediment dynamics are the river and channel system, dike rings, sluice gate operations, the magnitude of the floods, and tidal influences. The superposition of these factors leads to high spatial variability of sediment transport, in particular in the Vietnamese floodplains. Depending on the flood magnitude, annual sediment loads reaching the coast vary from 48 to 60% of the sediment load at Kratie. Deposited sediment varies from 19 to 23% of the annual load at Kratie in Cambodian floodplains, and from 1 to 6% in the compartmented and diked floodplains in Vietnam. Annual deposited nutrients (N, P, K), which are associated with the sediment deposition, provide on average more than 50% of mineral fertilizers typically applied for rice crops in non-flooded ring dike floodplains in Vietnam. Through the quantification of sediment and related nutrient input, the presented study provides a quantitative basis for

  13. Changes in Ecosystem Services and related Livelihoods in the Mekong Delta: vulnerabilities and adaptation strategies

    NASA Astrophysics Data System (ADS)

    Sebesvari, Z.; Renaud, F. G.

    2014-12-01

    The Mekong Delta (Vietnam) is highly vulnerable to the many impacts of global environmental change as well as to the accelerating anthropogenic changes in the catchment and in the delta itself. Today the delta is an agricultural landscape controlled by engineering structures such as channels, dykes, embankments, and sluice gates. These structures have been constructed gradually over the last 200 years mainly for irrigation and flood control in the upper part of the delta and to control saline intrusion in the coastal areas. Recent changes in the hydrology mainly driven by upstream hydropower development on the mainstream and the tributaries of the Mekong will likely have far reaching impacts on the delta´s social-ecological systems through changes in e.g. sedimentation processes, nutrient transport as well as the health of aquatic ecosystems. Further threats to the delta include sea level rise and an increase in seasonal rainfall variability leading to an increase in flood variability. These changes affect the lives of millions of low-income inhabitants who depend on the ecosystem services provided by the Mekong for their livelihoods and sustenance. Since the changes in ecosystem service provision are occurring relatively fast while the resource dependency of the delta population is very high, adaptation becomes a challenge. An assessment of livelihood dependencies on ecosystem services requires an understanding of ecosystem services affected by different drivers of change, as well as of the types of livelihoods likely to be jeopardized as a result of these changes. We will present main ecosystem services supporting specific livelihoods, discuss how they are threatened, and analyse the merits of potential solutions. Options based solely on grey infrastructure might be problematic on the long term while an integration of ecosystem based solution such as a (re)adaptation of agricultural production systems to floods in the upper delta might be a more sustainable

  14. Extreme floods in the Mekong River Delta under climate change: combined impacts of upstream hydrological changes and sea level rise

    NASA Astrophysics Data System (ADS)

    Hoang, Long; Nguyen Viet, Dung; Kummu, Matti; Lauri, Hannu; Koponen, Jorma; van Vliet, Michelle T. H.; Supit, Iwan; Leemans, Rik; Kabat, Pavel; Ludwig, Fulco

    2016-04-01

    Extreme floods cause huge damages to human lives and infrastructure, and hamper socio-economic development in the Mekong River Delta in Vietnam. Induced by climate change, upstream hydrological changes and sea level rise are expected to further exacerbate future flood hazard and thereby posing critical challenges for securing safety and sustainability. This paper provides a probabilistic quantification of future flood hazard for the Mekong Delta, focusing on extreme events under climate change. We developed a model chain to simulate separate and combined impacts of two drivers, namely upstream hydrological changes and sea level rise on flood magnitude and frequency. Simulation results show that upstream changes and sea level rise substantially increase flood hazard throughout the whole Mekong Delta. Due to differences in their nature, two drivers show different features in their impacts on floods. Impacts of upstream changes are more dominant in floodplains in the upper delta, causing an increase of up to +0.80 m in flood depth. Sea level rise introduces flood hazard to currently safe areas in the middle and coastal delta zones. A 0.6 m rise in relative sea level causes an increase in flood depth between 0.10 and 0.70 m, depending on location by 2050s. Upstream hydrological changes and sea level rise tend to intensify each other's impacts on floods, resulting in stronger combined impacts than linearly summed impacts of each individual driver. Substantial increase of future flood hazard strongly requires better flood protection and more flood resilient development for the Mekong Delta. Findings from this study can be used as quantified physical boundary conditions to develop flood management strategies and strategic delta management plans.

  15. Erosion of the Mekong delta: the role of human activities

    NASA Astrophysics Data System (ADS)

    Anthony, E.; Dussouillez, P.; Goichot, M.; Brunier, G.; Dolique, F.; Nguyen, V.; Loisel, H.; Mangin, A.; Vantrepotte, V.

    2013-12-01

    River deltas are threatened by dams, dykes, flow channelling, and aggregate extraction. These activities outweigh climate change and sea-level rise in causing delta vulnerability1, and will aggravate the impacts to be expected from these effects2. We show here from analysis of: (1) delta channel morphology and sediment budgets, and (2) satellite imagery, that the Mekong delta, considered as the world's third largest, and hitherto strongly prograding, is now in a phase of large-scale erosion. We discuss the mechanistic links involved in erosion and the way these are related to human activities. High-resolution (2.5 m) SPOT 5 images for the years 2003, 2007, 2011/12 covering 405 km of the delta shoreline show an overall retreat rate of over 8 m a year. 75% of the analysed shoreline, i.e., the muddy western sector, is now retreating at rates exceeding 50 m a year in places. The sandy river-mouth sector maintains a semblance of stability, but with strong variations. We attribute erosion to a cascade of morphosedimentary changes linked to sediment mining from the deltaic channels and upstream dam interception. We estimated from Meris satellite imagery an annual 5% decrease in surface suspended concentrations exiting at the mouths of the Mekong over the period 2003-2011 that may reflect increased trapping of mud behind dams in China. We also infer modification of river-mouth and coastal mud storage patterns resulting from a loss of ca. 200 million m3 of delta channel sediments between 1998 and 2008 from aggregate extraction. Dykes have been shown to result in increased channel flow velocities during the high-discharge monsoon season, favouring further channel deepening3. Stronger river-mouth outflow velocities during this season may be leading to export of a greater proportion of mud far offshore of the coastal longshore transport corridor that ensured mud supply to, and past progradation of, the muddy western coast. In contrast, greater seawater penetration in the

  16. Future flood hazard under climate change in the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Apel, H.; Dung, N. V.; Delgado, J. M.; Merz, B.

    2012-04-01

    The main characteristic of flood hazard estimations is the association of a probability of occurrence to a flood event of a defined magnitude. This is usually performed via frequency analysis assuming stationarity and independence of the analyzed time series. This assumption, however, often does not hold true even for historical records and periods and it will be even more challenged under the expected impact of climate change to the water cycle in general and flood probabilities and magnitudes in particular. Thus strategies and methods have to be developed and evaluated for accounting for climate change impacts on flood hazard. In the presented contribution two options are presented and compared for the Mekong Delta, one of the most endangered areas with respect to climate change world-wide. The first method takes non-stationarity explicitly into account by analyzing the observed time series of peak discharge and flood volume at the upper boundary of the Delta with non-stationary extreme value statistics. The two variables and their dependence are modeled by a copula, coupling their marginal distributions to a joint bivariate distribution. Using this copula in combination with characteristic normalized flood hydrographs, probabilistic flood hazard maps for the Mekong Delta are generated via a large scale hydrodynamic model of the Delta embedded in a Monte Carlo framework for the reference year 2009. In order to account for climate change the observed trend in the non-stationary extreme value distribution was simply extrapolated to two future time horizons 2030 and 2050. However, the extrapolations of the trends are certainly associated with high level of uncertainty, in particular for time horizons in the far future. Thus we compare the simple extrapolation approach with an approach deriving future flood hazard in the Mekong Delta by establishing direct correlations between monsoon indexes describing the intensity of the flood triggering monsoon activities and the

  17. Structure of the Mekong trough

    SciTech Connect

    Van Khy, L.

    1986-01-01

    The Mekong trough occupies the shelf of southern Vietnam between the sea coast and the Condao-Cu Lao Tu line of islands and the adjacent area of the onshore Mekong delta. It extends for 400 km from southwest to northeast with a width of 100 km. The Mekong trough is situated on the upper Mesozoic volcanic belt of South Vietnam, which is part of the East Asian volcanogenic belt. It is bounded on the southeast by the Con Son high, on the southwest by the Corat-Ca Mau high, and on the northwest by the Dalat massif. The Mekong trough is considered to have major potential as a new petroleum province. Since 1969, numerous common depth point (CDP) seismic profiles have been run and seven deep wells have been drilled on the shelf in the Mekong trough. This paper is devoted to an analysis of the findings. 9 references, 4 figures.

  18. Detection of Area Changes in River Mouthbars at the Mekong River Delta using ALOS/PALSAR data

    NASA Astrophysics Data System (ADS)

    Tanaka, A.; Uehara, K.; Tamura, T.; Saito, Y.

    2011-12-01

    Projected sea-level rise by the year 2100 would be ~1m recently and its negative impact on the coastal zone has been pointed out, particularly for mega-deltas in Asia by the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC, 2007). The relative sea-level rise varies with specific conditions and processes over broad spatial and temporal scales. Therefore, long-term monitoring of geomorphological changes in coastal areas over wide areas is of highly interest and importance for coastal management. However, due to limited data availability and accessibility in developing countries, there is not enough systematic coastal monitoring. The Mekong River Delta is one of typical mega-deltas in Asia, which has a low-lying wide delta-plain located in Cambodia to South Vietnam. Sediment and water discharges of the Mekong River are controlled by the monsoon with high and low discharge in summer (wet season) and winter (dry season), respectively. Therefore, technologies such as SAR (Synthetic Aperture Radar) not affected by the cloud conditions offer potential for monitoring in the monsoon Asia region. In this study, ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band SAR) data acquired over a period from December 2006 to January 2011 are analyzed to investigate the relation between the sea level and the shape of mouthbars in the Mekong River. Level-1.0 PALSAR data were processed, coregistered, and geocoded to make SAR backscatter intensity images. River mouthbars with strong backscatter, which is surrounded by the water with weak backscatter, are successfully extracted using a histogram thresholding algorithm. Estimated areas of river mouthbars, which are located at the central part of the delta and openly faced to the South China Sea, gradually increase on an annual time scale. These river mouthbars are growing to the seaward. Besides this overall increasing trend, seasonal variations of areas are observed; these correlate with

  19. Monitoring and modeling the fate of commonly used pesticides in surface water of the Lower Mekong Delta

    NASA Astrophysics Data System (ADS)

    van Toan, Pham; Sebesvari, Zita; Loan, Vo Phuong Hong; Renaud, Fabrice

    2010-05-01

    , Vietnam. Marine Pollution Bulletin 56, 1476-1485. Dasgupta S., Meisner C., Wheeler D., Nhan L. T., Khuc X., 2005. Pesticide poisoning of farm workers: implications of blood test results from Vietnam. World Bank Policy Research Working Paper 3624. Dung, N.H., Dung, T.T., 2003. Economic and health consequences of pesticide use in paddy production in the Mekong Delta, Vietnam. Economy and environment case studies in Vietnam. Economy and environment program for Southeast Asia. Margni, M., Rossier, D., Crettaz, P., Jolliet, O., 2002. Life cycle impact assessment of pesticides on human health and ecosystems. Agriculture, Ecosystems and Environment 93, 379-392. Mekong River Committee Secretariat (MRCS), 2007. Environmental health concerns related to agro-chemical use in the Mekong Delta. Environment training case studies. Minh, N. H., Minh, T. B., Kajiwara, N., Kunisue, T., Iwata, H., Viet P.H., Tu, N. P. C., Tuyen, B. C., Tanabe, S., 2007. Pollution sources and occurrences of selected persistent organic pollutants (POPs) in sediments of the Mekong River delta, South Vietnam. Chemosphere. 67, 1794-1801. Phuong, D. M., Gopalakrishnan, C., 2003. An application of the contingent valuation method to estimate the loss of value of water resources due to pesticide contamination: the case of the Mekong Delta, Vietnam',International. Journal of Water Resources Development,19, 617-633.

  20. Floods in Mekong Delta Under Sea-Level Rise Projections By IPCC AR5

    NASA Astrophysics Data System (ADS)

    Takagi, H.

    2014-12-01

    One of the mightiest rivers in the planet, the Mekong ranks 10th amongst the world's great rivers on the basis of mean annual flow at the mouth. It flows southwards over a distance of approximately 4,800 km from its source to the sea, through six different countries: China, Myanmar, Lao PDR, Thailand, Cambodia and Vietnam. This great basin has been considered to be one of the most sensitive areas in the world to climate change. The present paper investigates fluvial flood hazards in urban areas in the Mekong Delta to inundation due to seasonal flooding, a phenomenon which is likely to be exacerbated by future sea-level rise. Unlike past researches which mainly focus on flooding due to river discharge from upstream or heavy precipitation, the present paper scrutinizes the influence of ocean tides. The research reveals that ocean tides predominantly determine water elevation even in an upstream location such as Can Tho City, 80 km inland from the river mouth, and that the river flow causes tidal damping and effectively reduces the energy of the incoming tides. This tidal damping is especially pronounced during the rainy season. Analysis based on the water levels monitored by the Mekong River Commission reveals that the ground near the riverbank of Can Tho had experienced inundation for a total of 215 hours between July 2009 and June 2010 (2.5% of the time over a one year period). It is also shown that inundation reached up to a maximum height of 47 cm above the roads of Can Tho downtown in this one-year period. Assuming two scenarios of sea-level rise of 25 cm in the middle of the 21st century and 60 cm in the end of the century, all based on the Fifth Assessment Report of Intergovernmental Panel on Climate Change (IPCC AR5) projections, it was found that the duration of inundation will be prolonged from the present percentage of 2.5% to 7.5% and 24% of the year, respectively. It is important to note that while at present this flooding is seasonal and limited, in the

  1. Low Carbon Rice Farming Practices in the Mekong Delta Yield Significantly Higher Profits and Lower Greenhouse Gas Emissions

    NASA Astrophysics Data System (ADS)

    Rudek, J.; Van Sanh, N.; Tinh, T. K.; Tin, H. Q.; Thu Ha, T.; Pha, D. N.; Cui, T. Q.; Tin, N. H.; Son, N. N.; Thanh, H. H.; Kien, H. T.; Kritee, K.; Ahuja, R.

    2014-12-01

    The Vietnam Low-Carbon Rice Project (VLCRP) seeks to significantly reduce GHG emissions from rice cultivation, an activity responsible for more than 30% of Vietnam's overall GHG emissions, while improving livelihoods for the rice farmer community by decreasing costs and enhancing yield as well as providing supplemental farmer income through the sale of carbon credits. The Mekong Delta makes up 12% of Vietnam's land area, but produces more than 50% of the country's rice, including more than 90% of the rice for export. Rice cultivation is the main source of income for 80% of farmers in the Mekong Delta. VLCRP was launched in late 2012 in the Mekong Delta in two major rice production provinces, Kien Giang and An Giang. To date, VLCRP has completed 11 crop seasons (in Kien Giang and An Giang combined), training over 400 farmer households in applying VLCRP's package of practices (known as 1 Must - 6 Reductions) and building technical capacity to its key stakeholders and rice farmer community leaders. By adopting the 1 Must- 6 Reductions practices (including reduced seeding density, reduced fertilizer and pesticide application, and alternative wetting and drying water management), rice farmers reduce their input costs while maintaining or improving yields, and decreasing greenhouse gas emissions. The VLCRP package of practices also deliver other environmental and social co-benefits, such as reduced water pollution, improved habitat for fishery resources and reduced health risks for farmers through the reduction of agri-chemicals. VLCRP farmers use significantly less inputs (50% reduction in seed, 30% reduction in fertilizer, 40-50% reduction in water) while improving yields 5-10%, leading to an increase in profit from 10% to as high as 60% per hectare. Preliminary results indicate that the 1 Must- 6 Reductions practices have led to approximately 40-65% reductions in greenhouse gas emissions, equivalent to 4 tons of CO2e/ha/yr in An Giang and 35 tons of CO2e/ha/yr in Kien

  2. A source-to-sink study of the Mekong River Delta: Hydrology, delta evolution, and sediment transport modeling

    NASA Astrophysics Data System (ADS)

    Xue, Zuo

    The Mekong River is the third largest river in the Western Pacific. As the population and economy of the area booms, more and more dams are built in the Mekong basin. Concerns about negative impacts on downstream and the delta plain from upstream damming have been raised ever since the completion of the Manwan Dam, the first of the 13 major dams designed on the Upper Mekong, in 1993. The runoff of the Lower Mekong has a closer connection with the regional precipitation and El Nino Southern Oscillation during the post-dam period (1994-2005) than the pre-dam period (1950-1993). With ˜200 new dams to be added to the basin in the next couples of decades, changes are expected in both hydrological regime and delta dynamics. The Mekong River delivers ˜160 million tons of sediment per year to the South China Sea (SCS). The Mekong River Delta (MRD) has the third largest delta plain in the world. High-resolution seismic profiling and coring during 2006 and 2007 cruises reveals a low gradient, subaqueous delta system, up to 20 m thick, surrounding the modern MRD in the west of the SCS. A late Holocene sediment budget for the MRD has been determined, based on the area and thickness of deltaic sediment. Approximately 80% of Mekong delivered sediment has been trapped within the delta area, which, together with a falling sea-level, resulted in a rapidly prograding MRD over the past 3000 yr. The late Holocene evolution of the MRD has shown a morphological asymmetry indicated by a large down-drift area and a rapid progradation around Cape Camau, ˜200 km downstream from the river mouth. The coupled hydrodynamic-sediment transport modeling using the Regional Ocean Modeling System (ROMS) and Community Sediment Transport Model System (CSTMS) showed that wind is a most important factor influencing the along-shelf sediment transport. This associates MRD's asymmetric evolution with an increased wave influence during the Neoglaciation. Coastal currents formed by the geostrophically

  3. Flood precautionary behaviour of private households in Can Tho city in the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Kreibich, Heidi; Gani Adnan, Sarfaraz; Thi Chinh, Do; Bubeck, Philip

    2015-04-01

    Flood risk is high and it is projected to increase in many places due to the effects of climate change and the on-going intensification of human activities in risk-prone areas. These projections and the considerable uncertainties associated with these developments increasingly require integrated approaches in flood risk management. In addition to flood protection, private precautionary measures aim at reducing the potential negative consequences of floods. Thus, insights into flood precautionary behaviour are important. This study is grounded on the Protection Motivation Theory (PMT), which refers to the cognitive process that people undergo when evaluating their own ability to avoid a certain risk. Results of a survey among 858 flood-prone households in Can Tho city in the Mekong Delta, Vietnam are presented. It is shown that flood-coping appraisal is an important variable in terms of precautionary behaviour. Thus, risk communication should focus more on the potential of precautionary measures to effectively reduce flood damage, as well as on information about how to implement such measures in practice.

  4. From Risk Towards Resilience: Assessing Vulnerability and Adaptability to Climate Change in the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Ling, F. H.; Yasuhara, K.; Tamura, M.; Tabayashi, Y.

    2012-12-01

    While efforts to mainstream climate adaptation have only begun in recent years, many developing regions are already taking measures to proof themselves from various natural disasters, including storm surges, flooding, land subsidence, and erosion. In the Asia-Pacific region, one of the most vulnerable in the world, climate resilience is urgently needed due to sea level rise and the increasing frequency and intensity of climate events. Yet, many regions and communities are unprepared due to insufficient awareness of disaster risks. In order to utilize the science of the changing environment more effectively, there is a critical need to understand the social context and perception of those who are affected by climate change. Using the Mekong Delta region in Vietnam as an example, we discuss our current efforts to develop a vulnerability and adaptation index for building climate resilience in the Asia-Pacific Region. A survey of current adaptation efforts in this region will be shown and preliminary findings from our survey to understand the perception of disaster risk in this region will be discussed.

  5. Integrated flood risk assessment for the Mekong Delta through the combined assessment of flood hazard change and social vulnerability

    NASA Astrophysics Data System (ADS)

    Apel, Heiko; Garschagen, Matthias; Delgado, José Miguel; Viet Dung, Nguyen; Van Tuan, Vo; Thanh Binh, Nguyen; Birkmann, Joern; Merz, Bruno

    2013-04-01

    Low lying estuaries as the Mekong Delta in Vietnam are among the most vulnerable areas with respect to climate change impacts. While regular floods are not a threat but an opportunity for livelihoods and income generation, extreme flood events can pose considerable risks to the people living in Deltas. Climate change is expected to increase the frequency of extreme floods globally, which in combination with sea level rise and a likely intensification of cyclone activity creates increased and/or entirely new hazard exposure in the Deltas. Yet, in line with the risk literature and especially the recent IPCC SREX report, flooding risk needs to be understood as deriving from the interaction of physical hazards and the vulnerabilities of exposed elements. Therefore, the paper aims for an integrated risk assessment through combining the most up to date estimates of flood hazard projections under climate change conditions in the Mekong Delta with the assessment of vulnerability patterns. Projections of flood hazard are estimated based the modulation of the flood frequency distribution by atmospheric circulation patterns. Future projections of these patterns are calculated from an ensemble of climate models. A quasi two-dimensional hydrodynamical model of the Delta is then applied to estimate water levels and flood extend. This model is fed with a set of hydrographs which are based on both the derived climate model uncertainty and the bivariate nature of floods in the Mekong Delta. Flood peak is coupled with flood volume in the probabilistic framework to derive synthetic extreme future floods with associated probabilities of occurrence. This flood hazard analysis is combined with static sea level rise scenarios, which alter the lower boundary of the hydrodynamic model and give estimates of the impact on sea level rise on inundation extend and depths. The vulnerability assessment is based on a three step approach. Firstly, vulnerability profiles are developed for different

  6. Science implementation of Forecast Mekong for food and environmental security

    USGS Publications Warehouse

    Turnipseed, D. Phil

    2012-01-01

    Forecast Mekong is a significant international thrust under the Delta Research and Global Observation Network (DRAGON) of the U.S. Geological Survey (USGS) and was launched in 2009 by the U.S. Department of State and the Foreign Ministers of Cambodia, Laos, Thailand, and Vietnam under U.S. Department of State Secretary Hillary R. Clinton's Lower Mekong Initiative to enhance U.S. engagement with countries of the Lower Mekong River Basin in the areas of environment, health, education, and infrastructure. Since 2009, the USGS has worked closely with the U.S. Department of State; personnel from Cambodia, Laos, Thailand, and Vietnam; nongovernmental organizations; and academia to collect and use research and data from the Lower Mekong River Basin to provide hands-on results that will help decisionmakers in future planning and design for restoration, conservation, and management efforts in the Lower Mekong River Basin. In 2012 Forecast Mekong is highlighting the increasing cooperation between the United States and Lower Mekong River Basin countries in the areas of food and environmental security. Under the DRAGON, Forecast Mekong continues work in interactive data integration, modeling, and visualization system by initiating three-dimensional bathymetry and river flow data along with a pilot study of fish distribution, population, and migratory patterns in the Lower Mekong River Basin. When fully developed by the USGS, in partnership with local governments and universities throughout the Mekong River region, Forecast Mekong will provide valuable planning tools to visualize the consequences of climate change and river management.

  7. Is a Decline in Tropical Storms Leading to the Demise of the Mekong Delta?

    NASA Astrophysics Data System (ADS)

    Darby, S. E.; Hackney, C. R.; Leyland, J.; Kummu, M.; Lauri, H.; Parsons, D. R.; Best, J.; Nicholas, A. P.; Aalto, R. E.

    2015-12-01

    The world's largest rivers deliver ~19 billion tonnes of sediment to the coastal zone annually, with a significant fraction sequestered in the large deltas that are home to 14% of the world's population. Most (>70%) of these large deltas are under threat from a combination of rising sea levels and ground surface subsidence, while the rivers that feed them have also been subjected to damming, substantially reducing the sediment supply that is available for delta (re)construction. In this paper we use new measurements of suspended sediment load, combined with hydrological modelling, to reconstruct inter-annual variations in sediment load with and without tropical cyclones during the period 1981-2005. We examine in particular the results at Kratie in Cambodia, a gauging station that is located within 250 km of the apex of the Mekong delta. Our results indicate that fluvial sediment loads at Kratie have undergone a large and rapid decline (at a rate of ~2 Mt/yr, reducing the annual sediment load in this period by ~50%) during the study period. This is a remarkable finding, but we also show that this decline in sediment load is attributable almost entirely to a commensurate decline in the proportion of the Mekong's sediment load that is forced by tropical storms. Our results have profound implications. The Mekong's great delta, the rice basket of SE Asia, is home to 17 million people. A sustainable supply of fluvial sediment is critical in preventing the Mekong's delta being 'drowned' by rising sea levels. In recent years attention has been focused on the likely deleterious effects of hydropower dam construction in the Mekong Basin on the future sediment loads reaching the delta. However, it is evident that the delivery of sediment from the Mekong River has already undergone a substantial reduction, similar in magnitude to that associated with future dam-induced trapping, as a result of recent changes in tropical storm climatology. A continuing dearth of tropical storms

  8. High-resolution chronology of the Mekong delta coast for characterizing and predicting decadal to centennial changes

    NASA Astrophysics Data System (ADS)

    Tamura, T.; Saito, Y.; Bateman, M. D.; Nguyen, V. L.; Ta, T.; Matsumoto, D.

    2013-12-01

    Deltaic coasts have prograded over the last several millennia after the culmination of the postglacial sea-level rise to form coastal lowlands, where nowadays c. 25% of the world's population lives. Knowing past deltaic shoreline changes, especially on decadal- to centennial-scale, is essential for understanding the fate of delta in the coming decades and centuries. We tested the effectiveness of quartz optically-stimulated luminescence (OSL) dating of beach ridges to constrain shoreline changes of the Mekong River delta, southern Vietnam. Forty-seven OSL ages were analysed from the Tra Vinh delta plain, and the beach ridge sediments were found to have excellent luminescence properties resulting in low age uncertainties of c. 5 %. The OSL chronology agrees well with shoreline changes over recent decades and with radiocarbon ages of tidal flat sediment, clearly illustrating the coastal progradation over the last 3500 years. The OSL ages show no reversal and document decadal- to centennial-scale shoreline migration especially in the last 1500 years. The chronology also suggests major changes in shoreline orientation at the beginning of the Little Ice Age, related to the strengthening of the winter monsoon, and a constant progradation rate over the last 1500 years. A decrease in sand supply to the coast in the last few decades due to river dam construction and fluvial sand dredging is inferred, possibly affecting the behaviour of the modern and future shorelines, which can be compared with the less human-influenced past changes reconstructed in this study.

  9. Contamination of drinking water resources in the Mekong delta floodplains: arsenic and other trace metals pose serious health risks to population.

    PubMed

    Buschmann, Johanna; Berg, Michael; Stengel, Caroline; Winkel, Lenny; Sampson, Mickey L; Trang, Pham Thi Kim; Viet, Pham Hung

    2008-08-01

    This study presents a transnational groundwater survey of the 62,000 km(2) Mekong delta floodplain (Southern Vietnam and bordering Cambodia) and assesses human health risks associated with elevated concentrations of dissolved toxic elements. The lower Mekong delta generally features saline groundwater. However, where groundwater salinity is <1 g L(-)(1) Total Dissolved Solids (TDS), the rural population started exploiting shallow groundwater as drinking water in replacement of microbially contaminated surface water. In groundwater used as drinking water, arsenic concentrations ranged from 0.1-1340 microg L(-)(1), with 37% of the studied wells exceeding the WHO guidelines of 10 microg L(-)(1) arsenic. In addition, 50% exceeded the manganese WHO guideline of 0.4 mg L(-)(1), with concentrations being particularly high in Vietnam (range 1.0-34 mg L(-)(1)). Other elements of (minor) concern are Ba, Cd, Ni, Se, Pb and U. Our measurements imply that groundwater contamination is of geogenic origin and caused by natural anoxic conditions in the aquifers. Chronic arsenic poisoning is the most serious health risk for the ~2 million people drinking this groundwater without treatment, followed by malfunction in children's development through excessive manganese uptake. Government agencies, water specialists and scientists must get aware of the serious situation. Mitigation measures are urgently needed to protect the unaware people from such health problems.

  10. Two-year intervention trial to control of fish-borne zoonotic trematodes in giant gourami (Osphronemus goramy) and striped catfish (Pangasianodon hypophthalmus) in nursery ponds in the Mekong Delta, Vietnam.

    PubMed

    Madsen, H; Thien, P C; Nga, H T N; Clausen, J H; Dalsgaard, A; Murrell, K D

    2015-12-01

    Fish-borne zoonotic trematode parasites (FZT) pose a food safety and public health problem in Vietnam. The transmission cycle is complex as domestic animals, especially dogs, cats, fish-eating birds and pigs together with humans serve as reservoir hosts and contribute to FZT egg contamination of aquaculture ponds and the environment. This intervention trial was conducted to determine the effectiveness of various on-farm interventions, including reduction in FZT egg contamination through treatment of infected people and domestic animals, reduction in snail density through mud removal from aquaculture ponds prior to fish stocking, and various other measures in reducing FZT infection in juvenile striped catfish (Pangasianodon hypophthalmus) and giant gourami (Osphronemus goramy). Interventions were implemented on 5 farms for each fish species during production cycles in 2009 and 2010 while 5 similar farms for each species served as control. For both fish species, both prevalence and intensity of infection did not differ significantly between intervention and non-intervention farms prior to the interventions. The interventions significantly reduced both prevalence and intensity of FZT infection in the juvenile fish compared to control ponds. For giant gourami, odds of infection in intervention ponds was 0.13 (95% CL: 0.09-0.20; p<0.001) of that in non-intervention ponds after the 2009 trial and 0.07 (0.03-0.14; p<0.001) after the 2010 trial. For striped catfish, these figures were 0.17 (0.08-0.35; p<0.001) after the 2009 trial while after the 2010 trial all ponds with interventions were free from infection. Metacercariae intensity (no. of metacercariae/fish) in giant gourami from intervention ponds was 0.16 (0.11-0.23; p<0.001) of that in fish from non-intervention ponds after the 2009 trial and 0.07 (0.04-0.15; p<0.001) after the 2010 trial; for striped catfish these figures were 0.18 (0.09-0.36; p<0.001) and 0.00 (confidence limits not estimated), respectively. The

  11. Linking rapid erosion of the Mekong River delta to human activities.

    PubMed

    Anthony, Edward J; Brunier, Guillaume; Besset, Manon; Goichot, Marc; Dussouillez, Philippe; Nguyen, Van Lap

    2015-10-08

    As international concern for the survival of deltas grows, the Mekong River delta, the world's third largest delta, densely populated, considered as Southeast Asia's most important food basket, and rich in biodiversity at the world scale, is also increasingly affected by human activities and exposed to subsidence and coastal erosion. Several dams have been constructed upstream of the delta and many more are now planned. We quantify from high-resolution SPOT 5 satellite images large-scale shoreline erosion and land loss between 2003 and 2012 that now affect over 50% of the once strongly advancing >600 km-long delta shoreline. Erosion, with no identified change in the river's discharge and in wave and wind conditions over this recent period, is consistent with: (1) a reported significant decrease in coastal surface suspended sediment from the Mekong that may be linked to dam retention of its sediment, (2) large-scale commercial sand mining in the river and delta channels, and (3) subsidence due to groundwater extraction. Shoreline erosion is already responsible for displacement of coastal populations. It is an additional hazard to the integrity of this Asian mega delta now considered particularly vulnerable to accelerated subsidence and sea-level rise, and will be exacerbated by future hydropower dams.

  12. Linking rapid erosion of the Mekong River delta to human activities

    PubMed Central

    Anthony, Edward J.; Brunier, Guillaume; Besset, Manon; Goichot, Marc; Dussouillez, Philippe; Nguyen, Van Lap

    2015-01-01

    As international concern for the survival of deltas grows, the Mekong River delta, the world’s third largest delta, densely populated, considered as Southeast Asia’s most important food basket, and rich in biodiversity at the world scale, is also increasingly affected by human activities and exposed to subsidence and coastal erosion. Several dams have been constructed upstream of the delta and many more are now planned. We quantify from high-resolution SPOT 5 satellite images large-scale shoreline erosion and land loss between 2003 and 2012 that now affect over 50% of the once strongly advancing >600 km-long delta shoreline. Erosion, with no identified change in the river’s discharge and in wave and wind conditions over this recent period, is consistent with: (1) a reported significant decrease in coastal surface suspended sediment from the Mekong that may be linked to dam retention of its sediment, (2) large-scale commercial sand mining in the river and delta channels, and (3) subsidence due to groundwater extraction. Shoreline erosion is already responsible for displacement of coastal populations. It is an additional hazard to the integrity of this Asian mega delta now considered particularly vulnerable to accelerated subsidence and sea-level rise, and will be exacerbated by future hydropower dams. PMID:26446752

  13. Peat formation concentrates arsenic within sediment deposits of the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Stuckey, Jason W.; Schaefer, Michael V.; Kocar, Benjamin D.; Dittmar, Jessica; Pacheco, Juan Lezama; Benner, Shawn G.; Fendorf, Scott

    2015-01-01

    Mekong River Delta sediment bears arsenic that has been released to groundwater under anaerobic conditions over the past several thousand years. The oxidation state, speciation, and distribution of arsenic and the associated iron bearing phases are crucial determinants of As reactivity in sediments. Peat from buried mangrove swamps in particular may be an important host, source, or sink of arsenic in the Mekong Delta. The total concentration, speciation, and reactivity of arsenic and iron were examined in sediments in a Mekong Delta wetland by X-ray fluorescence spectrometry (XRF), X-ray absorption spectroscopy (XAS), and selective chemical extractions. Total solid-phase arsenic concentrations in a peat layer at a depth of 6 m below ground increased 10-fold relative to the overlying sediment. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that arsenic in the peat was predominantly in the form of arsenian pyrite. Arsenic speciation in the peat was examined further at the micron-scale using μXRF and μX-ray absorption near-edge structure (XANES) spectroscopy coupled with principal component analysis. The multiple energy μXRF mapping and μXANES routine was repeated for both iron and sulfur phase analyses. Our μXRF/μXANES analyses confirm arsenic association with pyrite - a less reactive host phase than iron (hydr)oxides under anaerobic conditions. The arsenian pyrite likely formed upon deposition/formation of the peat in a past estuarine environment (∼5.5 ka BP), a process that is not expected under current geochemical conditions. Presently, arsenian pyrite is neither a detectable source nor a sink for aqueous arsenic in our sediment profile, and under present geochemical conditions represents a stable host of As under the reducing aquifer conditions of the Mekong Delta. Furthermore, organic carbon within the peat is unable to fuel Fe(III) reduction, as noted by the persistence of goethite which can be reduced microbially with the

  14. Sediment dynamics in the Mekong Delta: impacts of planned hydropower development, climate change and sea level rise

    NASA Astrophysics Data System (ADS)

    Van Manh, Nguyen; Viet Dung, Nguyen; Nghia Hung, Nguyen; Kummu, Matti; Merz, Bruno; Apel, Heiko

    2016-04-01

    The Mekong Delta is under threat due to human activities endangering the livelihood of millions of people. Hydropower development, climate change and the combined effects of sea level rise and deltaic subsidence are the main drivers impacting future flow regimes, sedimentation patterns and erosion in the Mekong Delta. In order to estimate the individual and combined impacts of the different drivers sensitivity-based scenario simulations were performed. The hydraulic processes and the sediment transport and deposition in the Mekong delta including the Tonle Sap Lake was simulated with a quasi-2D hydrodynamic for a baseline (2000-2010) and a future (2050-2060) period. For each driver a plausible range of future states was determined based on existing literature and studies. The ranges were discretized into different levels, resulting in 216 combinations of driver combinations. The results thus cover all plausible future pathways of sediment dynamics in the delta based on current knowledge. The results indicate that hydropower development dominates the changes in floodplain sediment dynamics of the Mekong Delta, while sea level rise has the smallest effect. The floodplains of the Vietnamese Mekong Delta are much more sensitive to the changes compared to other subsystems of the delta. The median changes of the three drivers combined indicate that the inundation extent would increase slightly, but the overall floodplain sedimentation would decrease by approximately 40%, and the suspended sediment load to the South China Sea would diminish to half of the current rates. The maximum changes in all drivers would mean a nearly 90% reduction of delta sedimentation, and a 95% reduction of the suspended sediment reaching the sea. These findings provide new and valuable information on the possible future development of floodplain hydraulics and sedimentation in the Mekong Delta, and identify the areas that are most vulnerable to these changes. This, in turn, provides a

  15. Mekong Floods Fill Tonle Sap

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The monsoon season in Southeast Asia brings recurring, often devastating floods to countries in the region, but these floods also play a necessary role in the region's water cycle. These MODIS images centered on Cambodia reveal extensive flooding of the Mekong River, which comes in from Laos in the north, to the right of center in the images, and flows south through Cambodia and southeast through Vietnam to empty into the South China Sea. The true-color image shows the brownish, sediment-laden floodwaters filling the Mekong Delta in southern Cambodia and Vietnam on September 15, 2001. The false color image above has been enhanced to bring out the contrast between the floodwaters and the lands, with sediment-carrying floodwaters in purple. Sediment can be seen flowing into the South China Sea as well. This year's floods have affected over a million people, and 100 people have been killed in Vietnam alone. The monsoon floods bring not only devastation, but renewal. The large body of water just left of center in Cambodia is the Tonle Sap. This shallow lake plays a changing role in the regional water cycle. During the dry season, the stream-fed Tonle Sap drains via the Tonle Sab River into the Mekong River. During the wet season (June-November), flooding of the Mekong reverses the course of the Tonle Sab, roughly tripling the lake's size from about 3000 km2 to about 10,000. When the dry season returns, the lake once again begins to drain into the Mekong Delta, where it provides a flow of fresh water that balances the intrusion of salty seawater into the delta's agricultural lands. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  16. Forecast Mekong

    USGS Publications Warehouse

    Turnipseed, D. Phil

    2011-01-01

    Forecast Mekong is part of the U.S. Department of State's Lower Mekong Initiative, which was launched in 2009 by Secretary Hillary Clinton and the Foreign Ministers of Cambodia, Laos, Thailand, and Vietnam to enhance partnerships between the U.S. and the Lower Mekong River countries in the areas of environment, health, education, and infrastructure. The U.S. Geological Survey (USGS) is working in close cooperation with the U.S. Department of State to use research and data from the Lower Mekong Basin to provide hands-on results that will help decision makers in Lower Mekong River countries in the planning and design for restoration, conservation, and management efforts in the basin.

  17. Documenting Fine-Sediment Import and Export for Two Contrasting Mesotidal Flats Sediment Flux through the Mekong Tidal River, Delta and Mangrove Shoreline Instrumentation to Support Investigation of Large Tropical Deltas

    DTIC Science & Technology

    2013-09-30

    Contrasting Mesotidal Flats Sediment Flux through the Mekong Tidal River, Delta and Mangrove Shoreline Instrumentation to Support Investigation of Large...scales), and thereby validate localized measurements and numerical models of sediment transport for diverse tidal systems (tidal flats, mangrove forests...Sediment Flux through the Mekong Tidal River, Delta and Mangrove Shoreline Instrumentation to Support Investigation of Large Tropical Deltas 5a. CONTRACT

  18. Sedimentary processes on the Mekong subaqueous delta: Clay mineral and geochemical analysis

    NASA Astrophysics Data System (ADS)

    Xue, Zuo; Paul Liu, J.; DeMaster, Dave; Leithold, Elana L.; Wan, Shiming; Ge, Qian; Nguyen, Van Lap; Ta, Thi Kim Oanh

    2014-01-01

    Sedimentary processes on the inner Mekong Shelf were investigated by examining the characteristics of sediments sampled in gravity cores at 15 locations, including grain size, clay mineralogy, sediment accumulation rates, and the elemental and stable carbon isotopic composition of organic matter (atomic C/N ratios and δ13C). Deltaic deposits exhibit contrasting characteristics along different sides of the delta plain (South China Sea, SCS hereafter, to the east and Gulf of Thailand, GOT hereafter, to the west) as well as on and off the subaqueous deltaic system. On one hand, cores recovered from the subaqueous delta in the SCS/GOT are consisted of poorly/well sorted sediments with similar/different clay mineral assemblage with/from Mekong sediments. Excess 210Pb profiles, supported by 14C chronologies, indicate either "non-steady" (SCS side) or "rapid accumulation" (GOT side) processes on the subaqueous delta. The δ13C and C/N ratio indicate a mixture of terrestrial and marine-sourced organic matter in the deltaic sediment. On the other hand, cores recovered from areas with no deltaic deposits or seaward of the subaqueous delta show excess 210Pb profiles indicating "steady-state" accumulation with a greater proportion of marine-sourced organic matter. Core analysis's relevance with local depositional environment and previous acoustic profiling are discussed.

  19. Future sediment dynamics in the Mekong Delta floodplains: Impacts of hydropower development, climate change and sea level rise

    NASA Astrophysics Data System (ADS)

    Manh, Nguyen Van; Dung, Nguyen Viet; Hung, Nguyen Nghia; Kummu, Matti; Merz, Bruno; Apel, Heiko

    2015-04-01

    The Mekong Delta is under threat due to human activities that are endangering livelihood of millions of people. Hydropower development, climate change and the combined effects of sea level rise and deltaic subsidence are the main drivers impacting future flow regimes and sedimentation patterns in the Mekong Delta. We develop a sensitivity-based approach to assess the response of the floodplain hydrology and sediment dynamics in the delta to these drivers. A quasi-2D hydrodynamic model of suspended sediment dynamics is used to simulate the sediment transport and sediment deposition in the delta, including Tonle Sap Lake, for a baseline (2000-2010) and a future (2050-2060) period. For each driver we derive a plausible range of future states and discretize it into different levels, resulting in 216 combinations. Our results thus cover all plausible future pathways of sediment dynamics in the delta based on current knowledge. Our results indicate that hydropower development dominates the changes in floodplain sediment dynamics of the Mekong Delta, while sea level rise has the smallest effect. The floodplains of the Vietnamese Mekong Delta are much more sensitive to the changes compared to the other subsystems of the delta. The median changes of the three drivers combined indicate that the inundation extent would increase slightly, but the overall floodplain sedimentation would decrease by approximately 40%, and the sediment load to the South China Sea would diminish to half of the current rates. The maximum changes in all drivers would mean a nearly 90% reduction of delta sedimentation and a 95% reduction of the sediment reaching the sea. Our findings provide new and valuable information on the possible future development of floodplain hydraulics and sedimentation in the Mekong Delta and identify the areas that are most vulnerable to these changes.

  20. Forecast Mekong: 2011 update

    USGS Publications Warehouse

    Turnipseed, D. Phil

    2011-01-01

    In 2009, U.S. Secretary of State Hillary R. Clinton joined with the Foreign Ministers of Cambodia, Laos, Thailand, and Vietnam in launching the Lower Mekong Initiative to enhance U.S. engagement with the Lower Mekong countries in the areas of environment, health, education, and infrastructure. Part of the Lower Mekong Initiative, the U.S. Geological Survey's Forecast Mekong project is engaging the United States in scientific research relevant to environmental issues in the Lower Mekong River countries and is staying the course in support of the Mekong Nations with a suite of new projects for 2011.

  1. A study of the climate change impacts on fluvial flood propagation in the Vietnamese Mekong Delta

    NASA Astrophysics Data System (ADS)

    Dang Tri, V. P.; Popescu, I.; van Griensven, A.; Solomatine, D.; Trung, N. H.; Green, A.

    2012-06-01

    The present paper investigated what would be the flood propagation in the Vietnamese Mekong Delta (VMD), due to different projected climate change scenarios, if the 2000 flood event (the most recent highest flood in the history) was taken as a base for computation. The analysis herein was done to demonstrate the particular complexity of the flood dynamics. The future floods, on short term horizon, year 2050, were studied by considering the projected sea level rise (SLR) (+30 cm). At the same time, future flood hydrograph changes at Kratie, Cambodia were applied for the upstream boundary condition. In this study, the future flood hydrograph was separated into two scenarios in which: (i) Scenario 1 was projected in 2050 according to the adjusted regional climate model without any development in the Upper Mekong Basin; and, (ii) Scenario 2 was projected as in Scenario 1 but with the development of the Upper Mekong Basin after 2030. Analyses were done to identify the high sensitive areas in terms of flood conditions (i.e. with and without flood) according to the uncertainty of the projection of both the upstream and downstream boundary conditions. In addition, due to the rice-dominated culture in the VMD, possible impacts of flood on the rice-based farming systems were analysed.

  2. Tidal regime deformation by sea level rise along the coast of the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Nhan, Nguyen Huu

    2016-12-01

    The future of river deltas is believed to depend mainly on sea level rise (SLR) and on the processes controlling the adaptation of the substrate to human impacts. The deltas are increasingly deprived of riverine sediment by river diversion, dams, dykes and the destruction of wetlands, and they are often sinking due to mining for groundwater, gas and petroleum. The relative sea level rise is causing severe negative impacts in many river deltas worldwide. With continuously rising sea levels, this impact is expected to increase over time. The increased risk of delta flooding caused by tidal deformation associated with SLR in shallow coastal waters has received less attention. In this study, we demonstrate this effect for the case of the Mekong Delta where this study suggests that the maximum tidal water level and the tidal amplitude are increasing while the tidal phase at the coast is decreasing. In addition, the maximum water levels is rising faster than SLR because the tides themselves are modified by SLR. This effect is particularly pronounced for semi-diurnal tides and less so for diurnal tides. Similar effects may prevail for river deltas with extensive shallow coastal waters elsewhere in the world and deserve further investigation.

  3. Population dynamics of shrimps in littoral marine waters of the Mekong Delta, south of Viet Nam.

    PubMed

    Dinh, T D; Moreau, J; Van, M V; Phuong, N T; Toan, V T

    2010-07-15

    The population dynamics of eight commercial species of shrimp (Haliporoides sibogae, Harpiosquilla harpax, Metapenaeus affinis, Metapenaeus brevicornis, Metapenaeus tenuipes, Parapenaeopsis cultrirostris, Parapenaeopsis gracillima and Parapenaeus maxilipedo) distributed in littoral marine zone of the Mekong Delta were investigated. Length-based stock assessment using FiSAT II software package was used to assess the growth and mortality parameters: Asymptotic size (L8), growth coefficient (K), total (Z) and natural (M) mortality, exploitation rate (E), recruitment pattern, current probability of capture and selectivity of fishing gears. Yield-per-recruit analyses were carried out showing different levels of the exploitation. Results showed that the maximum sustainable yield would be reached for an exploitation rate higher than the current one for each population. However, the size of first capture should be increased for every population. The findings indicated that the current exploitations of shrimp populations distributed in littoral marine zone of the Mekong Delta are under exploitation level for maximum sustainable yield; however, all the shrimp populations are subject to growth over-exploitation.

  4. Arsenic Concentrations in Rice and Associated Health Risks Along the Upper Mekong Delta, Cambodia

    NASA Astrophysics Data System (ADS)

    Barragan, L.; Seyfferth, A.; Fendorf, S.

    2011-12-01

    The consumption of arsenic contaminated food, such as rice, can be a significant portion of daily arsenic exposure, even for populations already exposed through drinking water. While arsenic contamination of rice grains has been documented in parts of Southern Asia, (e.g. Bangladesh), little research has been conducted on arsenic contamination of Cambodian-grown rice. We collected rice plant samples at various locations within the upper Mekong River Delta near Phnom Penh, Cambodia, and we analyzed total arsenic concentrations in plant digests of grains, husk, and straw. In addition, we used CaCl2-, DTPA-, and oxalate-extractable arsenic to define plant-available soil pools. We found variability of arsenic concentration in the plants, with grain arsenic ranging from 0.046 to 0.214 μg g-1; other researchers have shown that concentrations higher than 0.1 μg g-1 could be a concern for human health. Although more extensive sampling is needed to assess the risk of arsenic exposure from rice consumption on a country-wide basis, our work clearly illustrates the risk within regions of the Mekong Delta.

  5. Vietnamese Women in Academic Leadership: Experiences of Mid-Level Women Leaders in Universities and Colleges in the Mekong Delta

    ERIC Educational Resources Information Center

    Dang, Ngoc Lan Thi

    2012-01-01

    Academic women in the Mekong Delta (MD) in southern Viet Nam remain underrepresented in key leadership positions and other positions of power and influence in their institutions. This situation exists regardless of various local, national, and international policies on gender equality and the implementation of numerous action plans, strategies,…

  6. 2500 years of changing shoreline accretion rates at the mouths of the Mekong River delta

    NASA Astrophysics Data System (ADS)

    Besset, Manon; Tamura, Toru; Anthony, Edward; Brunier, Guillaume; Saito, Yoshiki; Dussouillez, Philippe; Lap Nguyen, Van; Ta, Oahn

    2016-04-01

    The Mekong River delta prograded rapidly in a relatively sheltered bight in the South China Sea under the influence of high fluvial sediment supply 5300 to 3500 years ago, developing from an estuary into a delta. This >200 km seaward growth resulted in increasing exposure of the delta to ocean waves that led to a more wave-influenced mode of progradation characterized by the construction of numerous sets of beach ridges in the eastern sector of the delta, which shows a system of multiple distributary mouths. The growth pattern of this river-mouth sector over the last 2500 years has been determined from OSL dating of these beach-ridge deposits, while the most up-to-date trends (1950-2014) have been highlighted from the analysis of maps and satellite images. The OSL ages show that the area of the delta in the mouths sector remained nearly constant till about 500 yr BP, following which significant accretion occurred, possibly in response to changes in catchment land-use and monsoon rainfall and attendant river water and sediment discharge. A fine-tuned analysis of changes since 1950 shows dominant but fluctuating accretion, with two periods of erosion. The first (1965-1973) occurred in the course of the second Indochina war, and the second more recently from 2003 to 2011, followed by mild recovery between 2011 and 2014. These fluctuations most likely reflect changes in sediment supply caused by the vicissitudes of war and its effect on vegetation cover, as well as variations in monsoon rainfall and discharge, and, for the most recent period, massive sand mining in the river and deltaic channels. Accretion of the mouths sector has gone apace, over the same recent multi-decadal period, with large-scale erosion of the muddy shores of the delta in the western South China Sea and the Gulf of Thailand, thus suggesting that the mouths sector may be increasingly sequestering sediment to the detriment of the rest of the delta shoreline. The accretion in the mouths sector is

  7. Determining the solid phases hosting arsenic in Mekong Delta sediments

    NASA Astrophysics Data System (ADS)

    Wucher, M.; Stuckey, J. W.; McCurdy, S.; Fendorf, S.

    2011-12-01

    The major river systems originating from the Himalaya deposit arsenic bearing sediment into the deltas of South and Southeast Asia. High rates of sediment and organic carbon deposition combined with frequent flooding leads to anaerobic processes that release arsenic into the pore-water. Arsenic concentrations in the groundwater of these sedimentary basins are often above the World Health Organization drinking water standard of 10 μg As L-1. As a result, 150 million people are at risk of chronic arsenic poisoning through water and rice consumption. The composition of the iron bearing phases hosting the arsenic in these deltaic sediments is poorly understood. Here we implemented a suite of selective chemical extractions to help constrain the types of arsenic bearing solid phases, which were complimented with synchrotron-based X-ray absorption spectroscopy and X-ray diffraction analyses to define the arsenic and iron mineralogy of the system. Sediment cores were collected in triplicate from a seasonally-inundated wetland in Cambodia at depths of 10, 50, 100, and 150 centimeters. We hypothesize that (i) arsenic will be predominantly associated with iron oxides, and (ii) the ratio of crystalline to amorphous iron oxides will increase with sediment depth (and age). We performed four selective extractions in parallel to quantify the various pools of arsenic. First, 1 M MgCl2 was used to extract electrostatically-bound arsenic (labile forms) from the sediment. Second, 1 M NaH2PO4 targeted strongly adsorbed arsenic. Third, 1 M HCl was used to liberated arsenic coprecipitated with amorphous Fe/Mn oxides, carbonates, and acid-volatile sulfides. Finally, a dithionite extraction was used to account for arsenic associated with reducible Fe/Mn oxides. Through this work, we identified the composition of the phases hosting arsenic at various depths through the soil profile, improving our understanding of how arsenic persists in the aquifer. In addition, defining the arsenic and

  8. Understanding transitions in rice paddy extent and management in the Vietnamese Mekong River Delta using Landsat data

    NASA Astrophysics Data System (ADS)

    Kontgis, C. P.; Schneider, A.; Ozdogan, M.

    2014-12-01

    Rice is a staple food crop for the majority of the world's population, yet paddy fields are threatened by urban expansion, climate change, and degraded agricultural land. For example, Vietnam, the second largest exporter of rice globally, grows most of its rice in the Mekong River Delta at the country's southern tip, yet this low-lying and heavily populated area is proving susceptible to land cover changes in the area. To properly monitor and manage the rice crops in this region, remote sensing of satellite imagery has been particularly useful; however, most efforts to map regional paddy area utilize coarse resolution MODIS or AVHRR data since the high temporal resolution of these datasets can overcome missing data issues due to clouds. Here, we aim to map the landscape using finer-scale Landsat data by generating dense time stacks over multiple growing seasons. First, we exploit dense stacks of data for circa 2000 and circa 2010 to classify rice using vegetation trajectories (EVI and NDWI). Next, these pixel-based rice maps are combined with image-based segments (generated using the open-source Mean-shift region-growing segmentation algorithm, which has been proven to optimally identify clusters within an image) to generate a polygon-based rice map using the majority rule. Results show that this method can map rice paddy agriculture with over 90% accuracy at a much finer spatial resolution than has ever been produced. Finally, this work also aims to differentiate between double- and triple-cropped rice paddies in the region, again by exploiting EVI trajectories, in an effort to determine how management practices have changed over the decade-long study period. Increasing the number of annual cropping cycles over the area can lead to soil degradation and lower yields per harvest, albeit larger total annual yields, so monitoring these practices is vital to understanding the sustainability of these agricultural systems.

  9. The influence of delta formation mechanism on geotechnical property sequence of the late Pleistocene-Holocene sediments in the Mekong River Delta.

    PubMed

    Hoang, Truong Minh; van Lap, Nguyen; Oanh, Ta Thi Kim; Jiro, Takemura

    2016-11-01

    The aim of the study was to characterize a variety of microstructure development-levels and geotechnical property sequences of the late Pleistocene-Holocene deposits in the Mekong River delta (MRD), and the paper furthermore discusses the influences of delta formation mechanisms on them. The survey associated the geotechnical engineering and the sedimentary geology of the late Pleistocene-Holocene deposits at five sites and also undifferentiated Pleistocene sediments. A cross-section which was rebuilt in the delta progradation-direction and between the Mekong and Bassac rivers represents the stratigraphy. Each sedimentary unit was formed under a different delta formation mechanism and revealed a typical geotechnical property sequence. The mechanical behaviors of the sediment succession in the tide-dominated delta with significant fluvial-activity and material source tend to be more cohesionless soils and strengths than those in the tide- and wave-dominated delta and even the coast. The particular tendency of the mechanical behavior of the deposit succession can be reasonably estimated from the delta formation mechanism. The characteristics of the clay minerals from the Mekong River produced the argillaceous soil which does not have extremely high plasticity. The microstructure development-levels are low to very high indicating how to choose hydraulic conductivity value, k, for estimating overconsolidation ratio, OCR, by the piezocone penetration tests (CPTU). The OCR of sediments in the delta types strangely change with depth but none less than 1. The post-depositional processes significantly influenced the microstructure development, particularly the dehydrating and oxidizing processes.

  10. Applications of multispectral imagery to water resources development planning in the lower Mekong Basin (Khmer Republic, Laos, Thailand and Viet-Nam)

    NASA Technical Reports Server (NTRS)

    Vankiere, W. J.

    1973-01-01

    The use of ERTS imagery for water resources planning in the lower Mekong Basin relates to three major issues: (1) it complements data from areas, which have been inaccessible in the past because of security; this concerns mainly forest cover of the watersheds, and geological features, (2) it refines ground surveys; this concerns mainly land forms, and soils of existing and planned irrigation perimeters, and (3) it provides new information, which would be almost or entirely impossible to detect with ground surveys or conventional photography; this concerns the mechanism of flooding and drainage of the delta; siltation of the Great Lake and mapping of acidity, possibly also of salinity, in the lower delta; sedimentation and fisheries in the Mekong Delta estuarine areas.

  11. Forecast Mekong: navigating changing waters

    USGS Publications Warehouse

    Powell, Janine

    2011-01-01

    The U.S. Geological Survey (USGS) is using research and data from the Mekong River Delta in Southeast Asia to compare restoration, conservation, and management efforts there with those done in other major river deltas, such as the Mississippi River Delta in the United States. The project provides a forum to engage regional partners in the Mekong Basin countries to share data and support local research efforts. Ultimately, Forecast Mekong will lead to more informed decisions about how to make the Mekong and Mississippi Deltas resilient in the face of climate change, economic stresses, and other impacts.

  12. Intertidal nematode communities in the Mekong estuaries of Vietnam and their potential for biomonitoring.

    PubMed

    Quang, Ngo Xuan; Chau, Nguyen Ngoc; Smol, Nic; Prozorova, Larisa; Vanreusel, Ann

    2016-02-01

    Nematode communities in eight Mekong estuaries were investigated during the dry season. The aim of the study was to identify the structure and the diversity of the communities in relation to the main environmental characteristics. In each estuary, three to four intertidal sampling stations were identified at regular distances from the mouth to up to 45 km land inward. The nematode communities showed a strong correlation with sediment composition and to a lesser degree with chlorophyll a concentrations. Multivariate analysis resulted in the identification of four types of communities. We identified two types of Desmodora communities in the sandy mouth stations and two types of Parodontophora communities in the silty sand stations. One of the silt associated communities showed a preference for higher chlorophyll a concentrations, resulting in higher densities and higher diversity, mainly of monhysterid species. Because of the strong association between community structure and sediment composition, nematodes are a meaningful tool for monitoring changes in their environment. In case their community deviates from what is expected based on sediment, it may serve as an early warning for disturbance.

  13. Integrated Biogeochemical and Hydrologic Processes Driving Arsenic Release from Shallow Sediments to Groundwaters of the Mekong Delta

    SciTech Connect

    Kocar, Benjamin D.; Polizzotto, Matthew L.; Benner, Shawn G.; Ying, Samantha C.; Ung, Mengieng; Ouch, Kagna; Samreth, Sopheap; Suy, Bunseang; Phan, Kongkea; Sampson, Michael; Fendorf, Scott

    2008-11-01

    Arsenic is contaminating the groundwater of Holocene aquifers throughout South and Southeast Asia. To examine the biogeochemical and hydrological processes influencing dissolved concentrations and transport of As within soils/sediments in the Mekong River delta, a ~50 km₂ field site was established near Phnom Penh, Cambodia, where aqueous As concentrations are dangerously high and where groundwater retrieval for irrigation is minimal. Dissolved As concentrations vary spatially, ranging up to 1300 µg/L in aquifer groundwater and up to 600 µg/L in surficial clay pore water. Groundwaters with high As concentrations are reducing with negligible dissolved O₂ and high concentrations of Fe(II), NH⁺₄ , and dissolved organic C. Within near-surface environments, these conditions are most pronounced in sediments underlying permanent wetlands, often found within oxbow channels near the Mekong River. There, labile C, co-deposited with As-bearing Fe (hydr)oxides under reducing conditions, drives the reductive mobilization (inclusive of Fe and As reduction) of As. Here, conditions are described under which As is mobilized from these sediments, and near-surface As release is linked to aquifer contamination over long time periods (100s to 1000s of years). Site biogeochemistry is coupled with extensive hydrologic measurements, and, accordingly, a comprehensive interpretation of spatial As release and transport within a calibrated hydraulic flow-field is provided of an As-contaminated aquifer that is representative of those found throughout South and Southeast Asia.

  14. Assessment of colloidal copper speciation in the Mekong River Delta using diffusive gradients in thin film techniques

    NASA Astrophysics Data System (ADS)

    Seah, Kahyee Cary; Qasim, Ghulam Hussain; Hong, Yong Seok; Kim, Eunsuk; Kim, Kyung Tae; Han, Seunghee

    2017-03-01

    Colloidal Cu speciation along the salinity gradient in the Mekong River Delta was investigated using diffusive gradients in thin films (DGT) probes equipped with diffusive layers that had nominal pore sizes of 390 nm (DGT390) and 45 nm (DGT45). An open pore gel made of 1.5% agarose was used for the 390 nm pore size cutoff, and a restricted gel made of 40% acrylamide monomer was used for the 45 nm cutoff. When DGT390 and DGT45 were deployed in a 0.01 M NaNO3 solution for up to four days, the mean ratio of Cu accumulated in DGT390 to dissolved Cu (dCu) (<0.45 μm) was 1.0, and Cu accumulated in DGT45 to dCu was 0.98. By contrast, when DGT390 and DGT45 probes were deployed in Mekong River water of salinity 0, the ratio increased with increasing deployment time, from 0.15 to 1.0 for DGT390 and from 0.02 to 0.52 for DGT45, for four days. This demonstrates that the slow dissociation of colloidal Cu complex confines the rapid accumulation of colloidal Cu in DGT45, implying the potential of DGT probes for colloidal Cu monitoring. The same DGT probes were deployed in the Mekong River in order to test its in situ applicability. The colloidal fraction, determined by the difference between dCu and Cu accumulated in DGT45, ranged from 67% to 77% of dCu at the low-salinity sites but from 8.7% to 9.1% of dCu at the brackish sites. A large amount of particle suspension typically found at the salinity front of the Mekong River seemed to play a critical role in the transport of Cu by providing dCu and organic colloids from suspended sediment. Based on our test results, employing DGT probes is likely a promising method for monitoring colloidal Cu in natural water.

  15. Relation between oceanic conditions in the South China Sea and water levels within and along the Vietnamese Mekong River Delta

    NASA Astrophysics Data System (ADS)

    Uehara, K.; Tanaka, A.; Saito, Y.; Tamura, T.; Nguyen, V. L.; Ta, T. K.

    2013-12-01

    Seasonal water level change within and around the Vietnamese Mekong River Delta (MRD) has been analyzed to understand the impact of climate change in the South China Sea on river flooding within the MRD. It was found that the sea level variability along the deltaic coast has high coherence with the strength of offshore oceanic currents which seasonally reverse their direction under the SE Asian monsoon climate, indicating that the coastal sea level is linked with offshore currents through a geostrophic relation. It was also suggested that the temporal pattern of water levels in the middle reaches of the MRD, 80-100km apart from the river mouth, was influenced not only by upstream information but also by the downstream sea level change. These results indicates that the climatic change in the oceanic current field may influence the occurrence of flooding within the MRD especially during the NE monsoon season when the sea level is high.

  16. Reactive and unreactive iron minerals hosting arsenic within seasonal wetland sediments of the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Stuckey, J.; Schaefer, M.; Lezama, J.; Dittmar, J.; Fendorf, S.

    2013-12-01

    Millions of people in the deltaic regions of S/SE Asia regularly consume arsenic contaminated groundwater. Within the Mekong Delta of Cambodia, for example, arsenic persists within the groundwater despite being flushed by several pore volumes of recharge. The identity and reactivity of the minerals contributing to the persistence of arsenic in the deltaic aquifers remain elusive. Here we seek to define the molecular form of the arsenic and its host phases along defined flow paths in seasonally saturated wetlands: i) a grassland flooded for ~ 3 - 4 months of the year (Grassland) and ii) an abandoned river channel saturated for ~ 5 - 6 months (Oxbow). Sediment cores were retrieved by pounding aluminum cores into a fresh profile exposed by successive excavation. The cores were sealed with melted wax in the field and stored at 4 °C until processed. Depths of 0.2 to 6 m were sampled at the Grassland site and 0.2 to 4 m at the Oxbow site. Sediments were dried under 95%N2/5%H2 atmosphere. A 1 M HCl extraction dissolving the 'reactive' iron (predominantly poorly crystalline iron oxides) solubilized 3 - 7 % of the total iron in the Grassland site and 8 - 41 % in the Oxbow site. A citrate-bicarbonate-dithionite (CBD) extraction was performed to extract reducible iron (predominantly iron oxides), accounting for 35 - 50 % of the total iron in the Grassland site and 27 - 44 % in the Oxbow site. Correspondingly, least squares fitting of k3 - weighted chi(k) iron extended X-ray absorption fine structure (EXAFS) spectra showed that goethite and hematite together comprised 34 - 50 % of the iron mineralogy in the mineral sediments of the Grassland site and 24 - 38 % of those in the Oxbow site. The remaining iron minerals present were predominantly silicates. Iron EXAFS spectra were obtained for the post-CBD extracted sediments, theoretically containing only non-reducible iron. Least squares fitting of the bulk (pre-CBD extracted) sediments was performed a second time with the

  17. Persistent organic pollutants in wetlands of the Mekong Basin

    USGS Publications Warehouse

    Triet, Tran; Barzen, Jeb Anthony; Choowaew, Sansanee; Engels, Jon Michael; Ni, Duong Van; Mai, Nguyen Anh; Inkhavilay, Khamla; Soben, Kim; Sethik, Rath; Gomotean, Bhuvadol; Thuyen, Le Xuan; Kyi, Aung; Du, Nguyen Huy; Nordheim, Richard; Lam, Ho Si Tung; Moore, Dorn M.; Wilson, Scott

    2013-01-01

    In this study, the presence and concentration of persistent organic pollutants (POP) were assessed in surface sediments collected from a wide variety of wetlands located throughout the Mekong Basin in Myanmar, Lao People’s Democratic Republic (PDR), Thailand, Cambodia, and Vietnam. Of the 39 POPs tested in 531 sediment samples, dichlorodiphenyltrichloroethane (DDT) and its metabolites endosulfan, hexachlorobenzene (HCB), and endrin were most commonly detected. Even though DDT was banned in the 1990s, some use of DDT may still be occurring in the Mekong Basin. The amount of metabolites for DDT—dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD)—found, however, suggests that use of DDT is on the decline throughout the region. HCB and endrin were found distributed broadly throughout the Mekong Basin but not in high amounts. The concentration and distribution of endosulfan and its metabolites represent a serious problem requiring further study and management action. While the total loading of POPs in wetland sediments of the Mekong Basin was generally low, hotspot sites occurred where concentrations exceeded established ecological risk thresholds. For example, wetlands of the open, dry dipterocarp forest of northern Cambodia and Vietnam as well as wetlands in the Mekong Delta of Vietnam contained high concentrations of some POPs. High concentrations of POPs were detected in some wetlands important for biodiversity conservation. Hotspots identified in wetlands such as the Tonle Sap not only had concentrations of DDT and DDE that exceeded Canadian and U.S. benchmarks, but fauna sampled in the area also showed high degrees of bioaccumulation of the same substances. Further and more extensive attention to monitoring POP presence in water birds, fish, and other aquatic organisms is warranted because of the bioaccumulation of these chemicals at higher levels in the food chain. This study represents a collaboration of eight universities from

  18. Diversity and As-adsorption properties of Mn(II)-oxidizing bacteria within tropical wetlands of the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Ying, S. C.; Kocar, B. D.; Fendorf, S.; Francis, C. A.

    2007-12-01

    Manganese (Mn) and iron (Fe) oxides are ubiquitous minerals that occur under similar redox conditions in terrestrial systems and have high sorptive capacities for many trace metals, including arsenic (As). In most natural environments, Fe oxidation is dominated by abiotic processes, while Mn oxides are primarily formed via bacterial Mn(II) oxidation, and both processes can profoundly impact the mobility of metal(loid) contaminants. Deciphering the mechanisms involved in arsenic transport within soils and sediments is essential for aiding many Southeast Asian countries, including Cambodia, where naturally occurring As is in groundwater at concentrations well above the WHO recommended limit. Although numerous past studies have characterized the effects of As adsorption onto Fe and Mn oxides individually, it is unknown whether, in the presence of both oxides, there is preferential adsorption of As onto one oxide over the other. In the present study, we examine the competitive retention of As(III) and As(V) on goethite and biogenic Mn oxides using Donnan membranes--where each oxides is isolated by a semi-permeable membrane through which arsenic can migrate. Mn(II)-oxidizing bacteria, isolated from several Mn-rich sites along the Mekong River and wetland areas within the Mekong delta, were dominated by a diverse array of Bacillus strains that rapidly oxidize Mn(II) within three to five days in liquid culture. The results of this study not only expand our knowledge of the diversity and biogeochemical importance of terrestrial Mn(II)-oxidizing bacteria, but also contribute to our understanding the relative impact of Fe and Mn oxides on arsenic retention within natural wetlands.

  19. Impacts of dyke development in flood prone areas in the Vietnamese Mekong Delta to downstream flood hazard

    NASA Astrophysics Data System (ADS)

    Khanh Triet Nguyen, Van; Dung Nguyen, Viet; Fujii, Hideto; Kummu, Matti; Merz, Bruno; Apel, Heiko

    2016-04-01

    The Vietnamese Mekong Delta (VMD) plays an important role in food security and socio-economic development of the country. Being a low-lying coastal region, the VMD is particularly susceptible to both riverine and tidal floods, which provide, on (the) one hand, the basis for the rich agricultural production and the livelihood of the people, but on the other hand pose a considerable hazard depending on the severity of the floods. But despite of potentially hazardous flood, the area remain active as a rice granary due to its nutrient-rich soils and sediment input, and dense waterways, canals and the long standing experience of the population living with floods. In response to both farmers' requests and governmental plans, the construction of flood protection infrastructure in the delta progressed rapidly in the last twenty years, notably at areas prone to deep flooding, i.e. the Plain of Reeds (PoR) and Long Xuyen Quadrangle (LXQ). Triple rice cropping becomes possible in farmlands enclosed by "full-dykes", i.e. dykes strong and high enough to prevent flooding of the flood plains for most of the floods. In these protected flood plains rice can be grown even during the peak flood period (September to November). However, little is known about the possibly (and already alleged) negative impacts of this fully flood protection measure to downstream areas. This study aims at quantifying how the flood regime in the lower part of the VMD (e.g. Can Tho, My Thuan, …) has been changed in the last 2 recent "big flood" events of 2000 and 2011 due to the construction of the full-dyke system in the upper part. First, an evaluation of 35 years of daily water level data was performed in order to detect trends at key gauging stations: Kratie: upper boundary of the Delta, Tan Chau and Chau Doc: areas with full-dyke construction, Can Tho and My Thuan: downstream. Results from the Mann-Kendall (MK) test show a decreasing trend of the annual maximum water level at 3 stations Kratie, Tan

  20. Thermochronology of mineral grains in the Red and Mekong Rivers, Vietnam: Provenance and exhumation implications for Southeast Asia

    NASA Astrophysics Data System (ADS)

    Clift, Peter D.; Carter, Andrew; Campbell, Ian H.; Pringle, Malcolm S.; van Lap, Nguyen; Allen, Charlotte M.; Hodges, Kip V.; Tan, Mai Thanh

    2006-10-01

    Sand samples from the mouths of the Red and Mekong Rivers were analyzed to determine the provenance and exhumation history of their source regions. U-Pb dating of detrital zircon grains shows that the main sources comprise crust formed within the Yangtze Craton and during the Triassic Indosinian Orogeny. Indosinian grains in the Mekong are younger (210-240 Ma) than those in the Red River (230-290 Ma), suggesting preferential erosion of the Qiangtang Block of Tibet into the Mekong. The Red River has a higher proportion of 700-800 Ma grains originally derived from the Yangtze Craton. 40Ar/39Ar dating of muscovite grains demonstrates that rocks cooled during the Indosinian Orogeny are dominant in both rivers, although the Mekong also shows a grain population cooling at 150-200 Ma that is not seen in the Red River and which is probably of original Qiangtang Block origin. Conversely, the Red River contains a significant mica population (350-500 Ma) eroded from the Yangtze Craton. High-grade metamorphic rocks exposed in the Cenozoic shear zones of southeast Tibet-Yunnan are minority sources to the rivers. However, apatite and zircon fission track ages show evidence for the dominant sources, especially in the Red River, only being exhumed through the shallowest 5-3 km of the crust since ˜25 Ma. The thermochronology data are consistent with erosion of recycled sediment from the inverted Simao and Chuxiong Basins, from gorges that incise the eastern flank of the plateau. Average Neogene exhumation rates are 104-191 m/Myr in the Red River basin, which is within error of the 178 ± 35 m/Myr estimated from Pleistocene sediment volumes. Sparse fission track data from the Mekong River support the Ar-Ar and U-Pb ages in favoring tectonically driven rock uplift and gorge incision as the dominant control on erosion, with precipitation being an important secondary influence.

  1. Blood flukes (Digenea: Aporocotylidae) of walking catfishes (Siluriformes: Clariidae): new genus and species from the Mekong River (Vietnam) with comments on related catfish aporocotylids.

    PubMed

    Truong, Triet Nhat; Bullard, Stephen A

    2013-07-01

    Nomasanguinicola canthoensis gen. et sp. n. infects the branchial vessels of bighead catfish, Clarias macrocephalus Günther (Siluriformes: Clariidae), in the Mekong River near Can Tho, southern Vietnam. Nomasanguinicola differs from all other genera of fish blood flukes (Digenea: Aporocotylidae) by the combination of lacking body spines and by having an anterior sucker with two flanking columns of large denticles, an intestine comprising several short papilla-like caeca, an inverse U-shaped uterus, and an ootype located near the separate genital pores. The new species has an ootype that is posterior to the level of the female genital pore. That feature most easily differentiates it from the only other putative aporocotylid species having an anterior sucker with two flanking columns of large denticles, Plehniella dentata Paperna, 1964 and Sanguinicola clarias Imam, Marzouk, Hassan et Itman, 1984, which have an ootype that is lateral (P. dentata) or anterior (S. clarias) to the level of the female genital pore. These two species apparently lack extant type materials, infect North African catfish, Clarias gariepinus (Burchell), and herein are considered incertae sedis, but likely comprise species of Nomasanguinicola. An updated list of hosts, sites of infection and geographic localities for the six species and three genera of blood flukes that mature in catfishes is provided. The new species is the first fish blood fluke recorded from Vietnam and only the third reported from a walking catfish (Clariidae).

  2. Population subdivision in Siamese mud carp Henicorhynchus siamensis in the Mekong River basin: implications for management.

    PubMed

    Adamson, E A S; Hurwood, D A; Baker, A M; Mather, P B

    2009-10-01

    A molecular approach was employed to investigate stock structure in Siamese mud carp Henicorhynchus siamensis populations collected from 14 sites across mainland south-east Asia, with the major focus being the lower Mekong River basin. Spatial analysis of a mitochondrial DNA fragment (ATPase 6 and 8) identified four stocks in the Mekong River basin that were all significantly differentiated from a population in the nearby Khlong River, Thailand. In the Mekong River basin, populations in northern Lao People's Democratic Republic and northern Thailand represent two independent stocks, and samples from Thai tributaries group with those from adjacent Mekong sites above the Khone Falls to form a third stock. All sites below the Khone Falls constituted a single vast stock that includes Cambodia and the Mekong Delta in Vietnam. While H. siamensis is considered currently to undertake extensive annual migrations across the Mekong River basin, the data presented here suggest that natural gene flow may occur over much more restricted geographical scales within the basin, and hence populations may need to be managed at finer spatial scales than at the whole-of-drainage-basin level.

  3. Closing the irrigation deficit in Cambodia: Implications for transboundary impacts on groundwater and Mekong River flow

    NASA Astrophysics Data System (ADS)

    Erban, Laura E.; Gorelick, Steven M.

    2016-04-01

    Rice production in Cambodia, essential to food security and exports, is largely limited to the wet season. The vast majority (96%) of land planted with rice during the wet season remains fallow during the dry season. This is in large part due to lack of irrigation capacity, increases in which would entail significant consequences for Cambodia and Vietnam, located downstream on the Mekong River. Here we quantify the extent of the dry season "deficit" area in the Cambodian Mekong River catchment, using a recent agricultural survey and our analysis of MODIS satellite data. Irrigation of this land for rice production would require a volume of water up to 31% of dry season Mekong River flow to Vietnam. However, the two countries share an aquifer system in the Mekong Delta, where irrigation demand is increasingly met by groundwater. We estimate expansion rates of groundwater-irrigated land to be >10% per year in the Cambodian Delta using LANDSAT satellite data and simulate the effects of future expansion on groundwater levels over a 25-year period. If groundwater irrigation continues to expand at current rates, the water table will drop below the lift limit of suction pump wells, used for domestic supply by >1.5 million people, throughout much of the area within 15 years. Extensive groundwater irrigation jeopardizes access for shallow domestic water supply wells, raises the costs of pumping for all groundwater users, and may exacerbate arsenic contamination and land subsidence that are already widespread hazards in the region.

  4. Acoustical facies analysis at the Ba Lat delta front (Red River Delta, North Vietnam)

    NASA Astrophysics Data System (ADS)

    van den Bergh, G. D.; van Weering, Tj. C. E.; Boels, J. F.; Duc, D. M.; Nhuan, M. T.

    2007-02-01

    A shallow penetrating, high-resolution acoustic study was performed in the Ba Lat delta, the major distributary of the Red River System in Northern Vietnam. An acoustic facies map was constructed and the various facies types were validated through analysis of bottom sediments, by a study of gravity cores collected at 22 stations. Analysis of the acoustic profiles and gravity cores revealed the presence of an asymmetrical, S to SW prograding prodelta lobe, in accordance with the prevailing longshore currents to the S. The southern part of this prodelta is detached from the protruding Ba Lat delta front. The prodelta is dominated by muddy sediments with minor thin (<5 cm) sandy and silty layers. The coarser-grained layers decrease in abundance away from the Ba Lat river mouth. Offshore, the modern delta deposits are characterized by an off-lapping contact over a semi-prolonged bottom reflector lacking any sub-bottom reflectors. This semi-prolonged bottom reflector is correlated with sandy deposits of presumably Early Holocene age. Bottom and coastal erosion is restricted to two areas N and SW of the Ba Lat. Erosion in the North is inferred to be due to reduced sediment supply as a result of shifting in 1971 of the main outlet to its present, more southern location. The erosional area along the Hai Hau coast SW of the Ba Lat also has experienced a reduction in sediment supply in the course of the 20th century, when the local Song Vop distributary channel became less active and was completely dammed in the 1970s. Most sediment supplied by the Ba Lat at present bypasses the Hai Hau erosional coastal zone, as the active part of the Ba Lat prodelta is detached from the coast SW of the Ba Lat. An active, NNE-SSW trending fault system with surface expression is located along the offshore edge of the prodelta, and is linked to deeper fault structures in this active neotectonic region. Subsurface reflectors are folded in the vicinity of the fault.

  5. Reactivity and speciation of mineral-associated arsenic in seasonal and permanent wetlands of the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Stuckey, Jason W.; Schaefer, Michael V.; Benner, Shawn G.; Fendorf, Scott

    2015-12-01

    Millions of people in the deltaic regions of S/SE Asia regularly consume As contaminated groundwater. Arsenic persists within these groundwaters despite being flushed by several pore volumes of recharge, indicative of an in situ solid phase source. Despite the importance of this solid phase source, the identity and reactivity of the minerals hosting and releasing As in the deltaic aquifers remain poorly constrained. Here we seek to define the chemistry and reactivity of As and its host minerals in aquifer sediments recharged by both seasonally saturated and permanent wetlands in the Mekong Delta of Cambodia. Sediment cores were retrieved to depths of up to 30 m. Selective extractions on near-surface sediments (to depths of 4-6 m) indicate that more than a third (27-50%) of the Fe in the profile is "reducible" (citrate-bicarbonate-dithionite-extractable) - nominally consisting of Fe(III) oxides. The Fe(III) oxide fraction was approximately the same under seasonal wetlands (mean = 39%) compared with sediments from beneath permanent wetlands (mean = 37%). Correspondingly, Fe K-edge extended X-ray absorption fine structure (EXAFS) spectra analysis indicates that the Fe mineral phases are predominantly goethite and hematite (30-50%). Analysis of solid phase As speciation by X-ray absorption near edge structure (XANES) spectroscopy showed arsenate in the shallowest sediments (upper 1 and 4 m of seasonal and permanent wetlands), and arsenite and/or As sulfides as the dominant phases in the deeper sediments. The reducible As fraction ranged from 17% to 42% of the total As at both sites. The exception was found in a peat layer at 6 m beneath the seasonal wetland, in which only 1% of the total As was reducible. Arsenian pyrite was the predominant form of As in the peat. Thus, a pool of As hosted by reducible mineral phases persists in sediments below both the seasonal and permanently saturated wetland sites.

  6. Shoreline changes at the mouths of the Mekong River delta over the last 50 years: fluctuating sediment supply and shoreline cells

    NASA Astrophysics Data System (ADS)

    Anthony, E.; Besset, M.; Brunier, G.; Dussouillez, P.; Dolique, F.; Nguyen, V. L.; Goichot, M.

    2014-12-01

    River delta shorelines may be characterized by complex patterns of sediment transport and sequestering at various timescales in response to changes in sediment supply, hydrodynamic conditions, and deltaic self-organization. While being good indicators of delta stability, these changes also have important coastal management and defence implications. These aspects are examined with reference to the mouths of the Mekong River delta, the world's third largest delta, backbone of the Vietnamese economy and home to nearly 20 million people. We conducted an analysis of shoreline fluctuations over the last five decades using low-resolution Landsat (1973-2014), very high-resolution SPOT 5 (2003-2011) satellite imagery, topographic maps (1950, 1965), and field hydrodynamic and shoreline topographic measurements. The results show that the 250 km-long river-mouth sector of the delta shoreline has been characterized by overall accretion but with marked temporal and spatial variations. The temporal pattern is attributed to fluctuations in sediment supply due to both human activities and natural variations in catchment sediment loads (e.g., 2000-2003), and natural adjustments in delta-plain sediment storage and delivery to the coast. The spatial pattern is indicative of discrete sediment cells that may be a response to an overall decreasing sand supply, especially since 2003, following increasingly massive riverbed mining with concomitant losses in channel-bed sand. Field measurements show the prevalence of mesotidal bar-trough beaches characterized by sand migration to the southwest in response to energetic dry-season monsoon waves. Beaches underfed as a result of both wave-energy gradients and possible diminishing sand supply from the adjacent river mouths are eroded to feed accreting beaches. Understanding this cell pattern has important implications in terms of: (1) interpreting past patterns of shoreline translation involved in the construction of successive beach ridges that

  7. Sediment Trapping Pathways and Mechanisms through the Mekong Tidal River and Subaqueous Delta

    DTIC Science & Technology

    2013-09-30

    strive to understand how the delicate balance of ebb and flood sediment fluxes is maintained to create tidal flat and mangrove complexes, and...subaqueous delta on the inner continental shelf, and sediment sinks within vegetated/ mangrove shoreline complexes. Our overall hypothesis is that sediment... Mangrove /Vegetated Intertidal Areas. Along the main stem tidal river and coastal banks may be shorelines lined with vegetation ( mangroves at the

  8. Flood loss assessment in Can Tho City, Vietnam

    NASA Astrophysics Data System (ADS)

    Do, T. C.; Kreibich, H.

    2012-04-01

    Floods are recurring events in the Lower Mekong Basin resulting in loss of life and property, causing damage to agriculture and rural infrastructure, and disrupting social and economic activities. Flood management and mitigation has become a priority issue at the national and regional levels. Besides, it is expected that large areas of the Mekong delta, the Red River delta and the central coast will be flooded by sea-level rise due to climate change. Can Tho City is ranked under the five most flood-tide-influenced cities of Vietnam. It is the biggest city in the Mekong delta and it is located near the Hau river. Like other region of the Mekong delta, Can Tho suffers due to floods from upstream and flood tides from the sea. In the flood season large rural areas of the city are flooded, particularly during tidal days. Flood risk management policy includes preparative measures for living with floods and to minimise the damage caused by floods as well as to take advantage of floods for sustainable development. An intensive literature review, including administrative reports as well as expert interviews have been undertaken to gain more insight into flood characteristics, their consequences and risk mitigation. Therefore, flood damaging processes and trends have been reviewed for Can Tho City and the Mekong Basin in Vietnam. Additionally, suitable flood damage estimation methodologies have been collected as important input for flood risk analyses. On this basis it has been investigated which flood risk mitigation and management strategies promise to be effective in Can Tho City, Vietnam.

  9. Evidence of Water Quality Degradation in Lower Mekong Basin Revealed by Self-Organizing Map.

    PubMed

    Chea, Ratha; Grenouillet, Gaël; Lek, Sovan

    2016-01-01

    To reach a better understanding of the spatial variability of water quality in the Lower Mekong Basin (LMB), the Self-Organizing Map (SOM) was used to classify 117 monitoring sites and hotspots of pollution within the basin identified according to water quality indicators and US-EPA guidelines. Four different clusters were identified based on their similar physicochemical characteristics. The majority of sites in upper (Laos and Thailand) and middle part (Cambodia) of the basin were grouped in two clusters, considered as good quality water with high DO and low nutrient levels. The other two clusters were mostly composed of sites in Mekong delta (Vietnam) and few sites in upstream tributaries (i.e., northwestern Thailand, Tonle Sap Lake, and swamps close to Vientiane), known for moderate to poor quality of water and characterized by high nutrient and dissolved solid levels. Overall, we found that the water in the mainstream was less polluted than its tributaries; eutrophication and salinity could be key factors affecting water quality in LMB. Moreover, the seasonal variation of water quality seemed to be less marked than spatial variation occurring along the longitudinal gradient of Mekong River. Significant degradations were mainly associated with human disturbance and particularly apparent in sites distributed along the man-made canals in Vietnam delta where population growth and agricultural development are intensive.

  10. Evidence of Water Quality Degradation in Lower Mekong Basin Revealed by Self-Organizing Map

    PubMed Central

    Chea, Ratha; Grenouillet, Gaël; Lek, Sovan

    2016-01-01

    To reach a better understanding of the spatial variability of water quality in the Lower Mekong Basin (LMB), the Self-Organizing Map (SOM) was used to classify 117 monitoring sites and hotspots of pollution within the basin identified according to water quality indicators and US-EPA guidelines. Four different clusters were identified based on their similar physicochemical characteristics. The majority of sites in upper (Laos and Thailand) and middle part (Cambodia) of the basin were grouped in two clusters, considered as good quality water with high DO and low nutrient levels. The other two clusters were mostly composed of sites in Mekong delta (Vietnam) and few sites in upstream tributaries (i.e., northwestern Thailand, Tonle Sap Lake, and swamps close to Vientiane), known for moderate to poor quality of water and characterized by high nutrient and dissolved solid levels. Overall, we found that the water in the mainstream was less polluted than its tributaries; eutrophication and salinity could be key factors affecting water quality in LMB. Moreover, the seasonal variation of water quality seemed to be less marked than spatial variation occurring along the longitudinal gradient of Mekong River. Significant degradations were mainly associated with human disturbance and particularly apparent in sites distributed along the man-made canals in Vietnam delta where population growth and agricultural development are intensive. PMID:26731522

  11. The China Factor in U.S.-Vietnam Relations

    DTIC Science & Technology

    2012-03-01

    02/22/blogging-while-vietnamese; Fan Hongxing, Liu Chang, and Wang Huicong, “Vietnam Makes Use of South China Sea Issue To Rope in Big-Power...Mekong by holding back silt and preventing the downstream flow of alluvial needed to fertilize the delta, enrich the soil, wash out salts, and limit...The New York Times, 23 Apr 2010, www.nytimes.com/2010/04/24/world/asia/24navy.html. Fan Hongxing, Liu Chang, and Wang Huicong, “Vietnam Makes Use

  12. Forecast Mekong 2012: Building scientific capacity

    USGS Publications Warehouse

    Stefanov, James E.

    2012-01-01

    In 2009, U.S. Secretary of State Hillary R. Clinton joined the Foreign Ministers of Cambodia, Laos, Thailand, and Vietnam in launching the Lower Mekong Initiative to enhance U.S. engagement with the countries of the Lower Mekong River Basin in the areas of environment, health, education, and infrastructure. The U.S. Geological Survey Forecast Mekong supports the Lower Mekong Initiative through a variety of activities. The principal objectives of Forecast Mekong include the following: * Build scientific capacity in the Lower Mekong Basin and promote cooperation and collaboration among scientists working in the region. * Provide data, information, and scientific models to help resource managers there make informed decisions. * Produce forecasting and visualization tools to support basin planning, including climate change adaptation. The focus of this product is Forecast Mekong accomplishments and current activities related to the development of scientific capacity at organizations and institutions in the region. Building on accomplishments in 2010 and 2011, Forecast Mekong continues to enhance scientific capacity in the Lower Mekong Basin with a suite of activities in 2012.

  13. February 2012 workshop jumpstarts the Mekong Fish Monitoring Network

    USGS Publications Warehouse

    Andersen, Matthew E.; Ainsley, Shaara M.

    2012-01-01

    The Mekong River in Southeast Asia travels through a basin rich in natural resources. The river originates on the northern slope of the world's tallest mountains, the Himalaya Range, and then drops elevation quickly through steep mountain gorges, tumbling out of China into Myanmar (Burma) and the Lao People's Democratic Republic (Lao PDR). The precipitous terrain of Lao PDR and Thailand generates interest in the river and its tributaries for hydropower development. The terrain, soils, water, and climate make it one of the world's most biologically rich regions. The Mekong's bounty is again on display in the Mekong River Delta, where rice production has successfully been increased to high levels making Vietnam second only to Thailand as the world's largest rice exporters. At least 800 fish species contribute to the natural resource bounty of the Mekong River and are the basis for one of the world's most productive fisheries that provide the primary protein source to more than 50 million people. Against this backdrop of rich natural resources, the U.S. Geological Survey (USGS) is working with the consulting firm FISHBIO, colleagues from the international Delta Research and Global Observation Network (DRAGON) Institute, and a broad contingent of Southeast Asian representatives and partners from abroad to increase knowledge of the Mekong River fisheries and to develop the capacity of permanent residents to investigate and understand these fisheries resources. With the Lower Mekong Basin (LMB) region facing the likelihood of significant environmental changes as a result of both human activities and global climate change, enhancing environmental understanding is critical. To encourage cooperation among the LMB scientists and managers in the study of the Mekong River's fisheries, FISHBIO and the USGS, with generous support from the U.S. State Department, hosted a workshop in Phnom Penh, Cambodia, in February 2012. Workshop participants were from Lao PDR, Thailand

  14. Bathymetry of the Hong and Luoc River Junction, Red River Delta, Vietnam, 2010

    USGS Publications Warehouse

    Kinzel, Paul J.; Nelson, Jonathan M.; Toan, Duong Duc; Thanh, Mung Dinh; Shimizu, Yasuyuki

    2012-01-01

    The U.S. Geological Survey, in collaboration with the Water Resources University in Hanoi, Vietnam, conducted a bathymetric survey of the junction of the Hong and Luoc Rivers. The survey was done to characterize the channel morphology of this delta distributary network and provide input for hydrodynamic and sediment transport models. The survey was carried out in December 2010 using a boat-mounted multibeam echo sounder integrated with a global positioning system. A bathymetric map of the Hong and Luoc River junction was produced which was referenced to the datum of the Trieu Duong tide gage on the Luoc River.

  15. Effects of lead, molybdenum, rubidium, arsenic and organochlorines on spermatogenesis in fish: monitoring at Mekong Delta area and in vitro experiment.

    PubMed

    Yamaguchi, Sonoko; Miura, Chiemi; Ito, Aki; Agusa, Tetsuro; Iwata, Hisato; Tanabe, Shinsuke; Tuyen, Bui Cach; Miura, Takeshi

    2007-06-05

    To estimate the influence of water contaminants on fish reproduction in the Mekong Delta area, we sampled cultivated male catfish (Pangasianodon hypophthalmus), investigated testicular development, and measured persistent organic pollutants (POPs) and trace element levels in muscle and liver, respectively. Various testes sizes were observed although sampling took place during a short period. Histological analysis revealed that all developmental stages of germ cells were observed in catfish with large testis, whereas only necrotic spermatogonia but no other germ cells were observed in catfish with small testis. In small testis, furthermore, vacuolization and hypertrophy of Sertoli cells were observed. Measurement of POPs in muscle and trace elements in liver demonstrated that there were negative correlations between GSI and the concentrations of Pb, Mo, Rb and As. To clarify possible direct effects of Pb, Mo, Rb and As on spermatogenesis in fish, we investigated the effects of these trace elements on spermatogenesis using in vitro testicular organ culture of Japanese eel (Anguilla japonica). Treatment with each of the trace elements alone did not affect spermatogenesis. However, treatment with 10(-7)M of Pb, 10(-5) and 10(-4)M of Mo, 10(-5)-10(-3)M of Rb or 10(-5)M of As inhibited the spermatogenesis induced by 11-ketotestosterone (11KT). Furthermore, treatment with 10(-4)M of As in combination with 11KT caused necrosis of testicular fragments. Taken together, these results are consistent with the hypothesis that Pb, Mo, Rb and As can exert inhibitory effects on spermatogenesis in catfish inhabiting the Mekong Delta area.

  16. Characterization and interaction of precipitation, river water and groundwater in the Vietnamese Mekong Delta - A case study in the Plain of Reeds

    NASA Astrophysics Data System (ADS)

    Duy Nguyen, Le; Heidbüchel, Ingo; Merz, Bruno; Apel, Heiko

    2016-04-01

    An understanding of the interactions between surface water and groundwater systems in the Vietnamese Mekong Delta (VMD) is important not only for water resources planning and management, but also for the livelihood of the majority of the population in the delta. Precipitation and ground water, but also river water is used as drinking water in the communes of the Delta. Particularly the ground water is increasingly exploited, but the important processes like river - aquifer interaction and ground water recharge rates are largely unknown. This study thus aims at the characterization of processes between the different water resources. For this the different water sources were sampled over longer time periods and analysed for isotopic composition (2H, 18O). Additionally surface and ground water levels were recorded, as well as the temperature profile at and under the river bed in order to identify the river-ground water interaction. First results indicate that the isotopic composition and the local meteoric water line of the precipitation is very similar to the GNIP data for Bangkok, indicating similar isotopic sequestration and origin of the rainfall in the region (near ocean areas of SE-Asia). The isotopic composition of precipitation and river water exhibits a strong seasonal signal indicating the monsoonal influence. During the monsoon season both precipitation and river water is depleted in stable isotopes, while the dry season shows an enriched composition. This also indicates the different composition of the river water over the seasons. During the rainy season the portion of rain water, i.e. surface runoff stemming from the Mekong basin but also direct rainfall contribution in the Mekong Delta is considerably larger, as expected. The enriched composition during the dry season indicates a larger ground water, i.e. base flow portion, but also a generally higher evaporation due to the lower atmospheric moisture. The isotopic composition of the ground water differs

  17. Planning practice in support of economically and environmentally sustainable roads in floodplains: the case of the Mekong delta floodplains.

    PubMed

    Douven, Wim; Buurman, Joost

    2013-10-15

    Road development in relatively undisturbed floodplain systems, such as the floodplains of the Mekong River, will impact hydraulics and interrupt the natural flow of water. This affects the ecology and environment, and the livelihoods of people who depend on fishing and agriculture. On the other hand, floods can severely damage road infrastructure in years with large floods and can cause high annual maintenance costs. Improving road development practices in floodplains is a complex, multidimensional task involving hydraulic and geotechnical analysis, ecosystem analysis, socio-economic analysis, policy analysis, etc. This paper analyses the planning practice of road development and rehabilitation and how this practice can be improved in support of economically and environmentally sustainable roads in floodplains. It is concluded that although ample technical, planning and environmental assessment guidelines exist, guidelines need updating to address cumulative impacts at floodplain level and factors hampering the implementation in guidelines should be addressed in the guideline design (process).

  18. Vietnam.

    PubMed

    1984-05-01

    Attention in this discussion of Vietnam is directed to the following: people; geography; history; government; the economy (agriculture and industry, trade and balance of payments); foreign relations; and relations between the US and Vietnam. In mid-1983 the population was estimated at 57,610,000 with an annual growth rate of 2.4%. Ethnic Vietnamese constitute almost 90% of the population. Various ethnic groups make up the remaining 10% of the population, with approximately 1.2 million Chinese being the most numerous and concentrated in southern Vietnam. The 2nd largest minority, the Montagnards (mountain tribesmen) comprise 2 main ethnolinguistic groups--Malayo Polynesia and Mon-Khmer. The most important political institution in Vietnam is the Vietnamese Communisty Party. All but 4 party Politburo members concurrently hold high positions in the government. The most important powers within the Vietnamese government, as opposed to the Communisty Party, are the executive agencies. Under the overly ambitious initial 5 year plan and the more conservative 1981-85 plan, the Vietnamese have made little progress in raising output and living standards beyond the levels of the 1960s. Guidelines of the 1981-85 plan call for attaining food self sufficiency, strengthening export and consumer industries, as well as the heavy industries that support them, and improving transport and energy production. The US does not have diplomatic relations with Vietnam.

  19. Spatio-temporal analysis of recent groundwater-level trends in the Red River Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Bui, Duong Du; Kawamura, Akira; Tong, Thanh Ngoc; Amaguchi, Hideo; Nakagawa, Naoko

    2012-12-01

    A groundwater-monitoring network has been in operation in the Red River Delta, Vietnam, since 1995. Trends in groundwater level (1995-2009) in 57 wells in the Holocene unconfined aquifer and 63 wells in the Pleistocene confined aquifer were determined by applying the non-parametric Mann-Kendall trend test and Sen's slope estimator. At each well, 17 time series (e.g. annual, seasonal, monthly), computed from the original data, were analyzed. Analysis of the annual groundwater-level means revealed that 35 % of the wells in the unconfined aquifer showed downward trends, while about 21 % showed upward trends. On the other hand, confined-aquifer groundwater levels experienced downward trends in almost all locations. Spatial distributions of trends indicated that the strongly declining trends (>0.3 m/year) were mainly found in urban areas around Hanoi where there is intensive abstraction of groundwater. Although the trend results for most of the 17 time series at a given well were quite similar, different trend patterns were detected in several. The findings reflect unsustainable groundwater development and the importance of maintaining groundwater monitoring and a database in the Delta, particularly in urban areas.

  20. Trace Gas Emissions from Extensive Aquaculture Systems in the Red River Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Beman, J.; Seto, K. C.

    2002-12-01

    The Red River Delta of Vietnam is an area undergoing rapid land use change. Aquaculture development is among the most significant of these transformations, with important economic, social and environmental effects. We explored the potential for managed mangrove' and `converted paddy' aquaculture systems in the Delta to produce and/or consume greenhouse gasses. We measured dissolved concentrations of the radiatively-important trace gasses methane (CH4) and nitrous oxide (N2O), as well as associated parameters. All ponds were super-saturated with CH4, with concentrations ranging from 132-1203 nM, (mean 561 nM) in managed mangrove, and 28-521 nM (mean 110 nM) in converted paddy. Surprisingly, none of the ponds was measurably supersaturated with N2O. Methane fluxes were calculated for all ponds using five well-accepted models of gas flux based on wind speed. Mean flux values ranged from 1.04 to 17.09 mg CH4 m-2 d-1 for managed mangrove, falling somewhere between fluxes reported for natural systems and those receiving sewage inputs. Further measurements should be made in more intensive systems to better understand the potential for trace gas production-particularly N2O-in aquaculture systems.

  1. Bridging the Past with Today's Microwave Remote Sensing: A Case Study of Long Term Inundation Patterns in the Mekong River Delta

    NASA Astrophysics Data System (ADS)

    Jensen, K.; McDonald, K. C.; Schroeder, R.; Tessler, Z. D.

    2015-12-01

    Surface inundation extent and its predictability vary tremendously across the globe. This dynamic is being and has been captured by three general categories of satellite imagery: 1) low-spatial-resolution microwave sensors with global coverage and a long record of observations (e.g., SSM/I), 2) optical sensors with high spatial and temporal resolution and global coverage, but with cloud contamination (e.g. MODIS), and 3) in more ''snapshot'' form by high-resolution synthetic aperture radar (SAR) sensors. We explore the ability to bridge techniques that can exploit the higher spatial resolution of more recent data products back in time with the help of the temporal evolution of lower resolution products. We present a study of long term (20+ year) inundation patterns in the Mekong River Delta using baseline observations from the Surface Water Microwave Product Series (SWAMPS), an inundation area fraction product derived at 25km scale from active and passive microwave instruments (ERS, QuikSCAT, ASCAT, and SSM/I) that spans from Jan. 1992 to Jun. 2015. Every hydrological basin has unique characteristics - such as its topography, land cover / land use, and space-time variability - thus, a downscaling algorithm needs to take into account these idiosyncrasies. We merge SWAMPS with topographical information derived from 30m SRTM DEM, river networks from USGS HydroSHEDS, and assess the best statistical procedure to "learn" from two sets of classified SAR data: (1) L-band imaging radar from ALOS PALSAR, 2007-2010, and (2) C-band imagery from the Sentinel-1 mission (2014 to present). We present a comparison of retrospective downscaled flood extent with Landsat imagery and recent observations from SMAP. With a higher spatial resolution of past flooding extent, we can improve our understanding of how delta surface hydrology responds to local and regional events. This is important both in the short-term for accurate flood prediction, as well as on longer-term planning horizons.

  2. Social and ecological challenges of market-oriented shrimp farming in Vietnam.

    PubMed

    Lan, Ngo Thi Phuong

    2013-01-01

    Vietnam is one of the largest shrimp exporters in the world. Since 2010, Vietnam has earned about two billion dollars annually through shrimp exports. As a fertile area of greatest potential for agricultural production in Vietnam, the Mekong Delta has been a major contributor to the country's achievements, especially in the agricultural sector. During recent decades, trade liberation along with various policies in support of aquaculture has accelerated the development of shrimp production in the Delta. Based on an ethnographic study of shrimp farming in the Mekong Delta of Vietnam, I assert that along with great rewards arising from the expansion of shrimp farming areas, productivity, and export value, the shrimp industry has brought various environmental, economic and social challenges. Consequently, shrimp farming is a risky business and local inhabitants have relied on various strategies to cope with these challenges. Risk mitigation in shrimp production and labor migration are the two important strategies of local inhabitants for securing their livelihoods. Water pollution and poor quality post-larvae shrimp are direct consequences of market-oriented production.

  3. Application of co-anaerobic digester's effluent for sustainable agriculture and aquaculture in the Mekong Delta, Vietnam.

    PubMed

    Nguyen, V C N; Fricke, K

    2015-01-01

    This investigation studied the application of digester effluent from co-digestion of pig manure and spent mushroom substrate as a fertilizer for leaf mustard planting and as feed for Tilapia fish growing. The fish raising experiment was set up in 1 × 1 × 1 m hapa conditions (triplicate for each treatment) with the density of 10 individiual per hapa; the fish weight and length were measured every 10 days for 50 continuous days. The leaf mustard was planted in real conditions at farmer's garden with normal cultivation style, and the weight and length of the plant were measured four times during the growing period. The study result shows that the harvest yield of leaf mustard fertilized by the digester effluent was 5.4 times higher than that by an inorganic fertilizer (IF). In addition to its contribution to a higher yield, the digester effluent accelerated the flower formation and shortened cultivation duration. For Tilapia fish culture, the growing rate of fish in the treatments supplied with 50% digester effluent + 50% commercial food (CF) was not significantly different in comparison to the fish cultivation with 100% CF. The result strongly confirms that the digester effluent from a co-digestion biogas plant of pig dung and spent mushroom compost is possible to be used as an organic fertilizer well for not only vegetable planting but also fish culture.

  4. Aerobic Decomposition and Organic Amendments Effects on Grain Yield of Triple-Cropped Rice in the Mekong Delta, Vietnam

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil aeration during decomposition of incorporated crop residues and application of organic amendments might help improve soil quality and rice yield for sustainable intensive rice production. A field experiment was conducted on triple-cropped rice during three consecutive crops with five treatments...

  5. Managing Tradeoffs between Hydropower and the Environment in the Mekong River Basin

    NASA Astrophysics Data System (ADS)

    Loucks, Daniel P.; Wild, Thomas B.

    2015-04-01

    Hydropower dams are being designed and constructed at a rapid pace in the Mekong/Lancang River basin in Southeast Asia. These reservoirs are expected to trap significant amounts sediment, decreasing much of the river's capability to transport nutrients and maintain its geomorphology and habitats. We apply a simulation model for identifying and evaluating alternative dam siting, design and operating policy (SDO) options that could help maintain more natural sediment regimes downstream of dams and for evaluating the effect of these sediment-focused SDO strategies on hydropower production and reliability. We apply this approach to the planned reservoirs that would prevent a significant source of sediment from reaching critical Mekong ecosystems such as Cambodia's Tonle Sap Lake and the Mekong delta in Vietnam. Model results suggest that various SDO modifications could increase sediment discharge from this site by 300-450% compared to current plans, but a 30-55% loss in short-term annual energy production depending on various configurations of upstream reservoirs. Simulation results also suggest that sediment management-focused reservoir operating policies could cause ecological damage if they are not properly implemented.

  6. Language Education, Economic Development and Participation in the Greater Mekong Subregion

    ERIC Educational Resources Information Center

    Bruthiaux, Paul

    2008-01-01

    The Mekong has long attracted interest although it remains economically insignificant. A group of riparian states known as the Greater Mekong Subregion (GMS)--Cambodia, Laos, Myanmar, Thailand, Vietnam and Yunnan Province (China)--now manage aspects of regional development including trade, water management and education. Standard GMS discourse…

  7. Farm- and flock-level risk factors associated with Highly Pathogenic Avian Influenza outbreaks on small holder duck and chicken farms in the Mekong Delta of Viet Nam.

    PubMed

    Henning, Kate A; Henning, Joerg; Morton, John; Long, Ngo Thanh; Ha, Nguyen Truc; Meers, Joanne

    2009-10-01

    After 11 consecutive months of control, the Mekong Delta in Viet Nam experienced a wave of Highly Pathogenic Avian Influenza (HPAI) H5N1 outbreaks on small holder poultry farms from December 2006 to January 2007. We conducted a retrospective matched case-control study to investigate farm- and flock-level risk factors for outbreak occurrence during this period. Twenty-two case farms were selected from those where clinical signs consistent with HPAI H5N1 had been present and HPAI H5N1 had been confirmed with a positive real-time PCR test from samples obtained from affected birds. For every case farm enrolled, two control farms were selected matched on time of outbreak occurrence, farm location and species. Veterinarians conducted interviews with farmers, to collect information on household demographics, farm characteristics, husbandry practices, trading practices, poultry health, vaccination and biosecurity. Exact stratified logistic regression models were used to assess putative risk factors associated with a flock having or not having a HPAI outbreak. Nested analyses were also performed, restricted to subsets of farms using scavenging, confinement or supplementary feeding practices. Risk of an outbreak of HPAI H5N1 was increased in flocks that had received no vaccination (odds ratio (OR)=20.2; 95% confidence interval (CI): 1.0, +infinity) or only one vaccination (OR=85.2; 95% CI: 6.5, +infinity) of flocks compared to two vaccinations, and in flocks on farms that had family and friends visiting (OR=8.2; 95% CI: 1.0, +infinity) and geese present (OR=11.5; 95% CI: 1.1, +infinity). The subset analysis using only flocks that scavenged showed that sharing of scavenging areas with flocks from other farms was associated with increased risk of an outbreak (OR=10.9; 95% CI: 1.4, 492.9). We conclude that none or only one vaccination, visitors to farms, the presence of geese on farms and sharing of scavenging areas with ducks from other farms increase the risk of HPAI H5N1

  8. Impact of the Hoa Binh Dam (Vietnam) on water and sediment budgets in the Red River basin and delta

    NASA Astrophysics Data System (ADS)

    Vu, D. V.; Ouillon, S.; Tran, D. T.; La, V. C.

    2014-01-01

    The Hoa Binh Dam, located on a tributary of the Red River in Vietnam, has a capacity of 9.45 × 109 m3 and was commissioned in December 1988. Although being important for flood prevention, electricity production, and irrigation in northern Vietnam, the Hoa Binh Dam has also highly influenced the suspended sediment distribution in the lower Red River basin, in the delta and in the coastal zone. Its impact was analysed from 50 yr dataset of water discharge and suspended sediment concentration (1960-2010) and the distribution of water and sediment across the nine mouths of the delta was calculated using the MIKE 11 numerical model before and after the dam settlement. Although water discharge at the delta inlet decreased by only 8.8%, the yearly suspended sediment flux dropped, on average from 119 to 43 × 106 t yr-1 at Son Tay near Hanoi, and from 85 to 35 × 106 t yr-1 in the river mouths. Water regulation has led to decreased water discharge in the wet season and increased water discharge in the dry season. Suspended sediment discharge proportionally increased in northern and southern estuaries and decreased through the main and central Ba Lat mouth. Tidal pumping, which causes a net sediment flux from the coast to the estuary at low discharge, is high in the northern delta, as a consequence of the high tidal range (up to 4.5 m in spring tide; diurnal tide). The shifts in the dynamic and characteristics of the turbidity maximum zone in the Cam-Bach Dang estuary are probably the cause of the enhanced sediment deposition in the Haiphong harbor. Along the coast, the reduced sedimentation rates are coincident with the lower sediment delivery that has been observed since the impoundment of the Hoa Binh Dam.

  9. Impact of the Hoa Binh dam (Vietnam) on water and sediment budgets in the Red River basin and delta

    NASA Astrophysics Data System (ADS)

    Vinh, V. D.; Ouillon, S.; Thanh, T. D.; Chu, L. V.

    2014-10-01

    The Hoa Binh dam (HBD), located on a tributary of the Red River in Vietnam, has a capacity of 9.45 × 109 m3 and was commissioned in December 1988. Although it is important for flood prevention, electricity production and irrigation in northern Vietnam, the Hoa Binh dam has also highly influenced the suspended sediment distribution in the lower Red River basin, in the delta and in the coastal zone. Its impact was analysed from a 50-year data set of water discharge and suspended sediment concentration (1960-2010), and the distribution of water and sediment across the nine mouths of the delta was simulated using the MIKE11 numerical model before and after the dam settlement. Although water discharge at the delta inlet decreased by only 9%, the yearly suspended sediment flux dropped, on average, by 61% at Son Tay near Hanoi (from 119 to 46 × 106 t yr-1). Along the coast, reduced sedimentation rates are coincident with the lower sediment delivery observed since the impoundment of the Hoa Binh dam. Water regulation has led to decreased water discharge in the wet season (-14% in the Red River at Son Tay) and increased water discharge in the dry season (+12% at the same station). The ratios of water and suspended sediment flows, as compared to the total flows in the nine mouths, increased in the northern and southern estuaries and decreased in the central, main Ba Lat mouth. The increasing volume of dredged sediments in the Haiphong harbour is evidence of the silting up of the northern estuary of Cam-Bach Dang. The effect of tidal pumping on enhanced flow occurring in the dry season and resulting from changed water regulation is discussed as a possible cause of the enhanced siltation of the estuary after Hoa Binh dam impoundment.

  10. Managing flow, sediment, and hydropower regimes in the Sre Pok, Se San, and Se Kong Rivers of the Mekong basin

    NASA Astrophysics Data System (ADS)

    Wild, Thomas B.; Loucks, Daniel P.

    2014-06-01

    The Lancang/Mekong River Basin is presently undergoing a period of rapid hydropower development. In its natural undeveloped state, the river transports about 160 million metric tons of sediment per year, maintaining the geomorphologic features of the basin, sustaining habitats, and transporting the nutrients that support ecosystem productivity. Despite the importance of sediment in the river, currently little attention is being paid to reservoir sediment trapping. This study is devoted to assessing the potential for managing sediment and its impact on energy production in the Se San, Sre Pok, and Se Kong tributaries of the Mekong River. These tributaries drain a set of adjacent watersheds that are important with respect to biodiversity and ecological productivity, and serve as a significant source of flow and sediment to the mainstream Mekong River. A daily sediment transport model is used to assess tradeoffs among energy production and sediment and flow regime alteration in multiple reservoir systems. This study finds that eventually about 40%-80% of the annual suspended sediment load may be trapped in reservoirs. Clearly, these reservoirs will affect the rivers' sediment regimes. However, even after 100 years of simulated sedimentation, reservoir storage capacities and hydropower production at most reservoir sites are not significantly reduced. This suggests that the strongest motivation for implementing measures to reduce trapped sediment is their impact not on hydropower production but on fish migration and survival and on sediment-dependent ecosystems such as the Vietnam Delta and Cambodia's Tonle Sap Lake.

  11. Micronutrient composition and nutritional importance of gathered vegetables in Vietnam.

    PubMed

    Ogle, B M; Dao, H T; Mulokozi, G; Hambraeus, L

    2001-11-01

    This article presents the nutrient composition and nutritional contribution of naturally occurring vegetables (NOV) in four villages in Vietnam. The frequency of consumption and quantities eaten were evaluated within the overall diet of 101 and 110 women in the Mekong Delta (flood period and rainy season, respectively) and of 103 women in the Central Highlands (rainy season). The concentrations of Ca, Fe and Zn were analysed in 28 species, and presence of tannins and phytic acid in 19 species. Provitamin carotenoids were determined in 11 species. Over 90% of the women consumed NOV, and they contributed 43, 72 and 75% (Central Highlands, Mekong rainy and Mekong flood period, respectively) of the total quantities of vegetables eaten. Aquatic species such as lpomoea aquatica and Limnocharis flava, and terrestrial vegetables such as Schismattoglottis calyptrata, were among the most commonly consumed vegetables. They were eaten in mean daily quantities exceeding 50 g and had high concentrations of Ca, Fe and beta-carotene. Other major aquatic vegetables included the stems of Eleocharis sp., Nelumbo nucifera and Nymphea lotus, all of which were used as salad vegetables and had relatively low nutrient density. The problems of assessing the current role of NOV due to lack of data on intakes in the context of the overall diets, as well as data on their composition, are addressed.

  12. Cloud Cover and Wildfire Variations in Vietnam and Southeast Asia

    NASA Astrophysics Data System (ADS)

    Lasko, K.

    2015-12-01

    Monitoring fires from space is constrained by cloud cover, particularly in tropical regions. Cloud cover-fire variations were assessed using the CERES SSF1Deg and MODIS active fire (MCD14ML) products in Vietnam and Southeast Asia. Twelve years (2003-2014) of data have been analyzed spatially and temporally at four spatial scales: a) country level; b). 1x1 degree scale; c). land cover type; d). regions. Country-level results suggested Vietnam having the highest monthly cloud cover (72.37%) followed by Cambodia (69.69%), Laos (67.64%), Thailand (67.58%), and Myanmar (59.90%). Strong negative correlation between cloud cover and MODIS active fires has been observed during the biomass burning months (Jan-Apr). Of the different countries, Vietnam also had the lowest monthly fire detections. Pixel by pixel spatial correlation at 1x1 degree suggested negative fire-cloud relationships over the Red River Delta of Vietnam, the forests of northern Laos, and agriculture-dominated peninsulas of Thailand and Myanmar. Among the different land cover types, the average monthly cloud cover varied between 64% - 66%. Further, results from daily data showed the Red River Delta to have consistently more cloud cover (20-40% more) than the Mekong River Delta in Vietnam, with fewer fire detections in the former than the latter. The study highlights potential fire under-detection due to clouds. Our results highlight spatial and temporal variations in cloud-fire relationships and the difficulty of using optical data for fire detection and characterization in persistently cloudy regions.

  13. Detection of HPAI H5N1 viruses in ducks sampled from live bird markets in Vietnam.

    PubMed

    Phan, M Q; Henry, W; Bui, C B; DO, D H; Hoang, N V; Thu, N T; Nguyen, T T; LE, T D; Diep, T Q; Inui, K; Weaver, J; Carrique-Mas, J

    2013-03-01

    In Vietnam, highly pathogenic avian influenza (HPAI) H5N1 infections in poultry often occur without concomitant clinical signs and outbreaks are not consistently reported. Live bird markets represent a convenient site for surveillance that does not rely on farmers' notifications. Two H5N1 surveys were conducted at live bird markets/slaughter points in 39 districts (five provinces) in the Red River, Mekong delta, and central Vietnam during January and May 2011. Oropharyngeal and rectal swab samples from 12 480 ducks were tested for H5N1 by reverse transcription-polymerase chain reaction in pools of five. Traders and stallholders were interviewed using standardized questionnaires; 3·3% of pools tested positive. The highest prevalence (6·6%) corresponded to the Mekong delta, and no H5N1 was detected in the two Red River provinces. The surveys identified key risk behaviours of traders and stallholders. It is recommended that market surveys are implemented over time as a tool to evaluate progress in HPAI control in Vietnam.

  14. Application of discrete choice experiment to assess farmers' willingness to report swine diseases in the Red River Delta region, Vietnam.

    PubMed

    Pham, Hoa T T; Peyre, Marisa; Trinh, Tuyen Quang; Nguyen, Oanh Cong; Vu, Ton Dinh; Rukkwamsuk, Theera; Antoine-Moussiaux, Nicolas

    2017-03-01

    A discrete choice experiment (DCE) is carried out to value socio-economic factors influencing the farmer's decision to report swine diseases and to assess the willingness of farmers to report swine diseases. Data were collected between March and July 2015 in two provinces in the Red River Delta, Northern Vietnam, from 196 pig producers by face-to face interview. A conditional logit model is used to measure the relative importance of the socio-economic factors and calculate the expected probability of disease reporting under changes of levels of these factors. Results of the study indicated that the likelihood of compensation and the type of culling implemented (all or only unrecovered pigs) are the two most important factors influencing farmer reporting. Compensation level, movement restriction and delay in compensation payment also have significant impacts on farmer's decision to report animal disease but they are not as important as the above factors. Three different scenarios including changes in six different factors (attributes) are tested to predict probability of animal disease reporting. Under the current situation (uncertainty of being compensated), only 4% of the farmers would report swine disease outbreak to the official surveillance system if the culling policy involves all pigs in affected farms. This number is increased to 26% if culling in affected farms is restricted to unrecovered pigs only. Ensuring certainty of compensation increases reporting probability by up to 50% and 90% if all or only unrecovered pigs are destroyed, respectively. The results of this study are important for improving the performance and sustainability of swine disease surveillance system in Vietnam.

  15. Characteristics of two duck farming systems in the Mekong Delta of Viet Nam: stationary flocks and moving flocks, and their potential relevance to the spread of highly pathogenic avian influenza.

    PubMed

    Henning, Joerg; Henning, Kate A; Long, Ngo Thanh; Ha, Nguyen Truc; Vu, Le Tri; Meers, Joanne

    2013-03-01

    Ducks are considered to play a major role in the spread of highly pathogenic avian influenza (HPAI) H5N1 in Viet Nam, but detailed information on their management is limited. We distinguished two different systems (1) stationary duck flocks that are not commonly driven to rice fields beyond village boundaries and that are confined overnight on farms and (2) moving duck flocks that are intentionally driven to rice fields beyond village boundaries, that are not returning to home farms for extended periods and that are housed overnight in temporary enclosures in rice paddies. A total of 115 stationary and 22 moving flock farmers were interviewed in 2007 in the Mekong Delta of Viet Nam. Moving duck flocks are larger than stationary flocks, which is indicative of their more commercial production. Moving flock farmers apparently are more aware of HPAI risks than stationary flock farmers, as their flocks are more likely fully vaccinated and have less contact with chickens during scavenging. On the other hand, the spread of HPAI virus between birds might be promoted by moving duck flocks as they repeatedly use transport vehicles and numerous rice paddies for scavenging and are often visited by hatchery owners in the field for purchasing duck eggs. In addition, long distances travelled by moving duck flocks might also result in widespread dissemination of HPAI virus. Further studies are necessary to describe HPAI prevalence and travel patterns of moving duck flocks and to explore the moving duck flock network in detail.

  16. Spotlight: Vietnam.

    PubMed

    1984-02-01

    Vietnam, with 57 million people, ranks as the world's 13th most populous country with much of the population concentrated in the rice producing areas of the coastal lowlands and the Mekong and Red River valleys. Since reunification, economic recovery has been difficult. Following the failure of the 1976-80 5-Year Plan, the 1981-85 Plan calls for increased food production and the attainment of self sufficiency. Part of this policy is the reduction of the population growth rate. Vietnam's labor force is about 70% agricultural, with women making up about 2/3 of the farm work force. Most heavy industry is in the North and, although badly damaged in the war, has regained much of its capacity. Coal continues to be Vietnam's leading export. The country's extensive forests also provide great potential for the lumber industry and Vietnam has recently begun offshore oil production. Yet, recovery has been elusive. Foreign aid now comes from the Soviet Union, China, Eastern Europe, and France. In recent years the foreign trade balance has improved, but there have been some setbacks in food production. Efforts to raise food production by encouraging private development of unused land have not been very successful, partly because of the continuing shortage of fertilizers, farm machinery, and insecticides. It is also likely that economic progress has been retarded by large military expenditures necessitated by the wars with Cambodia and China. 1 of the government's major efforts has been a large scale population redistribution from urban areas to the less densely inhabited provinces. New Economic Zones have been established in these areas in the hope that new residents will become self sufficient as soon as possible. As part of its national policy, the government has set a goal to reduce the rate of population growth to 1.5% by 1981 through the National Family Planning Program. Officially reported crude birthrates reflect a decline in fertility from about 40/1000 population in

  17. Assessment of metal and bacterial contamination in cultivated fish and impact on human health for residents living in the Mekong Delta.

    PubMed

    Chanpiwat, Penradee; Sthiannopkao, Suthipong; Widmer, Kenneth; Himeno, Seiichiro; Miyataka, Hideki; Vu, Ngoc-Ut; Tran, Van-Viet; Pham, Thi-Tuyet-Ngan

    2016-11-01

    Fish is the main source of animal protein and micronutrients for inhabitants in the lower Mekong River basin. Consumption of fish in the basin ranges from 41 to 51 kg capita(-1) year(-1). Thus, concerns of human health impacts caused by daily intake of metals contained in fish, and the incidence of bacterial contamination from Listeria and Escherichia coli have been raised. This study was conducted to 1) determine concentrations of metals, fecal indicator organisms, and Listeria spp. in cultivated common diet fish, and 2) assess human health risks as results of fish consumption on a daily basis. The results showed significant impacts of metal accumulation in fish especially from the intensive aquaculture. Chemical use to promote the rapid allometric growth of fish was expected to be the explanation for this finding. Concentrations of metals contained in different fish species were not statistically different with the exceptions of Na, Mn, and Zn. This might be due to the mobility of elements in aquaculture farms. Listeria and E. coli log CFU/g were 1.36 ± 0.11 (standard error) and 1.57 ± 0.1 s.e., respectively with higher counts observed in samples collected in market sites. Lastly, for human health risk assessment via fish consumption, it was found that hazard quotients of consuming As, Cu, and Zn contained in all fish species could contribute adverse health effects to the local residents (hazard quotients higher than 1). Therefore, risk management measures must be promoted and implemented in all study areas to reduce potential risks to local Vietnamese residents.

  18. Genetic polymorphisms in AS3MT and arsenic metabolism in residents of the Red River Delta, Vietnam.

    PubMed

    Agusa, Tetsuro; Iwata, Hisato; Fujihara, Junko; Kunito, Takashi; Takeshita, Haruo; Minh, Tu Binh; Trang, Pham Thi Kim; Viet, Pham Hung; Tanabe, Shinsuke

    2009-04-15

    To elucidate the role of genetic factors in arsenic (As) metabolism, we studied associations of single nucleotide polymorphisms (SNPs) in As (+3 oxidation state) methyltransferase (AS3MT) with the As concentrations in hair and urine, and urinary As profile in residents in the Red River Delta, Vietnam. Concentrations of total As in groundwater were 0.7-502 mug/l. Total As levels in groundwater drastically decreased by using sand filter, indicating that the filter could be effective to remove As from raw groundwater. Concentrations of inorganic As (IAs) in urine and total As in hair of males were higher than those of females. A significant positive correlation between monomethylarsonic acid (MMA)/IAs and age in females indicates that older females have higher methylation capacity from IAs to MMA. Body mass index negatively correlated with urinary As concentrations in males. Homozygote for SNPs 4602AA, 35991GG, and 37853GG, which showed strong linkage disequilibrium (LD), had higher percentage (%) of dimethylarsinic acid (DMA) in urine. SNPs 4740 and 12590 had strong LD and associated with urinary %DMA. Although SNPs 6144, 12390, 14215, and 35587 comprised LD cluster, homozygotes in SNPs 12390GG and 35587CC had lower DMA/MMA in urine, suggesting low methylation capacity from MMA to DMA in homo types for these SNPs. SNPs 5913 and 8973 correlated with %MMA and %DMA, respectively. Heterozygote for SNP 14458TC had higher MMA/IAs in urine than TT homozygote, indicating that the heterozygote may have stronger methylation ability of IAs. To our knowledge, this is the first study on the association of genetic factors with As metabolism in Vietnamese.

  19. Genetic polymorphisms in glutathione S-transferase (GST) superfamily and arsenic metabolism in residents of the Red River Delta, Vietnam.

    PubMed

    Agusa, Tetsuro; Iwata, Hisato; Fujihara, Junko; Kunito, Takashi; Takeshita, Haruo; Minh, Tu Binh; Trang, Pham Thi Kim; Viet, Pham Hung; Tanabe, Shinsuke

    2010-02-01

    To elucidate the role of genetic factors in arsenic metabolism, we investigated associations of genetic polymorphisms in the members of glutathione S-transferase (GST) superfamily with the arsenic concentrations in hair and urine, and urinary arsenic profile in residents in the Red River Delta, Vietnam. Genotyping was conducted for GST omega1 (GSTO1) Ala140Asp, Glu155del, Glu208Lys, Thr217Asn, and Ala236Val, GST omega2 (GSTO2) Asn142Asp, GST pi1 (GSTP1) Ile105Val, GST mu1 (GSTM1) wild/null, and GST theta1 (GSTT1) wild/null. There were no mutation alleles for GSTO1 Glu208Lys, Thr217Asn, and Ala236Val in this population. GSTO1 Glu155del hetero type showed higher urinary concentration of As(V) than the wild homo type. Higher percentage of DMA(V) in urine of GSTM1 wild type was observed compared with that of the null type. Strong correlations between GSTP1 Ile105Val and arsenic exposure level and profile were observed in this study. Especially, heterozygote of GSTP1 Ile105Val had a higher metabolic capacity from inorganic arsenic to monomethyl arsenic, while the opposite trend was observed for ability of metabolism from As(V) to As(III). Furthermore, other factors including sex, age, body mass index, arsenic level in drinking water, and genotypes of As (+3 oxidation state) methyltransferase (AS3MT) were also significantly co-associated with arsenic level and profile in the Vietnamese. To our knowledge, this is the first study indicating the associations of genetic factors of GST superfamily with arsenic metabolism in a Vietnamese population.

  20. Genetic polymorphisms in AS3MT and arsenic metabolism in residents of the Red River Delta, Vietnam

    SciTech Connect

    Agusa, Tetsuro; Iwata, Hisato Fujihara, Junko; Kunito, Takashi; Takeshita, Haruo; Minh, Tu Binh; Trang, Pham Thi Kim; Viet, Pham Hung; Tanabe, Shinsuke

    2009-04-15

    To elucidate the role of genetic factors in arsenic (As) metabolism, we studied associations of single nucleotide polymorphisms (SNPs) in As (+ 3 oxidation state) methyltransferase (AS3MT) with the As concentrations in hair and urine, and urinary As profile in residents in the Red River Delta, Vietnam. Concentrations of total As in groundwater were 0.7-502 {mu}g/l. Total As levels in groundwater drastically decreased by using sand filter, indicating that the filter could be effective to remove As from raw groundwater. Concentrations of inorganic As (IAs) in urine and total As in hair of males were higher than those of females. A significant positive correlation between monomethylarsonic acid (MMA)/IAs and age in females indicates that older females have higher methylation capacity from IAs to MMA. Body mass index negatively correlated with urinary As concentrations in males. Homozygote for SNPs 4602AA, 35991GG, and 37853GG, which showed strong linkage disequilibrium (LD), had higher percentage (%) of dimethylarsinic acid (DMA) in urine. SNPs 4740 and 12590 had strong LD and associated with urinary %DMA. Although SNPs 6144, 12390, 14215, and 35587 comprised LD cluster, homozygotes in SNPs 12390GG and 35587CC had lower DMA/MMA in urine, suggesting low methylation capacity from MMA to DMA in homo types for these SNPs. SNPs 5913 and 8973 correlated with %MMA and %DMA, respectively. Heterozygote for SNP 14458TC had higher MMA/IAs in urine than TT homozygote, indicating that the heterozygote may have stronger methylation ability of IAs. To our knowledge, this is the first study on the association of genetic factors with As metabolism in Vietnamese.

  1. Genetic polymorphisms in glutathione S-transferase (GST) superfamily and arsenic metabolism in residents of the Red River Delta, Vietnam

    SciTech Connect

    Agusa, Tetsuro; Iwata, Hisato; Fujihara, Junko; Kunito, Takashi; Takeshita, Haruo; Tu Binh Minh; Pham Thi Kim Trang; Pham Hung Viet; Tanabe, Shinsuke

    2010-02-01

    To elucidate the role of genetic factors in arsenic metabolism, we investigated associations of genetic polymorphisms in the members of glutathione S-transferase (GST) superfamily with the arsenic concentrations in hair and urine, and urinary arsenic profile in residents in the Red River Delta, Vietnam. Genotyping was conducted for GST omega1 (GSTO1) Ala140Asp, Glu155del, Glu208Lys, Thr217Asn, and Ala236Val, GST omega2 (GSTO2) Asn142Asp, GST pi1 (GSTP1) Ile105Val, GST mu1 (GSTM1) wild/null, and GST theta1 (GSTT1) wild/null. There were no mutation alleles for GSTO1 Glu208Lys, Thr217Asn, and Ala236Val in this population. GSTO1 Glu155del hetero type showed higher urinary concentration of As{sup V} than the wild homo type. Higher percentage of DMA{sup V} in urine of GSTM1 wild type was observed compared with that of the null type. Strong correlations between GSTP1 Ile105Val and arsenic exposure level and profile were observed in this study. Especially, heterozygote of GSTP1 Ile105Val had a higher metabolic capacity from inorganic arsenic to monomethyl arsenic, while the opposite trend was observed for ability of metabolism from As{sup V} to As{sup III}. Furthermore, other factors including sex, age, body mass index, arsenic level in drinking water, and genotypes of As (+ 3 oxidation state) methyltransferase (AS3MT) were also significantly co-associated with arsenic level and profile in the Vietnamese. To our knowledge, this is the first study indicating the associations of genetic factors of GST superfamily with arsenic metabolism in a Vietnamese population.

  2. Genesis of economic relevant fresh groundwater resources in Pleistocene/ Neogene aquifers in Nam Dinh (Red River Delta, Vietnam).

    NASA Astrophysics Data System (ADS)

    Wagner, F.; Ludwig, R. R.; Noell, U.; Hoang, H. V.; Pham, N. Q.; Larsen, F.; Lindenmaier, F.

    2012-04-01

    In the Southern Red River Delta (Nam Dinh Province, Vietnam), a local lens of low saline pore water of high quality has been identified in unconsolidated Pleistocene and Neogene aquifers, which are regionally known to contain brackish and saline pore waters. Since the 1990ies, ongoing overexploitation of the fresh groundwater results in decreasing GW heads up to 0.6 m/a and the development of a regional abstraction cone. The presented study focuses on distribution and genesis of fresh and saline pore waters and reflects the results in frame of the regional hydrogeological context. Observations of the geological structure and groundwater dynamics combined with hydrochemical and isotopic studies suggest adjacent Triassic hard rock aquifers as the major source for fresh Pleistocene and Neogene groundwater. Salinization status in the economically most relevant Pleistocene aquifer has been studied based on archive and new hydrochemical and geophysical data. Own hydrochemical field studies as well as laboratory measurements of the specific resistivity of dry sediment samples allow the translation of induction logging data from existing monitoring wells into vertical pore water salinity profiles. This approach suggests the regional occurrence of saline pore water in shallow Holocene sediments in the working area, as confirmed by pore water studies in Hoan et al. (2010). Interpretation of induction logging and stable isotope data suggest vertical diffusion of saline pore water in shallow Holocene sediments as a source for high saline pore water in deeper aquifers. Analytical diffusion modeling for a period of 3000 years confirms that vertical diffusion of Holocene paleo-sea water can explain saline pore water in Pleistocene and Neogene aquifers in a stagnant environment. The constant influx of fresh groundwater from adjacent Triassic hard rocks results in flushing of the primary Pleistocene and Neogene pore water and inhibits the infiltration of saline water from marine

  3. Two previously unknown Phytophthora species associated with brown rot of Pomelo (Citrus grandis) fruits in Vietnam

    PubMed Central

    Schena, Leonardo; Jung, Thomas; Evoli, Maria; Pane, Antonella; Van Hoa, Nguyen; Van Tri, Mai; Wright, Sandra; Ramstedt, Mauritz; Olsson, Christer; Faedda, Roberto; Magnano di San Lio, Gaetano

    2017-01-01

    Two distinct Phytophthora taxa were found to be associated with brown rot of pomelo (Citrus grandis), a new disease of this ancestral Citrus species, in the Vinh Long province, Mekong River Delta area, southern Vietnam. On the basis of morphological characters and using the ITS1-5.8S-ITS2 region of the rDNA and the cytochrome oxidase subunit 1 (COI) as barcode genes, one of the two taxa was provisionally named as Phytophthora sp. prodigiosa, being closely related to but distinct from P. insolita, a species in Phytophthora Clade 9, while the other one, was closely related to but distinct from the Clade 2 species P. meadii and was informally designated as Phytophthora sp. mekongensis. Isolates of P. sp. prodigiosa and P. sp. mekongensis were also obtained from necrotic fibrous roots of Volkamer lemon (C. volkameriana) rootstocks grafted with ‘King’ mandarin (Citrus nobilis) and from trees of pomelo, respectively, in other provinces of the Mekong River Delta, indicating a widespread occurrence of both Phytophthora species in this citrus-growing area. Koch’s postulates were fulfilled via pathogenicity tests on fruits of various Citrus species, including pomelo, grapefruit (Citrus x paradisi), sweet orange (Citrus x sinensis) and bergamot (Citrus x bergamia) as well as on the rootstock of 2-year-old trees of pomelo and sweet orange on ‘Carrizo’ citrange (C. sinensis ‘Washington Navel’ x Poncirus trifoliata). This is the first report of a Phytophthora species from Clade 2 other than P. citricola and P. citrophthora as causal agent of fruit brown rot of Citrus worldwide and the first report of P. insolita complex in Vietnam. Results indicate that likely Vietnam is still an unexplored reservoir of Phytophthora diversity. PMID:28208159

  4. Recent social and biogeophysical changes in the Ganges-Brahmaputra-Meghna, Mekong, and Amazon deltas as inputs into evolutionary policy-making.

    NASA Astrophysics Data System (ADS)

    de Araujo Barbosa, C. C.; Hossain, S.; Szabo, S.; Matthews, Z.; Heard, S.; Dearing, J.

    2014-12-01

    Policy-making in social-ecological systems increasingly looks to iterative, evolutionary approaches that can address the inherent complexity of interactions between human wellbeing, agricultural and aquacultural production, and ecosystem services. Here we show how an analysis of available time-series in delta regions over past decades can provide important insight into the social-ecological system dynamics that result from the complexity. The presentation summarises the recent changes for major elements of each social-ecological system, for example demography, economy, health, climate, food, and water. Time-series data from official statistics, monitoring programmes and sequential satellite imagery are analysed to define the range of trends, the presence of change points, slow and fast variables, and the significant drivers of change. For example, in the Bangladesh delta zone, increasing gross domestic product and per capita income levels since the 1980s mirror rising levels of food and inland fish production. In contrast, non-food ecosystem services such as water availability, water quality and land stability have deteriorated. As a result, poverty alleviation is associated with environmental degradation. Trends in indicators of human wellbeing and ecosystem services point to widespread non-stationary dynamics governed by slowly changing variables with increased probability of systemic threshold changes/tipping points in the near future. We conclude by examining how the findings could feed into new management tools, such as system dynamic models and assessments of safe operating spaces. Such tools have the potential to help create policies that deliver alternative and sustainable paths for land management while accommodating social and environmental change.

  5. Dealing with the safety paradox of delta-branches closure; a geomorphology study

    NASA Astrophysics Data System (ADS)

    Sloff, C.; Tromp, R.; Sieben, A.

    2013-12-01

    Closing off estuaries by dams is a conventional solution to reduce flood risks and salt intrusion in river deltas. However, if not all branches are closed, residual tidal currents develop or increase in connecting channels between the closed and open branches. These channels start to erode, causing bank instability and possible failure of levees. Hence, paradoxically, the intended increase in safety by this closure creates a new threat with increased flood risks. We illustrate this for existing channel erosion and dike stability problems in the Dutch Rhine River delta in the Netherlands, as well as for proposed future closure works in the Mekong River in Vietnam. Crucial for assessing and dealing with the erosion problems, is a proper prediction of flow conditions and of bed erodibility. The channels incise ancient deltaic deposits, consisting of diverse sections and layers of sand, clay and peat with diverse states of compaction. In the presented studies we show how we applied Delft3D to model the full delta, with all relevant dynamics and complex interactions between tidal flow and river discharges. For the Dutch situation, we simulated the long-term fate of the eroding interconnecting channels, applying a detailed description of subsurface heterogeneous erodibility (space and depth varying). Since these rivers are incising slowly in clay and peat beds covering highly-erodible sand layers, alternate sections occur of undersupplied ';fixed' beds, and of very deep scour holes. For the Vietnam case, we show how the location of a barrier and operation of gates, can be used to control both the salinity intrusion and channel erosion for the Mekong delta. Although the morphology studies for the Dutch delta with high-density data availability obviously justify a detailed Delft3D approach, it is shown that even in the Mekong delta with poor data quality, a coarse-grid large-scale Delft3D model can provide the answers necessary for planning the closure works and potential

  6. Enhancing Floodplain Management in the Lower Mekong River Basin Using Vegetation and Water Cycle Satellite Observations

    NASA Astrophysics Data System (ADS)

    Bolten, J. D.; Spruce, J.; Wilson, R.; Strauch, K.; Doyle, T.; Srinivan, R.; Lakshmi, V.; Gupta, M.

    2014-12-01

    The Lower Mekong River Basin shared by China, Burma, Laos, Thailand, Cambodia, and Vietnam, is considered the lifeblood of Southeast Asia. The Mekong Basin is subject to large hydrological fluctuations on a seasonal and inter-annual basis. The basin remains prone to severe annual floods that continue to cause widespread damage and endanger food security and the livelihood of the millions who dwell in the region. Also the placement of newly planned dams primarily for hydropower in the Lower Mekong Basin may cause damaging social, agriculture and fisheries impacts to the region where we may now likely be at a critical 'tipping point'. The primary goal of this project is to apply NASA and USGS products, tools, and information for improved flood and water management in the Lower Mekong River Basin to help characterize, understand, and predict future changes on the basin. Specifically, we are providing and helping transfer to the Mekong River Commission (MRC) and the member countries of Thailand, Cambodia, Lao, Vietnam, and Burma the enhanced Soil and Water Assessment Tool (SWAT) using remotely sensed surface, ground water, and root zone soil moisture along with improved Land Use and Land Cover (LULC) maps. In order to estimate the flood potential and constrain the SWAT Available Water Capacity model parameter over the region, we are assimilated GRACE Terrestrial Water Storage observations into the Catchment Land Surface Model. In addition, a Graphic Visualization Tool (GVT) as been developed to work in concert with the output of the SWAT model parameterized for the Mekong Basin as an adjunct tool of the MRC Decision Support Framework. The project requires a close coordination of the development and assessment of the enhanced MRC SWAT with the guidance of MRC resource managers and technical advisors. This presentation will evaluate the skill of the enhanced SWAT model using qualitative (i.e., MODIS change detection) and quantitative (e.g., streamflow) metrics over one

  7. Dilemmas in examining understanding of nature of science in Vietnam

    NASA Astrophysics Data System (ADS)

    Thao-Do, Thi Phuong; Yuenyong, Chokchai

    2015-12-01

    Scholars proved nature of science (NOS) has made certain contributions to science teaching and learning. Nonetheless, what, how and how much NOS should be integrated in the science curriculum of each country cannot be a benchmark, due to the influence of culture and society. Before employing NOS in a new context, it should be carefully studied. In assessing views of NOS in Vietnam, a developing country with Eastern culture where the NOS is not consider a compulsory learning outcome, there are several issues that researchers and educators should notice to develop an appropriate instrument that can clearly exhibit a NOS view of Vietnamese. They may include: time for the survey; length, content, type, and terms of the questionnaire; Vietnamese epistemology and philosophy; and some other Vietnamese social and cultural aspects. The most important reason for these considerations is that a Vietnamese view of NOS and NOS assessment possibly differs from the Western ideas due to the social and cultural impact. As a result, a Western assessment tool may become less effective in an Eastern context. The suggestions and implications in this study were derived from a prolonged investigation on Vietnamese science teacher educators and student teachers of School of Education, at Can Tho University, a State University in Mekong Delta region, Vietnam.

  8. DELTAE

    SciTech Connect

    Ward, W.C. ); Swift, G.W. )

    1993-11-01

    In thermoacoustic engines and refrigerators, and in many simple acoustic systems, a one dimensional wave equation determines the spatial dependence of the acoustic pressure and velocity. DELTAE numerically integrates such wave equations in the acoustic approximation, in gases or liquids, in user-defined geometries. Boundary conditions can include conventional acoustic boundary conditions of geometry and impedance, as well as temperature and thermal power in thermoacoustic systems. DELTAE can be used easily for apparatus ranging from simple duct networks and resonators to thermoacoustic engines refrigerators and combinations thereof. It can predict how a given apparatus will perform, or can allow the user to design an apparatus to achieve desired performance. DELTAE views systems as a series of segments; twenty segment types are supported. The purely acoustic segments include ducts and cones, and lumped impedances including compliances, series impedances, and endcaps. Electroacoustics tranducer segments can be defined using either frequency-independent coefficients or the conventional parameters of loudspeaker-style drivers: mass, spring constant, magnetic field strength, etc. Tranducers can be current driven, voltage driven, or connected to an electrical load impedance. Thermoacoustic segment geometries include parallel plates, circular and rectangular pores, and pin arrays. Side branches can be defined with fixed impedances, frequency-dependent radiation impedances, or as an auxiliary series of segments of any types. The user can select working fluids from among air, helium, neon, argon, hydrogen, deuterium, carbon dioxide, nitrogen, helium-argon mixtures, helium-xenon mixtures, liquid sodium, and eutectic sodium-potassium. Additional fluids and solids can be defined by the user.

  9. The Potential of Time Series Based Earth Observation for the Monitoring of Large River Deltas

    NASA Astrophysics Data System (ADS)

    Kuenzer, C.; Leinenkugel, P.; Huth, J.; Ottinger, M.; Renaud, F.; Foufoula-Georgiou, E.; Vo Khac, T.; Trinh Thi, L.; Dech, S.; Koch, P.; Le Tissier, M.

    2015-12-01

    Although river deltas only contribute 5% to the overall land surface, nearly six hundred million people live in these complex social-ecological environments, which combine a variety of appealing locational advantages. In many countries deltas provide the major national contribution to agricultural and industrial production. At the same time these already very dynamic environments are exposed to a variety of threats, including the disturbance and replacement of valuable ecosystems, increasing water, soil, and air pollution, human induced land subsidence, sea level rise, as well upstream developments impacting water and sediment supplies. A constant monitoring of delta systems is thus of utmost relevance for understanding past and current land surface change and anticipating possible future developments. We present the potential of Earth Observation based analyses and derived novel information products that can play a key role in this context. Along with the current trend of opening up numerous satellite data archives go increasing capabilities to explore big data. Whereas in past decades remote sensing data were analysed based on the spectral-reflectance-defined 'finger print' of individual surfaces, we mainly exploit the 'temporal fingerprints' of our land surface in novel pathways of data analyses at differing spatial-, and temporally-dense scales. Following our results on an Earth Observation based characterization of large deltas globally, we present in depth results from the Mekong Delta in Vietnam, the Yellow River Delta in China, the Niger Delta in Nigeria, as well as additional deltas, focussing on the assessment of river delta flood and inundation dynamics, river delta coastline dynamics, delta morphology dynamics including the quantification of erosion and accretion processes, river delta land use change and trends, as well as the monitoring of compliance to environmental regulations.

  10. Molecular Breeding to Improve Salt Tolerance of Rice (Oryza sativa L.) in the Red River Delta of Vietnam.

    PubMed

    Linh, Le Hung; Linh, Ta Hong; Xuan, Tran Dang; Ham, Le Huy; Ismail, Abdelbagi M; Khanh, Tran Dang

    2012-01-01

    Rice is a stable food in Vietnam and plays a key role in the economy of the country. However, the production and the cultivating areas are adversely affected from the threats of devastation caused by the rise of sea level. Using marker-assisted backcrossing (MABC) to develop a new salt tolerance rice cultivar is one of the feasible methods to cope with these devastating changes. To improve rice salt tolerance in BT7 cultivar, FL478 was used as a donor parent to introgress the Saltol QTL conferring salt tolerance into BT7. Three backcrosses were conducted and successfully transferred positive alleles of Saltol from FL478 into BT7. The plants numbers IL-30 and IL-32 in BC(3)F(1) population expected recurrent genome recovery of up to 99.2% and 100%, respectively. These selected lines that carried the Saltol alleles were screened in field for their agronomic traits. All improved lines had Saltol allele similar to the donor parent FL478, whereas their agronomic performances were the same as the original BT7. We show here the success of improving rice salt tolerance by MABC and the high efficiency of selection in early generations. In the present study, MABC has accelerated the development of superior qualities in the genetic background of BT7.

  11. Indel-II region deletion sizes in the white spot syndrome virus genome correlate with shrimp disease outbreaks in southern Vietnam.

    PubMed

    Hoa, Tran Thi Tuyet; Zwart, Mark P; Phuong, Nguyen T; Oanh, Dang T H; de Jong, Mart C M; Vlak, Just M

    2012-06-13

    Sequence comparisons of the genomes of white spot syndrome virus (WSSV) strains have identified regions containing variable-length insertions/deletions (i.e. indels). Indel-I and Indel-II, positioned between open reading frames (ORFs) 14/15 and 23/24, respectively, are the largest and the most variable. Here we examined the nature of these 2 indel regions in 313 WSSV-infected Penaeus monodon shrimp collected between 2006 and 2009 from 76 aquaculture ponds in the Mekong Delta region of Vietnam. In the Indel-I region, 2 WSSV genotypes with deletions of either 5950 or 6031 bp in length compared with that of a reference strain from Thailand (WSSV-TH-96-II) were detected. In the Indel-II region, 4 WSSV genotypes with deletions of 8539, 10970, 11049 or 11866 bp in length compared with that of a reference strain from Taiwan (WSSV-TW) were detected, and the 8539 and 10970 bp genotypes predominated. Indel-II variants with longer deletions were found to correlate statistically with WSSV-diseased shrimp originating from more intensive farming systems. Like Indel-I lengths, Indel-II lengths also varied based on the Mekong Delta province from which farmed shrimp were collected.

  12. International river basin development and climatic change: The Lower Mekong of Southeast Asia

    SciTech Connect

    Jacobs, J.W.

    1992-01-01

    The world's most important effort in international river basin planning has been carried out in the Lower Mekong Basin of Southeast Asia. Coordinated planning of water resource development in the basin has been the responsibility of the United Nations-sponsored Mekong Committee, established in 1957. Original member nations of the Committee were Cambodia, Laos, Thailand, and Vietnam. The Committee has made an impressive list of contributions to regional water development in spite of several constrains on its work program (e.g., Vietnam War, erratic international funding, differing opinions of member nations regarding development). An emerging problem which may greatly affect the Mekong Committee is regional climate change resulting from human-induced global warming. The study canvasses the potential roles the Mekong Committee might play in helping lower Mekong inhabitants adjust to climatic change. In doing so, the historical record of the Committee is reviewed in terms of their contributions in addressing climate-related problems, such as floods and salinity intrusion. The changing context in which the Committee has operated is an important part of the record, as it has both enabled and constrained Committee activities. The Committee's historical roles in promoting development suggest that their future roles in addressing climatic change will likely be in the areas of data gathering and dissemination, small-scale structural measures, and flood and low-flow forecasting. These sub-programs have been important to many Lower Basin inhabitants and are critical to sound river basin planning. In a broader sense, the Committee's ability to operate in the face of numerous disturbances suggests a high degree of institutional resiliency. This thesis argues that the committee's ability to withstand several shocks to its work program will allow it to better adjust to future changes, including climate change.

  13. Data sharing in international transboundary contexts: The Vietnamese perspective on data sharing in the Lower Mekong Basin

    NASA Astrophysics Data System (ADS)

    Thu, Hang Ngo; Wehn, Uta

    2016-05-01

    Transboundary data sharing is widely recognised as a necessary element in the successful handling of water-related climate change issues, as it is a means towards integrated water resources management (IWRM). However, in practice it is often a challenge to achieve it. The Mekong River Commission (MRC), an inter-governmental agency established by Cambodia, Lao PDR, Thailand and Vietnam, has adopted IWRM in its water strategy plan in order to properly manage the transboundary waters of the Mekong River. In this context, data sharing procedures were institutionalised and have been officially implemented by the four member countries since 2001. This paper uses a systematic approach to identify the extent of data sharing and the factors influencing the willingness of key individuals in the Vietnam National Mekong Committee and its Primary Custodians to share data. We find that the initial objectives of the Procedures for Data and Information Exchange and Sharing (PDIES) have not been fully achieved and, further, that Vietnam has much to gain and little to lose by engaging in data sharing in the MRC context. The primary motivation for data sharing stems from the desire to protect national benefits and to prevent upstream countries from overexploiting the shared water resources. However, data sharing is hindered by a lack of national regulations in the Vietnam context concerning data sharing between state agencies and outdated information management systems.

  14. Mekong River flow and hydrological extremes under climate change

    NASA Astrophysics Data System (ADS)

    Phi Hoang, Long; Lauri, Hannu; Kummu, Matti; Koponen, Jorma; van Vliet, Michelle T. H.; Supit, Iwan; Leemans, Rik; Kabat, Pavel; Ludwig, Fulco

    2016-07-01

    Climate change poses critical threats to water-related safety and sustainability in the Mekong River basin. Hydrological impact signals from earlier Coupled Model Intercomparison Project phase 3 (CMIP3)-based assessments, however, are highly uncertain and largely ignore hydrological extremes. This paper provides one of the first hydrological impact assessments using the CMIP5 climate projections. Furthermore, we model and analyse changes in river flow regimes and hydrological extremes (i.e. high-flow and low-flow conditions). In general, the Mekong's hydrological cycle intensifies under future climate change. The scenario's ensemble mean shows increases in both seasonal and annual river discharges (annual change between +5 and +16 %, depending on location). Despite the overall increasing trend, the individual scenarios show differences in the magnitude of discharge changes and, to a lesser extent, contrasting directional changes. The scenario's ensemble, however, shows reduced uncertainties in climate projection and hydrological impacts compared to earlier CMIP3-based assessments. We further found that extremely high-flow events increase in both magnitude and frequency. Extremely low flows, on the other hand, are projected to occur less often under climate change. Higher low flows can help reducing dry season water shortage and controlling salinization in the downstream Mekong Delta. However, higher and more frequent peak discharges will exacerbate flood risks in the basin. Climate-change-induced hydrological changes will have important implications for safety, economic development, and ecosystem dynamics and thus require special attention in climate change adaptation and water management.

  15. A fluvial and pluvial probabilistic flood hazard analysis for Can Tho city, Vietnam

    NASA Astrophysics Data System (ADS)

    Apel, Heiko; Martinez, Oriol; Thi Chinh, Do; Viet Dung, Nguyen

    2014-05-01

    Can Tho city is the largest city and the economic heart of the Mekong Delta, Vietnam. Due to its economic importance and envisaged development goals the city grew rapidly in population size and extend over the last two decades. Large parts of the city are located in flood prone areas, and also the central parts of the city recently experienced an increasing number of flood events, both of fluvial and pluvial nature. As the economic power and asset values are constantly increasing, this poses a considerable risk for the city. The the aim of this study is to perform a flood hazard analysis considering both fluvial and pluvial floods and to derive probabilistic flood hazard maps. This requires in a first step an understanding of the typical flood mechanisms. Fluvial floods are triggered by a coincidence of high water levels during the annual flood period in the Mekong Delta with high tidal levels, which cause in combination short term inundations in Can Tho. Pluvial floods are triggered by typical tropical convective rain storms during the monsoon season. These two flood pathways are essentially independent in its sources and can thus be treated in the hazard analysis accordingly. For the fluvial hazard analysis we propose a bivariate frequency analysis of the Mekong flood characteristics, the annual maximum flood discharge Q and the annual flood volume V at the upper boundary of the Mekong Delta, the gauging station Kratie. This defines probabilities of exceedance of different Q-V pairs, which are transferred into synthetic flood hydrographs. The synthetic hydrographs are routed through a quasi-2D hydrodynamic model of the entire Mekong Delta in order to provide boundary conditions for a detailed hazard mapping of Can Tho. This downscaling step is necessary, because the huge complexity of the river and channel network does not allow for a proper definition of boundary conditions for Can Tho city by gauge data alone. In addition the available gauge data around Can Tho

  16. Seasonal fluctuations of surface water levels in the Mekong River basin from satellite altimetry and other remote sensing data

    NASA Astrophysics Data System (ADS)

    Dominh, K.; Letoan, T.; Cazenave, A.; Mognard-Campbell, N.; Lhermitte, J.

    2004-05-01

    Ten years of satellite altimetry data from the Topex/Poseidon satellite have been analysed to construct water level time series and five years of satellite SPOT Vegetation imagery have been used to monitor the flood extent over the Mekong River basin. Areas overflown by T/P include the Tonle Sap Lake, seasonaly inundated areas and several branches of the hydrographic network of the Mekong delta. Very strong seasonal signal is reported over the Tonle Sap, amplitude reaching annually 5-8 meters peak to peak. Clear interannual signal is also visible. For example year 1999 corresponds to weak floods, contrasting with year 2000 during which strong flood is noticed. Southward, we also observe large seasonal fluctuations (2-3 m) over inundated floodplains, as identified using imagery data from the SPOT Vegetation instrument. Several water level time series have also been constructed at intersections of T/P tracks and waterways of the Mekong Delta. Depending on the location, quite different annual amplitudes are observed, the closer to the Mekong mouth, the smaller the signal. We interpret this observation as the effect of dams built over the Delta in the recent years/decades. We also analysed the interannual water level signal together with precipitations over the whole Mekong basin.

  17. Dams in the Mekong River Basin: Options for Improved Sediment and Fish Passage

    NASA Astrophysics Data System (ADS)

    Wild, T. B.; Loucks, D. P.

    2014-12-01

    The Mekong River and its tributaries comprise one of the most productive fish habitats in the world today. The economic value of the Mekong fishery in Lao PDR, Cambodia and Vietnam is among the highest in the world, providing income and food security to tens of millions of people. However, the construction of multiple dams in the basin will reduce sediment discharge, which will adversely impact nutrient transport and habitat quality and availability, and disrupt fish migration routes. Thus, of considerable interest is the identification of alternatives to the location, design and operation of planned hydropower dams that could improve sediment passage, enable migratory fish passage, and sustain fish production for local use. This paper describes the results of simulation studies designed to identify and evaluate such alternatives, as well as their potential impact on hydropower production. Dam sites in Cambodia and Lao PDR on tributaries and on the mainstream Mekong River will be discussed. Evaluations of sediment management techniques such as flushing, sluicing and bypassing will be discussed. This study is intended to inform decision makers in Cambodia, Lao PDR and Vietnam about potential alternatives to current plans as they prepare decisions regarding the development of over 100 hydropower dams throughout the basin.

  18. Malaria Modeling and Surveillance for the Greater Mekong Subregion

    NASA Technical Reports Server (NTRS)

    Kiang, Richard; Adimi, Farida; Soika, Valerii; Nigro, Joseph

    2005-01-01

    At 4,200 km, the Mekong River is the tenth longest river in the world. It directly and indirectly influences the lives of hundreds of millions of inhabitants in its basin. The riparian countries - Thailand, Myanmar, Cambodia, Laos, Vietnam, and a small part of China - form the Greater Mekong Subregion (GMS). This geographical region has the misfortune of being the world's epicenter of falciparum malaria, which is the most severe form of malaria caused by Plasmodium falciparum. Depending on the country, approximately 50 to 90% of all malaria cases are due to this species. In the Malaria Modeling and Surveillance Project, we have been developing techniques to enhance public health's decision capability for malaria risk assessments and controls. The main objectives are: 1) Identifying the potential breeding sites for major vector species; 2) Implementing a malaria transmission model to identify the key factors that sustain or intensify malaria transmission; and 3) Implementing a risk algorithm to predict the occurrence of malaria and its transmission intensity. The potential benefits are: 1) Increased warning time for public health organizations to respond to malaria outbreaks; 2) Optimized utilization of pesticide and chemoprophylaxis; 3) Reduced likelihood of pesticide and drug resistance; and 4) Reduced damage to environment. Environmental parameters important to malaria transmission include temperature, relative humidity, precipitation, and vegetation conditions. These parameters are extracted from NASA Earth science data sets. Hindcastings based on these environmental parameters have shown good agreement to epidemiological records.

  19. Mekong Basin Disease Surveillance (MBDS): A Trust-Based Network

    PubMed Central

    Phommasack, Bounlay; Jiraphongsa, Chuleeporn; Ko Oo, Moe; Bond, Katherine C.; Phaholyothin, Natalie; Suphanchaimat, Rapeepong; Ungchusak, Kumnuan; Macfarlane, Sarah B.

    2013-01-01

    The Mekong Basin Disease Surveillance (MBDS) network was formally established in 2001 through a Memorandum of Understanding signed by six Ministers of Health of the countries in the Greater Mekong sub-region: Cambodia, China (Yunnan and Guangxi), Lao PDR, Myanmar, Thailand and Vietnam. The main areas of focus of the network are to: i) improve cross-border infectious disease outbreak investigation and response by sharing surveillance data and best practices in disease recognition and reporting, and by jointly responding to outbreaks; ii) develop expertise in epidemiological surveillance across the countries; and iii) enhance communication between the countries. Comprised of senior health officials, epidemiologists, health practitioners, and other professionals, the MBDS has grown and matured over the years into an entity based on mutual trust that can be sustained into the future. Other regions have started emulating the network's pioneering work. In this paper, we describe the development of MBDS, the way in which it operates today, and some of its achievements. We present key challenges the network has faced and lessons its members have learned about how to develop sufficient trust for health and other professionals to alert each other to disease threats across national borders and thereby more effectively combat these threats. PMID:23362411

  20. Vietnam Revisited.

    ERIC Educational Resources Information Center

    Esper, George

    1990-01-01

    Reflections of an Associated Press special correspondent on a return visit to Vietnam 15 years after the war. Discusses the social and economic impact of the war on Vietnam. Examines the plight of the Vietnamese who served in the U.S. military, discussing the problems of Amerasians. Recounts the efforts of U.S. veterans to rebuild Vietnam. (RW)

  1. Detection and Characterization of Clade 1 Reassortant H5N1 Viruses Isolated from Human Cases in Vietnam during 2013.

    PubMed

    Thor, Sharmi W; Nguyen, Hieu; Balish, Amanda; Hoang, Anh Nguyen; Gustin, Kortney M; Nhung, Pham Thi; Jones, Joyce; Thu, Ngoc Nguyen; Davis, William; Ngoc, Thao Nguyen Thi; Jang, Yunho; Sleeman, Katrina; Villanueva, Julie; Kile, James; Gubareva, Larisa V; Lindstrom, Stephen; Tumpey, Terrence M; Davis, C Todd; Long, Nguyen Thanh

    2015-01-01

    Highly pathogenic avian influenza (HPAI) H5N1 is endemic in Vietnamese poultry and has caused sporadic human infection in Vietnam since 2003. Human infections with HPAI H5N1 are of concern due to a high mortality rate and the potential for the emergence of pandemic viruses with sustained human-to-human transmission. Viruses isolated from humans in southern Vietnam have been classified as clade 1 with a single genome constellation (VN3) since their earliest detection in 2003. This is consistent with detection of this clade/genotype in poultry viruses endemic to the Mekong River Delta and surrounding regions. Comparison of H5N1 viruses detected in humans from southern Vietnamese provinces during 2012 and 2013 revealed the emergence of a 2013 reassortant virus with clade 1.1.2 hemagglutinin (HA) and neuraminidase (NA) surface protein genes but internal genes derived from clade 2.3.2.1a viruses (A/Hubei/1/2010-like; VN12). Closer analysis revealed mutations in multiple genes of this novel genotype (referred to as VN49) previously associated with increased virulence in animal models and other markers of adaptation to mammalian hosts. Despite the changes identified between the 2012 and 2013 genotypes analyzed, their virulence in a ferret model was similar. Antigenically, the 2013 viruses were less cross-reactive with ferret antiserum produced to the clade 1 progenitor virus, A/Vietnam/1203/2004, but reacted with antiserum produced against a new clade 1.1.2 WHO candidate vaccine virus (A/Cambodia/W0526301/2012) with comparable hemagglutination inhibition titers as the homologous antigen. Together, these results indicate changes to both surface and internal protein genes of H5N1 viruses circulating in southern Vietnam compared to 2012 and earlier viruses.

  2. Detection and Characterization of Clade 1 Reassortant H5N1 Viruses Isolated from Human Cases in Vietnam during 2013

    PubMed Central

    Balish, Amanda; Hoang, Anh Nguyen; Gustin, Kortney M.; Nhung, Pham Thi; Jones, Joyce; Thu, Ngoc Nguyen; Davis, William; Ngoc, Thao Nguyen Thi; Jang, Yunho; Sleeman, Katrina; Villanueva, Julie; Kile, James; Gubareva, Larisa V.; Lindstrom, Stephen; Tumpey, Terrence M.; Davis, C. Todd; Long, Nguyen Thanh

    2015-01-01

    Highly pathogenic avian influenza (HPAI) H5N1 is endemic in Vietnamese poultry and has caused sporadic human infection in Vietnam since 2003. Human infections with HPAI H5N1 are of concern due to a high mortality rate and the potential for the emergence of pandemic viruses with sustained human-to-human transmission. Viruses isolated from humans in southern Vietnam have been classified as clade 1 with a single genome constellation (VN3) since their earliest detection in 2003. This is consistent with detection of this clade/genotype in poultry viruses endemic to the Mekong River Delta and surrounding regions. Comparison of H5N1 viruses detected in humans from southern Vietnamese provinces during 2012 and 2013 revealed the emergence of a 2013 reassortant virus with clade 1.1.2 hemagglutinin (HA) and neuraminidase (NA) surface protein genes but internal genes derived from clade 2.3.2.1a viruses (A/Hubei/1/2010-like; VN12). Closer analysis revealed mutations in multiple genes of this novel genotype (referred to as VN49) previously associated with increased virulence in animal models and other markers of adaptation to mammalian hosts. Despite the changes identified between the 2012 and 2013 genotypes analyzed, their virulence in a ferret model was similar. Antigenically, the 2013 viruses were less cross-reactive with ferret antiserum produced to the clade 1 progenitor virus, A/Vietnam/1203/2004, but reacted with antiserum produced against a new clade 1.1.2 WHO candidate vaccine virus (A/Cambodia/W0526301/2012) with comparable hemagglutination inhibition titers as the homologous antigen. Together, these results indicate changes to both surface and internal protein genes of H5N1 viruses circulating in southern Vietnam compared to 2012 and earlier viruses. PMID:26244768

  3. Nationwide investigation of the pyrethroid susceptibility of mosquito larvae collected from used tires in Vietnam.

    PubMed

    Kawada, Hitoshi; Higa, Yukiko; Nguyen, Yen T; Tran, Son H; Nguyen, Hoa T; Takagi, Masahiro

    2009-01-01

    Pyrethroid resistance is envisioned to be a major problem for the vector control program since, at present, there are no suitable chemical substitutes for pyrethroids. Cross-resistance to knockdown agents, which are mainly used in mosquito coils and related products as spatial repellents, is the most serious concern. Since cross-resistance is a global phenomenon, we have started to monitor the distribution of mosquito resistance to pyrethroids. The first pilot study was carried out in Vietnam. We periodically drove along the national road from the north end to the Mekong Delta in Vietnam and collected mosquito larvae from used tires. Simplified susceptibility tests were performed using the fourth instar larvae of Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus. Compared with the other species, Ae. aegypti demonstrated the most prominent reduction in susceptibility. For Ae. aegypti, significant increases in the susceptibility indices with a decrease in the latitude of collection points were observed, indicating that the susceptibility of Ae. aegypti against d-allethrin was lower in the southern part, including mountainous areas, as compared to that in the northern part of Vietnam. There was a significant correlation between the susceptibility indices in Ae. aegypti and the sum of annual pyrethroid use for malaria control (1998-2002). This might explain that the use of pyrethroids as residual treatment inside houses and pyrethroid-impregnated bed nets for malaria control is attributable to low pyrethroid susceptibility in Ae. aegypti. Such insecticide treatment appeared to have been intensively administered in the interior and along the periphery of human habitation areas where, incidentally, the breeding and resting sites of Ae. aegypti are located. This might account for the strong selection pressure toward Ae. aegypti and not Ae. albopictus.

  4. Household trends in access to improved water sources and sanitation facilities in Vietnam and associated factors: findings from the Multiple Indicator Cluster Surveys, 2000-2011.

    PubMed

    Tuyet-Hanh, Tran Thi; Lee, Jong-Koo; Oh, Juhwan; Van Minh, Hoang; Ou Lee, Chul; Hoan, Le Thi; Nam, You-Seon; Long, Tran Khanh

    2016-01-01

    Background Despite progress made by the Millennium Development Goal (MDG) number 7.C, Vietnam still faces challenges with regard to the provision of access to safe drinking water and basic sanitation. Objective This paper describes household trends in access to improved water sources and sanitation facilities separately, and analyses factors associated with access to improved water sources and sanitation facilities in combination. Design Secondary data from the Vietnam Multiple Indicator Cluster Survey in 2000, 2006, and 2011 were analyzed. Descriptive statistics and tests of significance describe trends over time in access to water and sanitation by location, demographic and socio-economic factors. Binary logistic regressions (2000, 2006, and 2011) describe associations between access to water and sanitation, and geographic, demographic, and socio-economic factors. Results There have been some outstanding developments in access to improved water sources and sanitation facilities from 2000 to 2011. In 2011, the proportion of households with access to improved water sources and sanitation facilities reached 90% and 77%, respectively, meeting the 2015 MDG targets for safe drinking water and basic sanitation set at 88% and 75%, respectively. However, despite these achievements, in 2011, only 74% of households overall had access to combined improved drinking water and sanitation facilities. There were also stark differences between regions. In 2011, only 47% of households had access to both improved water and sanitation facilities in the Mekong River Delta compared with 94% in the Red River Delta. In 2011, households in urban compared to rural areas were more than twice as likely (odds ratio [OR]: 2.2; 95% confidence interval [CI]: 1.9-2.5) to have access to improved water and sanitation facilities in combination, and households in the highest compared with the lowest wealth quintile were over 40 times more likely (OR: 42.3; 95% CI: 29.8-60.0). Conclusions More efforts

  5. Assessment of persistent organic pollutants in sediments from Lower Mekong River Basin.

    PubMed

    Sudaryanto, Agus; Isobe, Tomohiko; Takahashi, Shin; Tanabe, Shinsuke

    2011-01-01

    Organochlorine compounds (OCs) in sediments collected from various locations in Lower Mekong River Basin (MRB) in Laos and Thailand were examined to elucidate their occurrence, distribution and potential ecological risk. Concentration of PCBs and DDTs were higher than other OCs, ranging from 0.18 to 310μgkg(-1) dry wt. and from 0.027 to 52μgkg(-1) dry wt., respectively, whereas CHLs, HCHs and HCB were 1-3 orders of magnitude lower. Geographical distribution indicates that levels of PCBs, DDTs and CHLs in the Vientiane canal were significantly higher than those in mainstream of Mekong River, Phong River and its surrounding areas, indicating significant sources of these compounds in urbanized areas. Comparison with other parts of MRB indicates that PCBs were higher in Laos, whereas DDTs were more prevalent in Mekong Delta, indicating location specific contaminations of these compounds in MRB. The ratios of DDTs composition indicate possible difference in the historical input of DDT among locations in and around Mekong River. Hazard assessment of PCBs and DDTs indicate possible toxic potential particularly in areas close to point sources such as intensive human activities and agricultural areas which highlight the need for further study.

  6. Sharing positive experiences in making changes in work and life in a local district in Vietnam.

    PubMed

    Kawakami, T; Khai, T T

    1997-12-01

    A series of research and training programmes were undertaken in a rural district in the Mekong Delta area in Vietnam so as to facilitate positive changes in the work and life under the initiatives of the local people. As in other parts of the area, it was amid rapid changes in life-style under the shift toward a market economy. Field research relying on direct observation methods were carried out in various rice field jobs and local small enterprises for understanding the improvement potentials in the work and lives of the local people. To strengthen the local improvement initiatives, participatory training programmes were developed and practiced. In the training programmes, joint walk-through observations using an action checklist were stressed. The results were discussed in small groups and meetings. Interactive communications between the local people, while visiting their own houses and workplaces, took place. Based on these field research results, various positive changes were successfully implemented. They included a wide range of improvements such as more efficient work methods, safer use of technologies, hygienic housing conditions, and improved household plans. Our experiences demonstrated that practical approaches relying on local initiatives could facilitate the implementation of positive changes in the local socio-cultural settings.

  7. Poverty, economic growth, deprivation, and water: the cases of Cambodia and Vietnam.

    PubMed

    Varis, Olli

    2008-05-01

    Poverty reduction decorates all development agendas, but the complexity of the poverty issue is too often hidden behind simplistic indicators and development goals. Here, a closer look is taken at the concepts of "deprivation" and "vulnerability" as outcomes of poverty. Deprivation leads typically to social exclusion and marginalization; such groups are particularly weak in getting themselves out of poverty by "self-help," and economic growth does not trickle down to these people. When looking at the connections between poverty reduction and economic growth, special emphasis should be put on the differences between modern and more traditional sectors: development of the modern sector should not marginalize and exclude those dependent on more traditional livelihoods. Two case studies--The Tonle Sap area, Cambodia, and the Mekong Delta, Vietnam--reveal that investment in education, empowerment of small-scale entrepreneurship and other means of microeconomic environment, along with good governance, infrastructure, and income distribution can ensure that economic growth includes the poorer echelons of society.

  8. Quality of Antimicrobial Products Used in Striped Catfish (Pangasianodon hypophthalmus) Aquaculture in Vietnam.

    PubMed

    Phu, Tran Minh; Phuong, Nguyen Thanh; Scippo, Marie-Louise; Dalsgaard, Anders

    2015-01-01

    Antimicrobial usage is common in Asian aquaculture. This study aimed to determine the quality of antimicrobial products used by Vietnamese striped catfish (Pangasianodon hypophthalmus) farmers. Twenty one antimicrobial products (11 products contained a single antimicrobial and 10 products contained a mixture of two different antimicrobials) commonly used by catfish farmers were obtained from so-called chemical shops located in the Mekong Delta, Vietnam. Ultra High Performance Liquid Chromatography Mass Spectrometry was used to analyze concentration of sulfonamides, trimethoprim, amoxicillin, cefalexin and ciprofloxacin whereas concentrations of florfenicol and doxycycline were analyzed by High Performance Liquid Chromatography with UV detection. Results revealed that only 4/11 products with a single antimicrobial and 2/10 products with a mixture of antimicrobials contained active substances within ±10% of the concentration declared on the product label. Two products with antimicrobial mixtures did not contain any of the declared antimicrobials. Comparing two batches, analysis of 11 products revealed that only one product contained a concentration of active compound that varied with less than 10% in both batches. Several product labels provided inadequate information on how to calculate therapeutic dosage and further stated withdrawal time despite lack of pharmacokinetic data on the antimicrobials in catfish. There is an urgent need to strengthen approval procedures and in particular regularly to monitor the quality of antimicrobials used in Vietnamese aquaculture.

  9. Quality of Antimicrobial Products Used in Striped Catfish (Pangasianodon hypophthalmus) Aquaculture in Vietnam

    PubMed Central

    Phu, Tran Minh; Phuong, Nguyen Thanh; Scippo, Marie-Louise; Dalsgaard, Anders

    2015-01-01

    Antimicrobial usage is common in Asian aquaculture. This study aimed to determine the quality of antimicrobial products used by Vietnamese striped catfish (Pangasianodon hypophthalmus) farmers. Twenty one antimicrobial products (11 products contained a single antimicrobial and 10 products contained a mixture of two different antimicrobials) commonly used by catfish farmers were obtained from so-called chemical shops located in the Mekong Delta, Vietnam. Ultra High Performance Liquid Chromatography Mass Spectrometry was used to analyze concentration of sulfonamides, trimethoprim, amoxicillin, cefalexin and ciprofloxacin whereas concentrations of florfenicol and doxycycline were analyzed by High Performance Liquid Chromatography with UV detection. Results revealed that only 4/11 products with a single antimicrobial and 2/10 products with a mixture of antimicrobials contained active substances within ±10% of the concentration declared on the product label. Two products with antimicrobial mixtures did not contain any of the declared antimicrobials. Comparing two batches, analysis of 11 products revealed that only one product contained a concentration of active compound that varied with less than 10% in both batches. Several product labels provided inadequate information on how to calculate therapeutic dosage and further stated withdrawal time despite lack of pharmacokinetic data on the antimicrobials in catfish. There is an urgent need to strengthen approval procedures and in particular regularly to monitor the quality of antimicrobials used in Vietnamese aquaculture. PMID:25897517

  10. Historical impact of water infrastructure on water levels of the Mekong River and the Tonle Sap system

    NASA Astrophysics Data System (ADS)

    Cochrane, T. A.; Arias, M. E.; Piman, T.

    2014-11-01

    rates respectively at Prek Kdam provides evidence of a diminished Tonle Sap flood pulse in the post-1991 period. Given the observed water level alterations from 1991 to 2010 as a result of water infrastructure development, we can extrapolate that future development in the mainstream and the key transboundary Srepok, Sesan, and Sekong sub-basins will have an even greater effect on the Tonle Sap flood regime, the lower Mekong floodplain, and the delta.

  11. Historical impact of water infrastructure on water levels of the Mekong River and the Tonle Sap System

    NASA Astrophysics Data System (ADS)

    Cochrane, T. A.; Arias, M. E.; Piman, T.

    2014-04-01

    Kdam provides evidence of a diminished Tonle Sap flood pulse in the post-1991 period. Given the observed water level alterations from 1991 to 2010 as a result of water infrastructure development, we can extrapolate that future development in the mainstream and the key transboundary Srepok, Sesan and Sekong subbasins will have an even greater effect on the Tonle Sap flood regime, the lower Mekong floodplain, and the delta.

  12. Linking monsoonal hydrology and sediment fluxes on the Lower Mekong River

    NASA Astrophysics Data System (ADS)

    Hackney, C. R.; Darby, S. E.; Aalto, R. E.; Best, J.; Leyland, J.; Nicholas, A. P.; Parsons, D. R.

    2013-12-01

    The Mekong is one of the world's great rivers and transports considerable volumes of water, sediment and associated nutrients during its monsoonal flood pulse. These sediments and nutrients exert a first order control on the sustainability of the Mekong's great delta and on the livelihoods of the people that live there. Yet, similar to many other of the world's large rivers, accurate measurements of the Mekong's sediment load are sporadic and subject to large errors, such that the available historical record is extremely limited. This presents a considerable challenge to those interested in evaluating how recent and future hydrological changes associated with environmental change (including climate change and the effects of major anthropogenic interventions such as damming) has affected sediment fluxes in the past and how they may alter in the future. A particular problem associated with making direct measurements of sediment loads on large rivers in developing countries is that monitoring programmes are both logistically challenging and resource constrained. Traditional methods frequently rely on the use of depth-integrated samplers that are time consuming to deploy, limiting data collection to a few point measurements. Furthermore, on big rivers the large flow depths involved can introduce uncertainties into the depth-integrating process. Since the mid 2000's a number of the national monitoring agencies on the Mekong River have begun to adopt Acoustic Doppler Current Profiling (ADCP) as their routine means of making hydrological measurements. However, these ADCP devices can also be used to estimate sediment loads by means of the acoustic backscatter returned from suspended particulates within the water column. Importantly, these backscatter data have been recorded during the recent measurement period, but they have not yet been systematically analysed. In a recent fieldwork campaign undertaken as part of the NERC funded STELAR-S2S project (www.stelar-s2s.org) we

  13. Vietnam Land Policy - Adjusting to Globalization

    DTIC Science & Technology

    2013-11-01

    Conflicts over Land in Vietnam’s Red River Delta," Journal of Southeast Asian Studies, (2007): 317, accessed 6 September 2013, JSTOR . 5...Responsibility and No Rice,”: The Rise and Fall of Agricultural Collectivization in Vietnam,” Agricultural History: vol 82, no. 1, (2008), 54, JSTOR . 18...Performance and Communist Legitimacy,” World Politics, vol. 38 no. 3, (1986): 463, accessed 22 October 2013, JSTOR . 32 Ibid., 463. 33 Elliott

  14. Prevalence of Waterpipe Tobacco Smoking Among Population Aged 15 Years or Older, Vietnam, 2010

    PubMed Central

    Van Minh, Hoang; Giang, Kim Bao; Nga, Pham Thi Quynh; Hai, Phan Thi; Minh, Nguyen Thac; Hsia, Jason

    2013-01-01

    Introduction The prevalence of waterpipe tobacco smoking is increasing globally and is associated with adverse outcomes requiring tobacco control interventions. We estimated the prevalence of waterpipe tobacco use among adult populations in Vietnam in 2010 and examined its association with sociodemographic factors. Methods We used data from the Global Adult Tobacco Survey (GATS) conducted in Vietnam in 2010. GATS surveyed a national representative sample of adults aged 15 years or older from 11,142 households by using a 2-phase sampling design analogous to a 3-stage stratified cluster sampling. Descriptive statistical analyses and multivariate logistic regression modeling were conducted. Results A total of 6.4% of Vietnamese aged 15 years or older (representing about 4.1 million adult waterpipe smokers) reported current waterpipe tobacco smoking. The prevalence of waterpipe tobacco smoking was significantly higher among men than women (13% vs 0.1%). Area of residence (rural or urban), age group, asset-based wealth quintile, and geographic region of residence were significantly associated with waterpipe tobacco smoking among men. The significant correlates of current waterpipe tobacco smoking among men were lower education levels, being middle-aged (45–54 years), lower asset-based wealth levels, living in rural areas, not living in the South East and the Mekong River Delta geographic regions, and the belief that smoking does not causes diseases. Conclusion Rural dwellers who are poor should be targeted in tobacco control programs. Further studies are needed that examine perceptions of the adverse health effects and the cultural factors of waterpipe tobacco smoking. PMID:23597395

  15. Water volume change in the lower Mekong from satellite altimetry and imagery data

    NASA Astrophysics Data System (ADS)

    Frappart, F.; Minh, K. Do; L'Hermitte, J.; Cazenave, A.; Ramillien, G.; Le Toan, T.; Mognard-Campbell, N.

    2006-11-01

    We have analysed satellite altimetry data from the ERS-2, ENVISAT and Topex/Poseidon satellites to construct water level time-series over a 8 yr period (from 1996 April to 2004 April) over the lower Mekong river basin. The study area includes the Tonle Sap Lake, seasonally inundated areas and several branches of the hydrographic network of the Mekong delta. We found a very strong seasonal signal over the main river north of 13°N, the Tonle Sap Lake and Tonle Sap river, with amplitudes reaching 8-10 m annually. We also found a clear interannual signal in altimetry-derived water level time-series. For example, year 1999 had weak floods (around 6 m amplitude), contrasting with year 2000 during which strong flood was noticed (around 10 m amplitude). Southwards, we also observed large seasonal fluctuations (2-3 m) over inundated floodplains, as identified using satellite imagery data from the SPOT-4 Vegetation instrument. Depending on the location, quite different annual amplitudes were observed, the closer to the Mekong mouth, the smaller the signal (less than 0.5 m seasonal amplitude). Using Normalized Difference Vegetation Index (NDVI) data from the Vegetation instrument, we studied the seasonal extent of flood plains in the delta. Then combining the areal extent of floods with water levels estimated from the ERS-2/ENVISAT data, we computed maps of monthly surface water volume change over six successive years (1998-2003), the period of availability of the NDVI data. Averaged over the lower Mekong basin, this surface water volume change was then compared to the total (i.e. surface plus underground) water volume change inferred from the GRACE satellite. They exhibit in-phase fluctuations.

  16. Use of black carp (Mylopharyngodon piceus) in biological control of intermediate host snails of fish-borne zoonotic trematodes in nursery ponds in the Red River Delta, Vietnam

    PubMed Central

    2013-01-01

    Background The risks of fish-borne zoonotic trematodes (FZT) to human health constitute an important problem in Vietnam. The infection of humans with these trematodes, such as small liver trematodes (Clonorchis sinensis and Opisthorchis viverrini), intestinal trematodes (Heterophyidae) and others is often thought to be linked to fish culture in areas where the habit of eating raw fish is common. Juvenile fish produced in nurseries are often heavily infected with FZT and since fishes are sold to aquaculture facilities for growth, control of FZT in these fishes should be given priority. Controlling the first intermediate host (i.e., freshwater gastropods), would be an attractive approach, if feasible. The black carp, Mylopharyngodon piceus, is a well-known predator of freshwater snails and is already used successfully for biological control of snails in various parts of the world including Vietnam. Here we report the first trials using it for biological control of intermediate host snails in nursery ponds stocked with 1-week old fry (10–12 mm in length) of Indian carp, Labeo rohita. Methods Semi-field and field experiments were set up to test the effect of black carp on snail populations. In the semi-field experiment a known quantity of snails was initially introduced into a pond which was subsequently stocked with black carp. In the field trial in nursery ponds, density of snails was estimated prior to a nursing cycle and at the end of the cycle (after 9 weeks). Results The results showed that black carp affect the density of snail populations in both semi-field and field conditions. The standing crop of snails in nursery ponds, however, was too high for 2 specimens to greatly reduce snail density within the relatively short nursing cycle. Conclusions We conclude that the black carp can be used in nursery ponds in Northern Vietnam for snail control. Juvenile black carp weighing 100 - 200g should be used because this size primarily prey on intermediate hosts of FZT

  17. Long-term trend of climate variables in the upper Dong Nai river basin in Vietnam

    NASA Astrophysics Data System (ADS)

    Truong, Nguyen Cung Que; Nguyen, Hong Quan; Kondoh, Akihiko

    2015-04-01

    Dong Nai river and Mekong delta downstream are located in and supplied the major water resources to the whole Southern of Vietnam. In the state of continuous changes in water resources due to climate changes, there are several controversy about the potential impact of sediment transport and river flows downstream due to either the cascade hydroelectric power plant system or dam construction in the upper of Mekong delta. Therefore, management and planning for efficient use of Dong Nai river water resource is very important. Furthermore, that it is necessary to consider the hydrological regime change by the effects of climate variable. On the other hand, solving the problems of water shortage in the dry season and flood control in rainy season are also important for issues of water management at Dong Nai river basin. In this study we evaluated changes in two main factors of the water balance equation (both rainfall and evapotranspiration) to assess long-term change in the hydrological regime in the upper area of Dong Nai river basin. This key theme was divided into the following two sub-goals. The first goal was to analyze long term spatial and temporal rainfall trends. The second goal was to analyze the long-term trend of meteorological factors determining evapotranspiration such as air temperature, wind speed, solar radiation and sunshine duration. The results were used to assess their impact to evapotranspiration. The meteorological and hydrological data of the basin for the last 20 years (from 1993 to 2012) were analyzed based on the Empirical Mode Decomposition (EMD) method. The EMD method has been pioneered by Huang et al. (1998) for adaptively representing nonstationary time-series data as sum of zero-mean amplitude modulation-frequency modulation (AM-FM) components by iteratively conducting the sifting process. These components called Intrinsic Mode Functions (IMFs) allow the calculation of a meaningful multi-component instantaneous frequency. The results

  18. Managing Mekong Mud and its Impact on Fish, Hydropower and People

    NASA Astrophysics Data System (ADS)

    Wild, T. B.; Loucks, D. P.

    2013-12-01

    The Lancang/Mekong River flows from the Tibetan Plateau through the Upper Mekong Basin in China (where it is called the Lancang Jiang) to the Lower Mekong Basin (LMB) in Myanmar, Laos, Thailand, Cambodia, and Vietnam, before discharging into the South China Sea. The river has remained largely unaltered for much of its history, but today hydropower reservoirs are being designed and developed at a rapid pace. Some 60 million people living in the basin have depended on the basin's ecosystems to produce much of their food and income. The health and productivity of the ecosystems are dependent upon the river's natural flow and sediment regimes, both of which could be significantly altered by the rapid construction of dams. This presentation focuses on the potential impacts of dam development and alternative sediment management options, where feasible, including flushing, sluicing, bypassing, and density current venting. We evaluate whether these techniques can improve reservoir sediment outflows without damaging the environmental system we are attempting to preserve. We also evaluate the accompanying losses in hydropower production necessary to achieve the improved sediment passage. This study focuses on dams in China, Cambodia, Laos and Vietnam, both on the mainstream Mekong River and on its tributaries. A sediment simulation model was developed specifically to conduct these evaluations. This model implements a daily time-step mass-balance simulation of flow and sediment to predict the spatial and temporal accumulation, depletion, and distribution of sediment in river reaches and in reservoirs under different flow and sediment management policies. Results of simulations suggest that more benign (with regard to sediment) alternatives to the currently proposed locations and designs of dams exist and should be considered. While sediment management alternatives have the potential to increase sediment loads discharged downstream, careful attention must be paid to the

  19. Induction of Antimicrobial Resistance in Escherichia coli and Non-Typhoidal Salmonella Strains after Adaptation to Disinfectant Commonly Used on Farms in Vietnam

    PubMed Central

    Nhung, Nguyen T.; Thuy, Cao T.; Trung, Nguyen V.; Campbell, James; Baker, Stephen; Thwaites, Guy; Hoa, Ngo T.; Carrique-Mas, Juan

    2015-01-01

    In Vietnam, commercial disinfectants containing quaternary ammonium compounds (QACs) are commonly used in pig and poultry farms to maintain hygiene during production. We hypothesized that sustained exposure to sub-bactericidal concentrations of QAC-based disinfectants may result in increased levels of antimicrobial resistance (AMR) among Enterobacteriacea due to the increase of efflux pump expression. To test this hypothesis we exposed six antimicrobial-susceptible Escherichia coli (E. coli) and six antimicrobial-susceptible non-typhoidal Salmonella (NTS) isolates to increasing concentrations of a commonly used commercial disinfectant containing a mix of benzalkonium chloride and glutaraldehyde. Over the 12-day experiment, strains exhibited a significant change in their minimum inhibitory concentration (MIC) of the disinfectant product (mean increase of 31% (SD ± 40)) (p = 0.02, paired Wilcoxon test). Increases in MIC for the disinfectant product were strongly correlated with increases in MIC (or decreases in inhibition zone) for all antimicrobials (Pearson’s correlation coefficient 0.71–0.83, all p < 0.01). The greatest increases in MIC (or decreases in inhibition zone) were observed for ampicillin, tetracycline, ciprofloxacin, and chloramphenicol, and the smallest for gentamicin, trimethoprim/sulphamethoxazole. The treatment of 155 representative E. coli isolates from farmed and wild animals in the Mekong Delta (Vietnam) with phenyl-arginine beta-naphthylamide (PAβN), a generic efflux pump inhibitor, resulted in reductions in the prevalence of AMR ranging from 0.7% to 3.3% in these organisms, indicating a small contribution of efflux pumps on the observed prevalence of AMR on farms. These results suggest that the mass usage of commercial disinfectants, many of which contain QACs, is potentially a contributing factor on the generation and maintenance of AMR in animal production in Vietnam. PMID:27025637

  20. Induction of Antimicrobial Resistance in Escherichia coli and Non-Typhoidal Salmonella Strains after Adaptation to Disinfectant Commonly Used on Farms in Vietnam.

    PubMed

    Nhung, Nguyen T; Thuy, Cao T; Trung, Nguyen V; Campbell, James; Baker, Stephen; Thwaites, Guy; Hoa, Ngo T; Carrique-Mas, Juan

    2015-10-30

    In Vietnam, commercial disinfectants containing quaternary ammonium compounds (QACs) are commonly used in pig and poultry farms to maintain hygiene during production. We hypothesized that sustained exposure to sub-bactericidal concentrations of QAC-based disinfectants may result in increased levels of antimicrobial resistance (AMR) among Enterobacteriacea due to the increase of efflux pump expression. To test this hypothesis we exposed six antimicrobial-susceptible Escherichia coli (E. coli) and six antimicrobial-susceptible non-typhoidal Salmonella (NTS) isolates to increasing concentrations of a commonly used commercial disinfectant containing a mix of benzalkonium chloride and glutaraldehyde. Over the 12-day experiment, strains exhibited a significant change in their minimum inhibitory concentration (MIC) of the disinfectant product (mean increase of 31% (SD ± 40)) (p = 0.02, paired Wilcoxon test). Increases in MIC for the disinfectant product were strongly correlated with increases in MIC (or decreases in inhibition zone) for all antimicrobials (Pearson's correlation coefficient 0.71-0.83, all p < 0.01). The greatest increases in MIC (or decreases in inhibition zone) were observed for ampicillin, tetracycline, ciprofloxacin, and chloramphenicol, and the smallest for gentamicin, trimethoprim/sulphamethoxazole. The treatment of 155 representative E. coli isolates from farmed and wild animals in the Mekong Delta (Vietnam) with phenyl-arginine beta-naphthylamide (PAβN), a generic efflux pump inhibitor, resulted in reductions in the prevalence of AMR ranging from 0.7% to 3.3% in these organisms, indicating a small contribution of efflux pumps on the observed prevalence of AMR on farms. These results suggest that the mass usage of commercial disinfectants, many of which contain QACs, is potentially a contributing factor on the generation and maintenance of AMR in animal production in Vietnam.

  1. The Mekong Fish Network: expanding the capacity of the people and institutions of the Mekong River Basin to share information and conduct standardized fisheries monitoring

    USGS Publications Warehouse

    Patricio, Harmony C.; Ainsley, Shaara M.; Andersen, Matthew E.; Beeman, John W.; Hewitt, David A.

    2012-01-01

    The Mekong River is one of the most biologically diverse rivers in the world, and it supports the most productive freshwater fisheries in the world. Millions of people in the Lower Mekong River Basin (LMB) countries of the Union of Myanmar (Burma), Lao People’s Democratic Republic, the Kingdom of Thailand, the Kingdom of Cambodia, and the Socialist Republic of Vietnam rely on the fisheries of the basin to provide a source of protein. The Mekong Fish Network Workshop was convened in Phnom Penh, Cambodia, in February 2012 to discuss the potential for coordinating fisheries monitoring among nations and the utility of establishing standard methods for short- and long-term monitoring and data sharing throughout the LMB. The concept for this network developed out of a frequently cited need for fisheries researchers in the LMB to share their knowledge with other scientists and decisionmakers. A fish monitoring network could be a valuable forum for researchers to exchange ideas, store data, or access general information regarding fisheries studies in the LMB region. At the workshop, representatives from governments, nongovernmental organizations, and universities, as well as participating foreign technical experts, cited a great need for more international cooperation and technical support among them. Given the limited staff and resources of many institutions in the LMB, the success of the proposed network would depend on whether it could offer tools that would provide benefits to network participants. A potential tool discussed at the workshop was a user-friendly, Web-accessible portal and database that could help streamline data entry and storage at the institutional level, as well as facilitate communication and data sharing among institutions. The workshop provided a consensus to establish pilot standardized data collection and database efforts that will be further reviewed by the workshop participants. Overall, workshop participants agreed that this is the type of

  2. Assessment of plastic waste generation and its potential recycling of household solid waste in Can Tho City, Vietnam.

    PubMed

    Thanh, Nguyen Phuc; Matsui, Yasuhiro; Fujiwara, Takeshi

    2011-04-01

    Plastic solid waste has become a serious problem when considering the disposal alternatives following the sequential hierarchy of sound solid waste management. This study was undertaken to assess the quantity and composition of household solid waste, especially plastic waste to identify opportunities for waste recycling. A 1-month survey of 130 households was carried out in Can Tho City, the capital city of the Mekong Delta region in southern Vietnam. Household solid waste was collected from each household and classified into ten physical categories; especially plastic waste was sorted into 22 subcategories. The average household solid waste generation rate was 281.27 g/cap/day. The compostable and recyclable shares respectively accounted for high percentage as 80.74% and 11%. Regarding plastic waste, the average plastic waste generation rate was 17.24 g/cap/day; plastic packaging and plastic containers dominated with the high percentage, 95.64% of plastic waste. Plastic shopping bags were especially identified as the major component, accounting for 45.72% of total plastic waste. Relevant factors such as household income and household size were found to have an existing correlation to plastic waste generation in detailed composition. The household habits and behaviors of plastic waste discharge and the aspects of environmental impacts and resource consumption for plastic waste disposal alternatives were also evaluated.

  3. Malaria in the Greater Mekong Subregion: Heterogeneity and Complexity

    PubMed Central

    Cui, Liwang; Yan, Guiyun; Sattabongkot, Jetsumon; Cao, Yaming; Chen, Bin; Chen, Xiaoguang; Fan, Qi; Fang, Qiang; Jongwutiwes, Somchai; Parker, Daniel; Sirichaisinthop, Jeeraphat; Kyaw, Myat Phone; Su, Xin-zhuan; Yang, Henglin; Yang, Zhaoqing; Wang, Baomin; Xu, Jianwei; Zheng, Bin; Zhong, Daibin; Zhou, Guofa

    2011-01-01

    The Greater Mekong Subregion (GMS), comprised of six countries including Cambodia, China's Yunnan Province, Lao PDR, Myanmar (Burma), Thailand and Vietnam, is one of the most threatening foci of malaria. Since the initiation of the WHO's Mekong Malaria Program a decade ago, malaria situation in the GMS has greatly improved, reflected in the continuous decline in annual malaria incidence and deaths. However, as many nations are moving towards malaria elimination, the GMS nations still face great challenges. Malaria epidemiology in this region exhibits enormous geographical heterogeneity with Myanmar and Cambodia remaining high-burden countries. Within each country, malaria distribution is also patchy, exemplified by ‘border malaria’ and ‘forest malaria’ with high transmission occurring along international borders and in forests or forest fringes, respectively. ‘Border malaria’ is extremely difficult to monitor, and frequent malaria introductions by migratory human populations constitute a major threat to neighboring, malaria-eliminating countries. Therefore, coordination between neighboring countries is essential for malaria elimination from the entire region. In addition to these operational difficulties, malaria control in the GMS also encounters several technological challenges. Contemporary malaria control measures rely heavily on effective chemotherapy and insecticide control of vector mosquitoes. However, the spread of multidrug resistance and potential emergence of artemisinin resistance in Plasmodium falciparum make resistance management a high priority in the GMS. This situation is further worsened by the circulation of counterfeit and substandard artemisinin-related drugs. In most endemic areas of the GMS, P. falciparum and P. vivax coexist, and in recent malaria control history, P. vivax has demonstrated remarkable resilience to control measures. Deployment of the only registered drug (primaquine) for the radical cure of vivax malaria is

  4. Estimating the Burden of Japanese Encephalitis Virus and Other Encephalitides in Countries of the Mekong Region

    PubMed Central

    Tarantola, Arnaud; Goutard, Flavie; Newton, Paul; de Lamballerie, Xavier; Lortholary, Olivier; Cappelle, Julien; Buchy, Philippe

    2014-01-01

    Diverse aetiologies of viral and bacterial encephalitis are widely recognized as significant yet neglected public health issues in the Mekong region. A robust analysis of the corresponding health burden is lacking. We retrieved 75 articles on encephalitis in the region published in English or in French from 1965 through 2011. Review of available data demonstrated that they are sparse and often derived from hospital-based studies with significant recruitment bias. Almost half (35 of 75) of articles were on Japanese encephalitis virus (JEV) alone or associated with dengue. In the Western Pacific region the WHO reported 30,000–50,000 annual JEV cases (15,000 deaths) between 1966 and 1996 and 4,633 cases (200 deaths) in 2008, a decline likely related to the introduction of JEV vaccination in China, Vietnam, or Thailand since the 1980s. Data on dengue, scrub typhus and rabies encephalitis, among other aetiologies, are also reviewed and discussed. Countries of the Mekong region are undergoing profound demographic, economic and ecological change. As the epidemiological aspects of Japanese encephalitis (JE) are transformed by vaccination in some countries, highly integrated expert collaborative research and objective data are needed to identify and prioritize the human health, animal health and economic burden due to JE and other pathogens associated with encephalitides. PMID:24498443

  5. Urbanization and climate change impacts on future urban flooding in Can Tho city, Vietnam

    NASA Astrophysics Data System (ADS)

    Huong, H. T. L.; Pathirana, A.

    2013-01-01

    Urban development increases flood risk in cities due to local changes in hydrological and hydrometeorological conditions that increase flood hazard, as well as to urban concentrations that increase the vulnerability. The relationship between the increasing urban runoff and flooding due to increased imperviousness is better perceived than that between the cyclic impact of urban growth and the urban rainfall via microclimatic changes. The large-scale, global impacts due to climate variability and change could compound these risks. We present the case of a typical third world city - Can Tho (the biggest city in Mekong River Delta, Vietnam) - faced with multiple future challenges, namely: (i) the likely effect of climate change-driven sea level rise, (ii) an expected increase of river runoff due to climate change as estimated by the Vietnamese government, (iii) increased urban runoff driven by imperviousness, and (iv) enhancement of extreme rainfall due to urban growth-driven, microclimatic change (urban heat islands). A set of model simulations were used to construct future scenarios, combining these influences. Urban growth of the city was projected up to year 2100 based on historical growth patterns, using a land use simulation model (Dinamica EGO). A dynamic limited-area atmospheric model (WRF), coupled with a detailed land surface model with vegetation parameterization (Noah LSM), was employed in controlled numerical experiments to estimate the anticipated changes in extreme rainfall patterns due to urban heat island effect. Finally, a 1-D/2-D coupled urban-drainage/flooding model (SWMM-Brezo) was used to simulate storm-sewer surcharge and surface inundation to establish the increase in the flood hazard resulting from the changes. The results show that under the combined scenario of significant change in river level (due to climate-driven sea level rise and increase of flow in the Mekong) and "business as usual" urbanization, the flooding of Can Tho could increase

  6. Building Exposure Maps Of Urban Infrastructure And Crop Fields In The Mekong River Basin

    NASA Astrophysics Data System (ADS)

    Haas, E.; Weichselbaum, J.; Gangkofner, U.; Miltzer, J.; Wali, A.

    2013-12-01

    In the frame of the Integrated Water Resources Management (IWRM) initiative for the Mekong river basin World Bank is collaborating with the Mekong River Commission and governmental organizations in Cambodia, Lao PDR, Thailand and Vietnam to build national and regional capacities for managing the risks associated with natural disasters, such as floods, flash floods and droughts. Within ‘eoworld', a joint initiative set up by ESA and World Bank to foster the use of Earth Observation (EO) for sustainable development work, a comprehensive database of elements at risk in the Lower Mekong river basin has been established by GeoVille, including urban infrastructure and crops (primarily rice paddies). In the long term, this exposure information shall be fed into an open-source multi- hazard modeling tool for risk assessment along the Mekong River, which then shall be used by national stakeholders as well as insurance and financial institutions for planning, disaster preparedness and emergency management. Earth Observation techniques can provide objective, synoptic and repetitive observations of elements at risk including buildings, infrastructure and crops. Through the fusion of satellite-based with in-situ data from field surveys and local knowledge (e.g. on building materials) features at risk can be characterised and mapped with high accuracy. Earth Observation data utilised comprise bi-weekly Envisat ASAR imagery programmed for a period of 9 months in 2011 to map the development of the rice cultivation area, identify predominant cropping systems (wet-season vs. dry season cultivation), crop cycles (single /double / triple crop per year), date of emergence/harvest and the distinction between rice planted under intensive (SRI) vs. regular rice cultivation techniques. Very High Resolution (VHR) optical data from SPOT, KOMPSAT and QuickBird were used for mapping of buildings and infrastructure, such as building footprints, residential / commercial areas, industrial

  7. China on the Mekong: Legitimacy Imperatives and Policy Case Studies

    DTIC Science & Technology

    2013-12-01

    COVERED Master’s Thesis 4. TITLE AND SUBTITLE CHINA ON THE MEKONG: LEGITIMACY IMPERATIVES AND POLICY CASE STUDIES 5. FUNDING NUMBERS 6. AUTHOR...1  A.  MAJOR RESEARCH QUESTION...ADB Asian Development Bank AMBDC ASEAN Mekong Basin Development Cooperation ASEAN Association of Southeast Asian Nations ATS amphetamine -type

  8. Bayesian modeling approach for characterizing groundwater arsenic contamination in the Mekong River basin.

    PubMed

    Cha, YoonKyung; Kim, Young Mo; Choi, Jae-Woo; Sthiannopkao, Suthipong; Cho, Kyung Hwa

    2016-01-01

    In the Mekong River basin, groundwater from tube-wells is a major drinking water source. However, arsenic (As) contamination in groundwater resources has become a critical issue in the watershed. In this study, As species such as total As (AsTOT), As(III), and As(V), were monitored across the watershed to investigate their characteristics and inter-relationships with water quality parameters, including pH and redox potential (Eh). The data illustrated a dramatic change in the relationship between AsTOT and Eh over a specific Eh range, suggesting the importance of Eh in predicting AsTOT. Thus, a Bayesian change-point model was developed to predict AsTOT concentrations based on Eh and pH, to determine changes in the AsTOT-Eh relationship. The model captured the Eh change-point (∼-100±15mV), which was compatible with the data. Importantly, the inclusion of this change-point in the model resulted in improved model fit and prediction accuracy; AsTOT concentrations were strongly negatively related to Eh values higher than the change-point. The process underlying this relationship was subsequently posited to be the reductive dissolution of mineral oxides and As release. Overall, AsTOT showed a weak positive relationship with Eh at a lower range, similar to those commonly observed in the Mekong River basin delta. It is expected that these results would serve as a guide for establishing public health strategies in the Mekong River Basin.

  9. EPA Collaboration with Vietnam

    EPA Pesticide Factsheets

    Vietnam, one of Asia’s emerging economies, is an important environmental partner for EPA in Asia. EPA’s current cooperation with Vietnam primarily focuses on dioxin remediation and technical assistance to reduce methane emissions.

  10. Land cover, land use, and climate change impacts on agriculture in southern Vietnam

    NASA Astrophysics Data System (ADS)

    Kontgis, Caitlin

    Global environmental change is rapidly changing the surface of the Earth in varied and irrevocable ways. Across the world, land cover and land use have been altered to accommodate the needs of expanding populations, and climate change has required plant, animal, and human communities to adapt to novel climates. These changes have created unprecedented new ecosystems that affect the planet in ways that are not fully understood and difficult to predict. Of utmost concern is food security, and whether agro-ecosystems will adapt and respond to widespread changes so that growing global populations can be sustained. To understand how one staple food crop, rice, responds to global environmental change in southern Vietnam, this dissertation aims to accomplish three main tasks: (1) quantify the rate and form of urban and peri-urban expansion onto cropland using satellite imagery and demographic data, (2) track changes to annual rice paddy harvests using time series satellite data, and (3) model the potential effects of climate change on rice paddies by incorporating farmer interview data into a crop systems model. The results of these analyses show that the footprint of Ho Chi Minh City grew nearly five times between 1990 and 2012. Mismatches between urban development and population growth suggest that peri-urbanization is driven by supply-side investment, and that much of this form of land expansion has occurred near major transit routes. In the nearby Mekong River Delta, triple-cropped rice paddy area doubled between 2000 and 2010, from one-third to two-thirds of rice fields, while paddy area expanded by about 10%. These results illustrate the intensification of farming practices since Vietnam liberalized its economy, yet it is not clear whether such practices are environmentally sustainable long-term. Although triple-cropped paddy fields have expanded, future overall production is estimated to decline without the effects of CO2 fertilization. Temperatures are anticipated

  11. Vietnam: Historians at War

    ERIC Educational Resources Information Center

    Moyar, Mark

    2008-01-01

    Although the Vietnam War ended more than thirty years ago, historians remain as divided on what happened as the American people were during the war. Mark Moyar maps the ongoing battle between "orthodox" and "revisionist" Vietnam War historians: the first group, those who depict Vietnam as a bad war that the United States should…

  12. Assessing Malaria Risks in Greater Mekong Subregion based on Environmental Parameters

    NASA Technical Reports Server (NTRS)

    Kiang, Richard; Soika, Valerii; Adimi, Farida; Nigro, Joseph

    2005-01-01

    At 4,200 km, the Mekong River is the tenth longest river in the world. It directly and indirectly influences the lives of hundreds of millions of inhabitants in its basin. The riparian countries - Thailand, Myanmar, Cambodia, Laos, Vietnam, and a small part of China - form the Greater Mekong Subregion (GMS). This geographical region has the misfortune of being the world's epicenter of falciparum malaria, which is the most severe form of malaria caused by Plasmodium falciparum. Depending on the country, approximately 50 to 90% of all malaria cases are due to this species. In the Malaria Modeling and Surveillance Project, we have been developing techniques to enhance public health s decision capability for malaria risk assessments and controls. The main objectives are: 1) identifying the potential breeding sites for major vector species; 2) implementing a malaria transmission model to identify the key factors that sustain or intensify malaria transmission; and 3) implementing a risk algorithm to predict the occurrence of malaria and its transmission intensity. The potential benefits are: 1) increased warning time for public health organizations to respond to malaria outbreaks; 2) optimized utilization of pesticide and chemoprophylaxis; 3) reduced likelihood of pesticide and drug resistance; and 4) reduced damage to environment. Environmental parameters important to malaria transmission include temperature, relative humidity, precipitation, and vegetation conditions. The NASA Earth science data sets that have been used for malaria surveillance and risk assessment include AVHRR Pathfinder, TRMM, MODIS, NSIPP, and SIESIP. Hindcastings based on these environmental parameters have shown good agreement to epidemiological records. Socioeconomic factors that may influence malaria transmissions will also be incorporated into the predictive models.

  13. Sediment dynamics in the lower Mekong River: Transition from tidal river to estuary

    NASA Astrophysics Data System (ADS)

    Nowacki, Daniel J.; Ogston, Andrea S.; Nittrouer, Charles A.; Fricke, Aaron T.; Van, Pham Dang Tri

    2015-09-01

    A better understanding of flow and sediment dynamics in the lowermost portions of large-tropical rivers is essential to constraining estimates of worldwide sediment delivery to the ocean. Flow velocity, salinity, and suspended-sediment concentration were measured for 25 h at three cross sections in the tidal Song Hau distributary of the Mekong River, Vietnam. Two campaigns took place during comparatively high-seasonal and low-seasonal discharge, and estuarine conditions varied dramatically between them. The system transitioned from a tidal river with ephemeral presence of a salt wedge during high flow to a partially mixed estuary during low flow. The changing freshwater input, sediment sources, and estuarine characteristics resulted in seaward sediment export during high flow and landward import during low flow. The Dinh An channel of the Song Hau distributary exported sediment to the coast at a rate of about 1 t s-1 during high flow and imported sediment in a spatially varying manner at approximately 0.3 t s-1 during low flow. Scaling these values results in a yearly Mekong sediment discharge estimate about 65% smaller than a generally accepted estimate of 110 Mt yr-1, although the limited temporal and spatial nature of this study implies a relatively high degree of uncertainty for the new estimate. Fluvial advection of sediment was primarily responsible for the high-flow sediment export. Exchange-flow and tidal processes, including local resuspension, were principally responsible for the low-flow import. The resulting bed-sediment grain size was coarser and more variable during high flow and finer during low, and the residual flow patterns support the maintenance of mid-channel islands. This article was corrected on 7 OCT 2015. See the end of the full text for details.

  14. Spatio-temporal patterns of soil erosion and suspended sediment dynamics in the Mekong River Basin.

    PubMed

    Suif, Zuliziana; Fleifle, Amr; Yoshimura, Chihiro; Saavedra, Oliver

    2016-10-15

    Understanding of the distribution patterns of sediment erosion, concentration and transport in river basins is critically important as sediment plays a major role in river basin hydrophysical and ecological processes. In this study, we proposed an integrated framework for the assessment of sediment dynamics, including soil erosion (SE), suspended sediment load (SSL) and suspended sediment concentration (SSC), and applied this framework to the Mekong River Basin. The Revised Universal Soil Loss Equation (RUSLE) model was adopted with a geographic information system to assess SE and was coupled with a sediment accumulation and a routing scheme to simulate SSL. This framework also analyzed Landsat imagery captured between 1987 and 2000 together with ground observations to interpolate spatio-temporal patterns of SSC. The simulated SSL results from 1987 to 2000 showed the relative root mean square error of 41% and coefficient of determination (R(2)) of 0.89. The polynomial relationship of the near infrared exoatmospheric reflectance and the band 4 wavelength (760-900nm) to the observed SSC at 9 sites demonstrated the good agreement (overall relative RMSE=5.2%, R(2)=0.87). The result found that the severe SE occurs in the upper (China and Lao PDR) and lower (western part of Vietnam) regions. The SSC in the rainy season (June-November) showed increasing and decreasing trends longitudinally in the upper (China and Lao PDR) and lower regions (Cambodia), respectively, while the longitudinal profile of SSL showed a fluctuating trend along the river in the early rainy season. Overall, the results described the unique spatio-temporal patterns of SE, SSL and SSC in the Mekong River Basin. Thus, the proposed integrated framework is useful for elucidating complex process of sediment generation and transport in the land and river systems of large river basins.

  15. [Vietnam and its population].

    PubMed

    Veron, J

    1993-01-01

    80% rural. The population is concentrated in the Red River delta, the Mekong delta, and the southeastern region including Ho Chi Minh City. The 4 main cities are Ho Chi Minh City with 3.2 million inhabitants,. Hanoi with 1.1 million, Hai Phong with 456,000, and Da Nang with 371,000. Although internal migration has not yet assumed great weight, there has been some rural exodus and movement from poor to richer regions. The policy of population redistribution to reduce density in the Red River delta and central coastal plain and to control city growth has led to some movement. 88% of the population over 10 was literate in 1989. Almost 75% of the population over age 13 is economically active. 71% of the economically active population is employed in agriculture, 12% in industry, and 7% in commerce. If current growth trends continue, Viet Nam is projected to have a population of 80 million in 2000 and 96 million in 2014.

  16. Copper toxicity and the influence of water quality of Dongnai River and Mekong River waters on copper bioavailability and toxicity to three tropical species.

    PubMed

    Bui, Thanh-Khiet L; Do-Hong, L Chi; Dao, Thanh-Son; Hoang, Tham C

    2016-02-01

    The present study investigated copper (Cu) toxicity and the influence of water quality characteristics of Dongnai River and Mekong River (Vietnam) surface waters to three tropical species; Daphnia lumholtzi, Ceriodaphnia cornuta, and Danio rerio. The river waters had a range of water quality parameters that modify Cu bioavailability and toxicity. The range of total hardness, alkalinity, pH and dissolved organic carbon were 15-64 mg/L as CaCO3, 18-58 mg/L as CaCO3, 6.62-7.88, and 6.9-14.7 mg/l, respectively. The US EPA acute toxicity test method with a modification to the light photoperiod and temperature for tropical organisms was used to investigate Cu toxicity. Result of the present study found that Cu produced toxic effect to the studied organisms at low concentrations. The 48-h LC50 ranged from 3.92 to 8.61 µg/l, 2.92-9.56 µg/l, and 15.71-68.69 µg/l dissolved Cu for D. lumholtzi, C. cornuta, and D. rerio, respectively. In general, water quality had an influence on Cu bioavailability and toxicity to the studied organisms. The toxicity of Cu was higher in water with lower hardness, DOC, and/or pH. The present study indicates a contribution of Cu hydroxide and carbonate to Cu bioavailability to Mekong organisms. Results of the present study will be used for calibrating the US Cu Biotic Ligand Model (BLM) to Mekong River water and organisms in support of application of the BLM for setting site-specific Cu water quality guidelines in the ecosystem of the Lower Mekong River Basin.

  17. Knockdown resistance in Anopheles vagus, An. sinensis, An. paraliae and An. peditaeniatus populations of the Mekong region

    PubMed Central

    2010-01-01

    Background In the Mekong region (Vietnam, Cambodia and Laos), a large investigation was conducted to assess the susceptibility of Anopheles species against DDT and pyrethroids. In this study, the resistance status of the potential malaria vectors An. vagus, An. sinensis, An. paraliae and An. peditaeniatus was assessed. Methods Bioassays were performed on field collected unfed female mosquitoes using the standard WHO susceptibility tests. In addition, the DIIS6 region of the para-type sodium channel gene was amplified and sequenced and four allele-specific PCR assays were developed to assess the kdr frequencies. Results In Southern Vietnam all species were DDT and pyrethroid resistant, which might suggest the presence of a kdr resistance mechanism. Sequence-analysis of the DIIS6 region of the para-type sodium channel gene revealed the presence of a L1014S kdr mutation in An. vagus, An. sinensis and An. paraliae. In An. peditaeniatus, a low frequency L1014S kdr mutation was found in combination with a high frequency L1014F kdr mutation. For pyrethroids and DDT, no genotypic differentiation was found between survivors and non-survivors for any of these species. In the two widespread species, An. vagus and An. sinensis, kdr was found only in southern Vietnam and in Cambodia near the Vietnamese border. Conclusions Different levels of resistance were measured in Laos, Cambodia and Vietnam. The kdr mutation in different Anopheles species seems to occur in the same geographical area. These species breed in open agricultural lands where malaria endemicity is low or absent and vector control programs less intensive. It is therefore likely that the selection pressure occurred on the larval stages by insecticides used for agricultural purposes. PMID:20646327

  18. DELTAS: A new Global Delta Sustainability Initiative (Invited)

    NASA Astrophysics Data System (ADS)

    Foufoula-Georgiou, E.

    2013-12-01

    , Vietnam, and Canada. Key components of the DELTAS Sustainability Initiative are: integrated research on deltas as coupled socio-ecological systems undergoing change (Delta-SRES), a global delta data depository (Delta-DAT), a suite of open access delta risk assessment and decision support modeling tools (Delta-RADS), and the coordinated demonstration of these activities in deltas around the world (Delta-ACT).

  19. Vietnam plunges ahead

    SciTech Connect

    Burr, M.T.

    1995-07-01

    Vietnam is moving fast. Facing the need to double its installed power generation capacity by the year 2000, Vietnam is pursuing a range of development alternatives to add an estimated 3,000 MW of new power plants. As part of the country`s progress toward a market economy, Vietnam has relaxed its rules regarding investment in power plants. The country enacted a new electricity law early in 1995, paving the way for private participation in the power sector.

  20. Vietnam Education in New England.

    ERIC Educational Resources Information Center

    Banit, Thomas

    1990-01-01

    Outlines reasons why teaching about Vietnam is important. Presents the results of a survey designed to find out what New England teachers are teaching about Vietnam. Critiques textbooks on the Vietnam War, and offers teaching strategies for Vietnam War instruction. Recommends the use of maps, films, and videos. (RW)

  1. Possible Source Populations of the White-backed Planthopper in the Greater Mekong Subregion Revealed by Mitochondrial DNA Analysis

    NASA Astrophysics Data System (ADS)

    Li, Xiang-Yong; Chu, Dong; Yin, Yan-Qiong; Zhao, Xue-Qing; Chen, Ai-Dong; Khay, Sathya; Douangboupha, Bounneuang; Kyaw, Mu Mu; Kongchuensin, Manita; Ngo, Vien Vinh; Nguyen, Chung Huy

    2016-12-01

    The white-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae), is a serious pest of rice in Asia. However, little is known regarding the migration of this pest insect from the Greater Mekong Subregion (GMS) including Cambodia, Laos, Myanmar (Burma), Thailand, and Vietnam, into China’s Yunnan Province. To determine the migration patterns of S. furcifera in the GMS and putative secondary immigration inside China’s Yunnan Province, we investigated the population genetic diversity, genetic structure, and gene flow of 42 S. furcifera populations across the six countries in the GMS by intensive sampling using mitochondrial genes. Our study revealed the potential emigration of S. furcifera from the GMS consists primarily of three major sources: 1) the S. furcifera from Laos and Vietnam migrate into south and southeast Yunnan, where they proceed to further migrate into northeast and central Yunnan; 2) the S. furcifera from Myanmar migrate into west Yunnan, and/or central Yunnan, and/or northeast Yunnan; 3) the S. furcifera from Cambodia migrate into southwest Yunnan, where the populations can migrate further into central Yunnan. The new data will not only be helpful in predicting population dynamics of the planthopper, but will also aid in regional control programs for this economically important pest insect.

  2. Possible Source Populations of the White-backed Planthopper in the Greater Mekong Subregion Revealed by Mitochondrial DNA Analysis

    PubMed Central

    Li, Xiang-yong; Chu, Dong; Yin, Yan-qiong; Zhao, Xue-qing; Chen, Ai-dong; Khay, Sathya; Douangboupha, Bounneuang; Kyaw, Mu Mu; Kongchuensin, Manita; Ngo, Vien Vinh; Nguyen, Chung Huy

    2016-01-01

    The white-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae), is a serious pest of rice in Asia. However, little is known regarding the migration of this pest insect from the Greater Mekong Subregion (GMS) including Cambodia, Laos, Myanmar (Burma), Thailand, and Vietnam, into China’s Yunnan Province. To determine the migration patterns of S. furcifera in the GMS and putative secondary immigration inside China’s Yunnan Province, we investigated the population genetic diversity, genetic structure, and gene flow of 42 S. furcifera populations across the six countries in the GMS by intensive sampling using mitochondrial genes. Our study revealed the potential emigration of S. furcifera from the GMS consists primarily of three major sources: 1) the S. furcifera from Laos and Vietnam migrate into south and southeast Yunnan, where they proceed to further migrate into northeast and central Yunnan; 2) the S. furcifera from Myanmar migrate into west Yunnan, and/or central Yunnan, and/or northeast Yunnan; 3) the S. furcifera from Cambodia migrate into southwest Yunnan, where the populations can migrate further into central Yunnan. The new data will not only be helpful in predicting population dynamics of the planthopper, but will also aid in regional control programs for this economically important pest insect. PMID:27991532

  3. In Vietnam, Manufacturing Masterworks

    ERIC Educational Resources Information Center

    Overland, Martha Ann

    2006-01-01

    Vietnam, with its cheap labor and lax copyright laws, is a counterfeiter's dream. Books are sold hot off the photocopier and Hollywood's latest blockbusters can be had on DVD's for about a dollar. But it is in art forgery that Vietnam excels. With a stable of neoclassically trained art students, who spend years learning to copy the masters, art…

  4. Physical Education in Vietnam.

    ERIC Educational Resources Information Center

    Waigandt, Alex; Cox, Richard H.

    1994-01-01

    Discusses education in general in Vietnam, focusing on Vietnam's system of physical education. Researchers examined government documents and interviewed government officials, teachers, and students to gather information. Results indicated the Vietnamese government has made a commitment to education, though the quality of education has not kept up…

  5. Urbanization and climate change impacts on future urban flood risk in Can Tho city, Vietnam

    NASA Astrophysics Data System (ADS)

    Huong, H. T. L.; Pathirana, A.

    2011-12-01

    Urban development increases flood risk in cities due to local changes in hydrological and hydrometeorological conditions that increase flood hazard, and also to urban concentrations that increase the vulnerability. The relationship between the increasing urban runoff and flooding due to increased imperviousness better perceived than that between the cyclic impact of urban growth and the urban rainfall via microclimatic changes. The large-scale, global impacts due to climate variability and change could compound these risks. We present the case of a typical third world city - Can Tho (the biggest city in Mekong River Delta, Vietnam) - faced with multiple future challenges, namely: (i) climate change-driven sea-level rise and tidal effect, (ii) increase river runoff due to climate change, (iii) increased urban runoff driven by imperviousness, and (iv) enhancement of extreme rainfall due to urban growth-driven micro-climatic change (urban heat islands). A set of model simulations were used to assess the future impact of the combination of these influences. Urban growth of the city was projected up to year 2100 based on historical growth patterns, using a land-use simulation model (Dinamica-EGO). A dynamic limited-area atmospheric model (WRF), coupled with a detailed land-surface model with vegetation parameterization (Noah LSM), was employed in controlled numerical experiments to estimate the anticipated changes in extreme rainfall patterns due to urban heat island effect. Finally, a 1-D/2-D coupled urban-drainage/flooding model (SWMM-Brezo) was used to simulate storm-sewer surcharge and surface inundation to establish the increase in the flood risk resulting from the changes. The results show that, if the city develops as predicted, the maximum of inundation depth and area in Can Tho will increase by about 20%. The impact of climate change on inundation is more serious than that of urbanization. The worse case may occur if the sea level rises 100 cm and the flow from

  6. Nile Delta

    Atmospheric Science Data Center

    2013-04-15

    article title:  The Nile River Delta     View Larger Image ... of eastern Africa. At the apex of the fertile Nile River Delta is the Egyptian capital city of Cairo. To the west are the Great Pyramids ...

  7. The heat flow study in the Tertiary Basin of Vietnam offshore

    SciTech Connect

    Huyen, T.

    1994-07-01

    In Vietnam, study of heat flow has paralleled petroleum exploration activities. For a long time there had only been results on temperature gradients in the Tertiary basin. Recently, with its participation in CCOP's project on the establishment of heat flow regional maps (1992-1993) and the government's mineral resources program (1993-1995) (Coded KT-01-18), Vietnam Petroleum Institute's group on heat flow obtained results on heat flow. A heat flow study in the oil basinal area in Vietnam has been conducted using data from 76 exploratory wells. Thermal conductivity of 427 cores was measured using the quick thermal conductivity meter (QTM) within temperature gradients of wells calculated from well log data and from testing data. The average heat flow of sedimentary basins in Vietnam follows: Hanoi graben, 125 Q (mW/m2); north Gulf of Tonkin, 87 Q (mW/m2); south Gulf of Tonkin, 119 Q (mW/m2); Danang Graben, 89 Q (mW/m2); northeast-south Conson, 88 Q (mW/m2); southwest-south Conson, 85 Q (mW/m2); Mekong Basin, 64 Q (mW/m2).

  8. Volga Delta

    Atmospheric Science Data Center

    2013-04-17

    article title:  Volga Delta and the Caspian Sea     View ... appear reddish. A small cloud near the center of the delta separates into red, green, and blue components due to geometric parallax ... include several linear features located near the Volga Delta shoreline. These long, thin lines are artificially maintained shipping ...

  9. The U.S. Marine Corps Combined Action Program (CAP): A Proposed Alternative Strategy for the Vietnam War

    DTIC Science & Technology

    2002-05-01

    PF counterparts. Their cohabitation assured the villagers of their security, allowing relations between these two diverse cultures to thrive. The...This is not to say that the CAP was without fault. Differences of language and culture plagued the program throughout its duration. Although the...that of the Mekong River delta. Given the violent history of the land coupled with its undeveloped, rice cultured people, Ho Chi Minh’s application

  10. RMIT Vietnam and Vietnam's Development: Risk and Responsibility

    ERIC Educational Resources Information Center

    Wilmoth, David

    2004-01-01

    To help bridge the gap between demand and supply for tertiary education, Vietnam has opened to direct, foreign providers, and the Royal Melbourne Institute of Technology (RMIT) International University Vietnam is the first of this category. By sponsoring a large project in a country that some see as risky, RMIT Vietnam needs to be triply viable.…

  11. Vietnam and American Government Textbooks.

    ERIC Educational Resources Information Center

    Cline, Paul C.; Eksterowicz, Anthony J.

    1998-01-01

    Discusses the importance of studying the Vietnam War. Attempts to illustrate the amount and quality of coverage of the Vietnam War in U.S. government textbooks. Explains that the amount of space devoted to the war in most of these texts remains inadequate for student understanding of the Vietnam War. (CMK)

  12. Modeling transport and deposition of the Mekong River sediment

    USGS Publications Warehouse

    Xue, Zuo; He, Ruoying; Liu, J. Paul; Warner, John C.

    2012-01-01

    A Coupled Wave–Ocean–SedimentTransport Model was used to hindcast coastal circulation and fine sedimenttransport on the Mekong shelf in southeastern Asian in 2005. Comparisons with limited observations showed that the model simulation captured the regional patterns and temporal variability of surface wave, sea level, and suspended sediment concentration reasonably well. Significant seasonality in sedimenttransport was revealed. In summer, a large amount of fluvial sediments was delivered and deposited near the MekongRiver mouth. In the following winter, strong ocean mixing, and coastal current lead to resuspension and southwestward dispersal of a small fraction of previously deposited sediments. Model sensitivity experiments (with reduced physics) were performed to investigate the impact of tides, waves, and remotely forced ambient currents on the transport and dispersal of the fluvial sediment. Strong wave mixing and downwelling-favorable coastal current associated with the more energetic northeast monsoon in the winter season are the main factors controlling the southwestward along-shelf transport.

  13. Caring for Vietnam Veterans.

    PubMed

    Elliott, Brenda

    2015-01-01

    Veterans of the Vietnam era are now the largest group of United States Veterans, and are at or approaching Social Security and Medicare eligibility. As a result, it is likely that home care clinicians will be caring for many patients who are Vietnam Veterans. The purpose of this article is to increase awareness of the unique healthcare needs of Vietnam Veterans. Having an understanding of military and Veteran culture can help inform home healthcare clinicians in ways to manage the unique healthcare needs of Veterans and engage previously learned behaviors and attitudes from military service. In addition, knowing the types of exposures and health risks specific to this era could be beneficial in identifying potential problems that may have not yet been addressed.

  14. Impacts of Seasonal Flooding on Arsenic Release in Tropical River Deltas

    NASA Astrophysics Data System (ADS)

    Roberts, K. A.; Fendorf, S. E.; Schaefer, M.; Benner, S. G.; Salvador, A. K.

    2015-12-01

    More than 140 million people in South and Southeast Asia drink groundwater contaminated with toxic levels of arsenic. Arsenic release from sediment is controlled by oxidation of reduced organic carbon coupled to iron and arsenic reduction; this process occurs principally under anaerobic conditions and is constrained to surficial (<1 m depth) sediments in the Mekong Delta. However, there is limited knowledge of water level changes in seasonal wetlands that control carbon oxidation pathways and subsequently arsenic release from sediments to groundwater. During drained periods, soils undergo aerobic carbon oxidation, diverting electron flow away from iron and arsenic reduction, decreasing arsenic release from sediments to groundwater. Additionally, draining may lead to fresh Fe-oxide precipitation that sequesters As. We monitored soil moisture and porewater chemistry of a seasonal wetland in the Mekong Delta through a wetting and drying cycle. We examined temporal trends in arsenic release from the solid phase over the flooding and drying cycles. Based on frequent field measurements we determine the timing and magnitude of arsenic release in surficial sediments of seasonal wetlands typical of the Mekong Delta. These results show the importance of surface processes on arsenic release and aid in developing mechanistic and predictive models of arsenic concentrations in the subsurface throughout Asia.

  15. Getting Road Expansion on the Right Track: A Framework for Smart Infrastructure Planning in the Mekong.

    PubMed

    Balmford, Andrew; Chen, Huafang; Phalan, Ben; Wang, Mingcheng; O'Connell, Christine; Tayleur, Cath; Xu, Jianchu

    2016-12-01

    The current unprecedented expansion of infrastructure promises to enhance human wellbeing but risks causing substantial harm to natural ecosystems and the benefits they provide for people. A framework for systematically and proactively identifying the likely benefits and costs of such developments is badly needed. Here, we develop and test at the subregional scale a recently proposed global scheme for comparing the potential gains from new roads for food production with their likely impact on biodiversity and ecosystem services. Working in the Greater Mekong-an exceptionally biodiverse subregion undergoing rapid development-we combined maps of isolation from urban centres, yield gaps, and the current area under 17 crops to estimate where and how far road development could in principle help to increase food production without the need for cropland expansion. We overlaid this information with maps summarising the importance of remaining habitats to terrestrial vertebrates and (as examples of major ecosystem services) to global and local climate regulation. This intersection revealed several largely converted yet relatively low-yielding areas (such as central, eastern, and northeastern Thailand and the Ayeyarwady Delta), where narrowing yield gaps by improving transport links has the potential to substantially increase food production at relatively limited environmental cost. Concentrating new roads and road improvements here while taking strong measures to prevent their spread into areas which are still extensively forested (such as northern Laos, western Yunnan, and southwestern Cambodia) could thus enhance rural livelihoods and regional food production while helping safeguard vital ecosystem services and globally significant biological diversity.

  16. Communication and social capital in the control of avian influenza: lessons from behaviour change experiences in the Mekong Region.

    PubMed

    Waisbord, S R; Michaelides, T; Rasmuson, M

    2008-01-01

    International development agencies, national governments, and nongovernmental organizations are increasingly collaborating with local civil society groups in mounting behaviour change communication (BCC) interventions. Even in countries with weakened civil societies, the social capital of local organizations can be a fundamental communication resource. The experience of three programmes in the Mekong Region that used BCC to prevent and control outbreaks of avian influenza bore out this finding. These programmes worked with the Vietnam Women's Union to mobilize local women as conduits for education; worked with the Centre d'Etude et de Developpement Agricole Cambodgien (CEDAC), in Cambodia, to educate and train village health promoters and model farmers; and worked with the Lao Journalists Association to educate and build skills among print and broadcast journalists to enhance avian influenza coverage. Collaborating with civil society organizations can enhance communication reach, trust, and local ownership, but poses many challenges, particularly institutional capacity. Our experience, nevertheless, holds promise for a measured approach that views social capital as a set of communication resources at the community level that can be mobilized to promote complex behaviours, particularly in a rapidly changing outbreak situation.

  17. Natural and Human Impacts on Recent Development of Asian Large Rivers and Deltas

    NASA Astrophysics Data System (ADS)

    Liu, P.; Lu, C.

    2014-12-01

    Most recent data analysis indicates sediment loads in most of Asian large rivers (like, Yellow, Yangtze, Pearl, Chao Phraya, Indus, Krishna, Godavari, etc) have decreased up to 80-90% in the past 60 years. Correspondingly, most of Asian large river deltas are facing severe sediment starving; delta shoreline comparisons indicate that some are under strong coastal erosion. For examples, the Yellow River Delta has been retreating since 1990s when its annual sediment load has kept below 300 million tons. The Yangtze River delta kept growing before Three Gorges Dams was operating, and began to be eroded from the year 2003 to 2009, and then prograded locally due to the Deep Water Navigation Project. The Mekong Delta shoreline has also been dynamically changing with the sediment flux variation, eroding from 1989 to 1996 and prograding from 1996 to 2002. More information is available at http://www.meas.ncsu.edu/sealevel

  18. JPRS Report, East Asia. Southeast Asia, Vietnam: TAP CHI CONG SAN, No. 7, July 1989.

    DTIC Science & Technology

    1990-01-29

    It’s easier to keep on the old path, give up your dreams, and submit to your fate even if things are not pleasant. In the past, we gave too much... House , Hanoi, 1971, p 70. Research—Exchange of Opinions JPRS-ATC-90-001 29 January 1990 Man and Class 00000000 Hanoi TAP CHI CONG SAN in... housing was held recently in the Mekong Delta, but after much discussion, no conclusion was reached about how to overcome the situation in which 70-80

  19. Chemical weathering and CO₂ consumption in the Lower Mekong River.

    PubMed

    Li, Siyue; Lu, X X; Bush, Richard T

    2014-02-15

    Data on river water quality from 42 monitoring stations in the Lower Mekong Basin obtained during the period 1972-1996 was used to relate solute fluxes with controlling factors such as chemical weathering processes. The total dissolved solid (TDS) concentration of the Lower Mekong varied from 53 mg/L to 198 mg/L, and the median (114 mg/L) was compared to the world spatial median value (127 mg/L). Total cationic exchange capacity (Tz(+)) ranged from 729 to 2,607 μmolc/L, and the mean (1,572 μmolc/L) was 1.4 times higher than the world discharge-weighted average. Calcium and bicarbonate dominated the annual ionic composition, accounting for ~70% of the solute load that equalled 41.2×10(9)kg/y. TDS and major elements varied seasonally and in a predictable way with river runoff. The chemical weathering rate of 37.7t/(km(2)y), with respective carbonate and silicate weathering rates of 27.5t/(km(2) y) (13.8mm/ky) and 10.2t/(km(2) y) (3.8mm/ky), was 1.5 times higher than the global average. The CO2 consumption rate was estimated at 191×10(3)molCO2/(km(2)y) for silicate weathering, and 286×10(3)molCO2/(km(2)y) by carbonate weathering. In total, the Mekong basin consumed 228×10(9)molCO2/y and 152×10(9)molCO2/y by the combined weathering of carbonate and silicate, constituting 1.85% of the global CO2 consumption by carbonate weathering and 1.75% by silicates. This is marginally higher than its contribution to global water discharge ~1.3% and much higher than (more than three-fold) its contribution to world land surface area. Remarkable CO2 consumed by chemical weathering (380×10(9)mol/y) was similar in magnitude to dissolved inorganic carbon as HCO3(-) (370×10(9)mol/y) exported by the Mekong to the South China Sea. In this landscape, atmospheric CO2 consumption by rock chemical weathering represents an important carbon sink with runoff and physical erosion controlling chemical erosion.

  20. El Niño Southern Oscillation Influences River Bank Erosion on the Lower Mekong River

    NASA Astrophysics Data System (ADS)

    Darby, S. E.; Trieu, H. Q.; Carling, P. A.

    2009-12-01

    . However, both simulated time series exhibit quasi-periodic oscillations about these means. The Mekong’s flow regime is controlled by variations in meltwater regime, the intensity of the SE Asian monsoon, and the frequency and intensity of tropical cyclones that penetrate inland from the South China Sea. Since melt contributes only to (non-erosive) base flows, variability in glacier and snow melt contributions from Himalayan source areas are unlikely to significantly impact inter-annual variations in river bank erosion. However, inter-annual variability in the SE Asian monsoon and tropical cyclone dynamics may both be related, albeit in a complex manner, to the El Niño Southern Oscillation (ENSO). Cross-wavelet transform and wavelet coherence analyses indicate statistically significant (at 95% limit) coherence between ENSO and simulated river bank erosion, but at both sites only since about 1980. During this recent period the ENSO and fluvial erosion time series are in anti-phase; that is ENSO cold phases are associated with enhanced rates of river bank erosion. This is as expected, since ENSO cold phases are associated with earlier onset and enhanced intensity of the monsoon, while the number of intense tropical storm systems making landfall over Vietnam and moving across the Lower Mekong Basin is also higher.

  1. Teaching about Vietnam and the Vietnam War. ERIC Digest.

    ERIC Educational Resources Information Center

    Schlene, Vicki J.

    This digest discusses the need for teaching about the Vietnam War, possible reasons for the negligible treatment the subject receives in social studies classes, and some instructional approaches to the material. Currently, students lack a systematic and detailed knowledge of this turning point in U.S. history. The impact of the Vietnam War on U.S.…

  2. Flood forecasting for River Mekong with data-based models

    NASA Astrophysics Data System (ADS)

    Shahzad, Khurram M.; Plate, Erich J.

    2014-09-01

    In many regions of the world, the task of flood forecasting is made difficult because only a limited database is available for generating a suitable forecast model. This paper demonstrates that in such cases parsimonious data-based hydrological models for flood forecasting can be developed if the special conditions of climate and topography are used to advantage. As an example, the middle reach of River Mekong in South East Asia is considered, where a database of discharges from seven gaging stations on the river and 31 rainfall stations on the subcatchments between gaging stations is available for model calibration. Special conditions existing for River Mekong are identified and used in developing first a network connecting all discharge gages and then models for forecasting discharge increments between gaging stations. Our final forecast model (Model 3) is a linear combination of two structurally different basic models: a model (Model 1) using linear regressions for forecasting discharge increments, and a model (Model 2) using rainfall-runoff models. Although the model based on linear regressions works reasonably well for short times, better results are obtained with rainfall-runoff modeling. However, forecast accuracy of Model 2 is limited by the quality of rainfall forecasts. For best results, both models are combined by taking weighted averages to form Model 3. Model quality is assessed by means of both persistence index PI and standard deviation of forecast error.

  3. The Lessons of the Vietnam War.

    ERIC Educational Resources Information Center

    Starr, Jerold M., Ed.

    This text book on the Vietnam War is to be used in teaching high students. Each of the volume's 12 chapters is a self-contained unit on an aspect of the War. The chapters are: (1) Introduction to Vietnam: land, history, and culture; (2) America at war in Vietnam: decisions and consequences; (3) Was the Vietnam War legal? (4) who fought for the…

  4. Clade-level Spatial Modelling of HPAI H5N1 Dynamics in the Mekong Region Reveals New Patterns and Associations with Agro-Ecological Factors.

    PubMed

    Artois, Jean; Newman, Scott H; Dhingra, Madhur S; Chaiban, Celia; Linard, Catherine; Cattoli, Giovanni; Monne, Isabella; Fusaro, Alice; Xenarios, Ioannis; Engler, Robin; Liechti, Robin; Kuznetsov, Dmitri; Pham, Thanh Long; Nguyen, Tung; Pham, Van Dong; Castellan, David; Von Dobschuetz, Sophie; Claes, Filip; Dauphin, Gwenaëlle; Inui, Ken; Gilbert, Marius

    2016-07-25

    The highly pathogenic avian influenza (HPAI) H5N1 virus has been circulating in Asia since 2003 and diversified into several genetic lineages, or clades. Although the spatial distribution of its outbreaks was extensively studied, differences in clades were never previously taken into account. We developed models to quantify associations over time and space between different HPAI H5N1 viruses from clade 1, 2.3.4 and 2.3.2 and agro-ecological factors. We found that the distribution of clades in the Mekong region from 2004 to 2013 was strongly regionalised, defining specific epidemiological zones, or epizones. Clade 1 became entrenched in the Mekong Delta and was not supplanted by newer clades, in association with a relatively higher presence of domestic ducks. In contrast, two new clades were introduced (2.3.4 and 2.3.2) in northern Viet Nam and were associated with higher chicken density and more intensive chicken production systems. We suggest that differences in poultry production systems in these different epizones may explain these associations, along with differences in introduction pressure from neighbouring countries. The different distribution patterns found at the clade level would not be otherwise apparent through analysis treating all outbreaks equally, which requires improved linking of disease outbreak records and genetic sequence data.

  5. Clade-level Spatial Modelling of HPAI H5N1 Dynamics in the Mekong Region Reveals New Patterns and Associations with Agro-Ecological Factors

    PubMed Central

    Artois, Jean; Newman, Scott H.; Dhingra, Madhur S.; Chaiban, Celia; Linard, Catherine; Cattoli, Giovanni; Monne, Isabella; Fusaro, Alice; Xenarios, Ioannis; Engler, Robin; Liechti, Robin; Kuznetsov, Dmitri; Pham, Thanh Long; Nguyen, Tung; Pham, Van Dong; Castellan, David; Von Dobschuetz, Sophie; Claes, Filip; Dauphin, Gwenaëlle; Inui, Ken; Gilbert, Marius

    2016-01-01

    The highly pathogenic avian influenza (HPAI) H5N1 virus has been circulating in Asia since 2003 and diversified into several genetic lineages, or clades. Although the spatial distribution of its outbreaks was extensively studied, differences in clades were never previously taken into account. We developed models to quantify associations over time and space between different HPAI H5N1 viruses from clade 1, 2.3.4 and 2.3.2 and agro-ecological factors. We found that the distribution of clades in the Mekong region from 2004 to 2013 was strongly regionalised, defining specific epidemiological zones, or epizones. Clade 1 became entrenched in the Mekong Delta and was not supplanted by newer clades, in association with a relatively higher presence of domestic ducks. In contrast, two new clades were introduced (2.3.4 and 2.3.2) in northern Viet Nam and were associated with higher chicken density and more intensive chicken production systems. We suggest that differences in poultry production systems in these different epizones may explain these associations, along with differences in introduction pressure from neighbouring countries. The different distribution patterns found at the clade level would not be otherwise apparent through analysis treating all outbreaks equally, which requires improved linking of disease outbreak records and genetic sequence data. PMID:27453195

  6. Developing School Psychology in Vietnam

    ERIC Educational Resources Information Center

    Le, Phuong; Hagans, Kristi; Powers, Kristin; Hass, Michael

    2011-01-01

    Like China, Vietnam is a communist country with increasingly capitalist economic policies. A fundamental change occurred in these policies with the enactment of Vietnam's "doi moi" (renovation) policy in 1986 that called for a "free market with socialist orientations." However, this economic modernization has inadvertently…

  7. Dam-Induced Sediment Starvation in Deltas: Implications for the Mekong

    NASA Astrophysics Data System (ADS)

    Kondolf, G. M.; Rubin, Z.; Minear, J. T.

    2014-12-01

    As the climate warms, especially rapid responses are being seen in the Arctic. Melting ice and thawing soils have wide ranging impacts including changes to ecosystems. What that means depends, in no small measure, on your understanding of—and relationship—to the ecosystems as evidenced by the currencies in which you measure ecosystem change. Thus, an ecologist will tend to focus on the impacts on energy flow and organizational complexity; conservationists on ecosystem services and biodiversity; and subsistence hunters on food security and cultural identity. Policy makers (a poorly defined group) will attempt to integrate all of the above within the very real limits of their fluency with each currency. The situation is further complicated by unavoidable ambiguities; abiotic and biotic influences can be difficult to distinguish, scale impacts ecosystem response unevenly, and ecosystems are useful concepts but not amenable to precise boundaries. As the risks of climate change become more evident, the cost of ambiguities and disparate currencies increases. It is imperative that scientists, conservationists, subsistence hunters, and policy makers appreciate and overcome their different ways of understanding environmental change.

  8. Armor in Vietnam

    DTIC Science & Technology

    1976-05-01

    psychological atmosphere of conventional combat and recall the French experience of 1953 and 1954. It is not clear why creating an impression of...Season Going1 1 Corpr I CORPS . WET SEASON DANo " NO 0O, TK-APC O 50 100 KILOMETERG , .-... Wet Season Going, I Corps •[. FIGUIME 16, KEY: "GOTK-APC...version of the U.S. M48; first pro- 1duced in 1953 , the M48A3 was the primary weapon of U.S. tank battalions and armored cavalry units in Vietnam

  9. Deliberation and scale in Mekong region water governance.

    PubMed

    Dore, John; Lebel, Louis

    2010-07-01

    Understanding the politics of deliberation, scales, and levels is crucial to understanding the social complexity of water-related governance. Deliberative processes might complement and inform more conventional representational and bureaucratic approaches to planning and decision-making. However, they are also subject to scale and level politics, which can confound institutionalized decision-making. Scale and level contests arise in dialogues and related arenas because different actors privilege particular temporal or spatial scales and levels in their analysis, arguments, and responses. Scale contests might include whether to privilege administrative, hydrological, ecosystem, or economic boundaries. Level contests might include whether to privilege the subdistrict or the province, the tributary watershed or the international river basin, a river or a biogeographic region, and the local or the regional economy. In the Mekong Region there is a recurrent demand for water resources development projects and major policies proposed by governments and investors to be scrutinized in public. Deliberative forms of engagement are potentially very helpful because they encourage supporters and critics to articulate assumptions and reasoning about the different opportunities and risks associated with alternative options, and in doing so, they often traverse and enable higher-quality conversations within and across scales and within and between levels. Six case studies from the Mekong Region are examined. We find evidence that scale and level politics affects the context, process, content, and outcomes of deliberative engagement in a region where public deliberation is still far from being a norm, particularly where there are sensitive and far-reaching choices to be made about water use and energy production.

  10. Pharmacy education in Vietnam.

    PubMed

    Vo, Thi-Ha; Bedouch, Pierrick; Nguyen, Thi-Hoai; Nguyen, Thi-Lien-Huong; Hoang, Thi-Kim-Huyen; Calop, Jean; Allenet, Benoît

    2013-08-12

    Pharmacy education programs in Vietnam are complex and offer various career pathways. All include theory and laboratory modules in general, foundation, and pharmaceutical knowledge; placements in health facilities; and a final examination. The various pharmacy degree programs allow specialization in 1 or more of 5 main fields: (1) drug management and supply, (2) drug development and production, (3) pharmacology and clinical pharmacy, (4) traditional medicine and pharmacognosy, and (5) drug quality control, which are offered as main specialization options during the reformed undergraduate and postgraduate programs. However, pharmacy education in Vietnam in general remains product oriented and clinical pharmacy training has not received adequate attention. Only students who have obtained the bachelor of pharmacy degree, which requires a minimum of 5 years of study, are considered as fully qualified pharmacists. In contrast, an elementary diploma in pharmacy awarded after 1 year of pharmacy study permits entry into more junior pharmacy positions. Since the 2000s, there has been a surge in the number and types of schools offering pharmacy qualifications at various levels.

  11. Fluvial sediment supply to a mega-delta reduced by shifting tropical-cyclone activity.

    PubMed

    Darby, Stephen E; Hackney, Christopher R; Leyland, Julian; Kummu, Matti; Lauri, Hannu; Parsons, Daniel R; Best, James L; Nicholas, Andrew P; Aalto, Rolf

    2016-11-10

    The world's rivers deliver 19 billion tonnes of sediment to the coastal zone annually, with a considerable fraction being sequestered in large deltas, home to over 500 million people. Most (more than 70 per cent) large deltas are under threat from a combination of rising sea levels, ground surface subsidence and anthropogenic sediment trapping, and a sustainable supply of fluvial sediment is therefore critical to prevent deltas being 'drowned' by rising relative sea levels. Here we combine suspended sediment load data from the Mekong River with hydrological model simulations to isolate the role of tropical cyclones in transmitting suspended sediment to one of the world's great deltas. We demonstrate that spatial variations in the Mekong's suspended sediment load are correlated (r = 0.765, P < 0.1) with observed variations in tropical-cyclone climatology, and that a substantial portion (32 per cent) of the suspended sediment load reaching the delta is delivered by runoff generated by rainfall associated with tropical cyclones. Furthermore, we estimate that the suspended load to the delta has declined by 52.6 ± 10.2 megatonnes over recent years (1981-2005), of which 33.0 ± 7.1 megatonnes is due to a shift in tropical-cyclone climatology. Consequently, tropical cyclones have a key role in controlling the magnitude of, and variability in, transmission of suspended sediment to the coast. It is likely that anthropogenic sediment trapping in upstream reservoirs is a dominant factor in explaining past, and anticipating future, declines in suspended sediment loads reaching the world's major deltas. However, our study shows that changes in tropical-cyclone climatology affect trends in fluvial suspended sediment loads and thus are also key to fully assessing the risk posed to vulnerable coastal systems.

  12. Women take initiative in Vietnam.

    PubMed

    1992-04-01

    Improvements in the health of Vietnamese people is currently being hampered by the lack of medical equipment and medicine. This, despite strong governmental commitment and a vast national health care system that serves the grassroots through a network of village health stations. Vietnam needs strong support to overcome these serious shortages according to Dr Nguyen Thi Ngoc Phuong, Vicechairwoman of the National Assembly of Vietnam. The JOICFP has initiated an Integrated Project (IP) to tackle women's reproductive health issues. The IP supports activities to send supplies and medical equipment from Japan to pilot communes. The Nagano Chapter of the Women's League has been supporting grassroots projects in Vietnam with donations of equipment and funds. Woman play a critical role in development because they account for 50% of the population and work under the double burden of family and employment. In Vietnam, women are a political force that link the government with the grassroots organizations. O the 496 members of Parliament, 88 are women. The IP has greatly improved contraceptive availability. Now condoms, IUDs, the pill are available. Greater access to gynecological examinations are also made possible by the IP. The women of Japan have a lot to offer the women of Vietnam. Their experiences of post World War II allowed them to develop a very effective system of maternal/child health care in this period. The lessons they learned during this time can be of immense value to the health care system of Vietnam.

  13. Mississippi Delta

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The streamers of clouds draped over the Gulf of Mexico in this true-color MODIS image from February 27, 2002, suggest that a cold, dry wind was blowing southward over the United States and began to pick up moisture over the Gulf, causing these strips of clouds. That the clouds didn't pick up until some distance from the coastline allowed MODIS to get a perfect view of the dynamic Gulf Coast environment spanning (left to right) Texas, Louisiana, Mississippi, Alabama, and Florida's Western Panhandle. The Mississippi River runs roughly down the center of the image, and is joined in Louisiana by the Red River coming in from the northwest. Over the past 7000 years, the actual delta, where the main river channel empties into the Gulf, has wandered around what we now think of as the Louisiana coast. Considering all the sediment visible in this image, it's not hard to imagine that the river carries about 2.4 billion kilograms of sediment into the Gulf each year. Deposition of some of this sediment has been building up the current delta, called the Birdfoot Delta, for obvious reasons, for about 700 years. The coastal waters are alive with microscopic organisms called phytoplankton, which contain colorful pigments, including chlorophyll, for harvesting sunlight. Beyond the sediment plume off Louisiana, the waters are very dark, which could indicate that a large amount of chlorophyll is present, absorbing lots of sunlight and causing the water to appear dark. Farther south, the waters appear bright blue, which could be a signature of coccolithophores, which use highly reflective calcium carbonate to build scaly coverings for themselves. The brighter offshore waters could also be caused by a blue-green algae called Trichodesmium, an organism that can not only harness carbon dioxide for photosynthesis, but can also take nitrogen from the air and turn it into a form that can be used by living organisms. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  14. Population growth and natural-resources pressures in the Mekong River Basin.

    PubMed

    Pech, Sokhem; Sunada, Kengo

    2008-05-01

    The Mekong River Basin possesses the region's largest potential water source and related resources, which support ongoing economic development and basin community livelihoods. It is currently witnessing a major demographic transition that is creating both opportunities and challenges. An analysis of the complex relationship between demographic changes and impacts on the natural-resource base confirms that resource exploitation is occurring not only to meet growing domestic needs but also for other vested interests. Population, together with other major drivers, such as institutions, markets, and technology, will have a very strong bearing on the way in which the rich resources of the Mekong River Basin are developed and distributed in the present and future. The Mekong River Basin's rich resources, and the benefits derived from them, are unevenly distributed both in time and geographically. Moreover, since the causes and impacts do not respect political boundaries, the Mekong countries need to jointly develop alternative management strategies to meet projected demands within the sustainable capacity of the Mekong River Basin natural-resource base.

  15. Ecological health monitoring of the Mekong River by using benthic algae in 2003-2004

    NASA Astrophysics Data System (ADS)

    Kunpradid, T.

    2005-05-01

    The monitoring of ecological health of the Mekong River by using benthic algae was carried out from 2003 - 2004. Thirty sampling sites along the Mekong River and its tributaries were selected in Laos, Thailand, Cambodia and Veitnam. In this investigation, the distribution of some species of benthic algae in different environments revealed that there was a significant relationship in the presence of them to the water quality, and these species could be used as a potential biomonitor of water quality in the Mekong River. One hundred and eighty six species of benthic diatoms and 46 species of macroalgae were found. Some dominant species of benthic algae could be used as biomonitors to assess water quality. Hydrodictyon recticulatum and Microspora floccosa and indicated clean-moderate water quality; Audouinella cylindrica, Cladophora glomerata, Achnanthes inflate and Cymbella turgidula indicated moderate water quality; Stigeoclonium flagelliforum, Aulacoseira granulata and Cymbella tumida indicated moderate-polluted water quality and Caloglossa leprieurii, Gomphonema parvulum and Nitzschia clausii indicated polluted water quality. The ecological health assessment of the Mekong River by using the species of benthic algae as biomonitors reveled that in the upstream and tributaries revealed moderate water quality. In contrast, some sites in the lower Mekong showed moderate-polluted to polluted water quality.

  16. The Vietnam Conflict: "America's Best Documented War?"

    ERIC Educational Resources Information Center

    Shaughnessy, C. A.

    1991-01-01

    Discusses problems with military documentation during the Vietnam War. Reports poor record keeping practices, destruction of permanent files, and mislabeled and missing records. Describes the National Archives' Vietnam project that organized and preserved the remaining military records. Concludes that the Vietnam War was better documented than the…

  17. Psychosocial Readjustment of Canadian Vietnam Veterans.

    ERIC Educational Resources Information Center

    Stretch, Robert H.

    1991-01-01

    Examined the psychosocial readjustment of 164 Canadian Vietnam veterans. Found significantly greater rates of posttraumatic stress disorder (PTSD) compared with U.S. Vietnam veterans and evidence of other psychosocial adjustment problems. Suggests that problems are a result, in part, of prolonged isolation from other Vietnam veterans, lack of…

  18. Adaptive Delta Management: cultural aspects of dealing with uncertainty

    NASA Astrophysics Data System (ADS)

    Timmermans, Jos; Haasnoot, Marjolijn; Hermans, Leon; Kwakkel, Jan

    2016-04-01

    Hofstede's (1983) cultural dimensions, of which uncertainty avoidance and long-term orientation are of particular relevance for our analysis. Our conclusions comment on the suitability of approaches in Adaptive Delta Management rooted in different management theories are more suitable for specific delta countries than others. The most striking conclusion is the unsuitability of rational policy analytic approaches for The Netherlands. Although surprising this conclusion finds some support in the process dominated approach taken in the Dutch Delta Program. In addition, the divergence between Vietnam, Bangladesh and Myanmar, all located in South East Asia, is striking. References Hofstede, G. (1983). The cultural relativity of organizational practices and theories. Journal of international business studies, 75-89. Jos Timmermans, Marjolijn Haasnoot, Leon Hermans, Jan Kwakkel, Martine Rutten and Wil Thissen (2015). Adaptive Delta Management: Roots and Branches, IAHR The Hague 2015.

  19. Human exposure to arsenic from drinking water in Vietnam.

    PubMed

    Agusa, Tetsuro; Trang, Pham Thi Kim; Lan, Vi Mai; Anh, Duong Hong; Tanabe, Shinsuke; Viet, Pham Hung; Berg, Michael

    2014-08-01

    Vietnam is an agricultural country with a population of about 88 million, with some 18 million inhabitants living in the Red River Delta in Northern Vietnam. The present study reports the chemical analyses of 68 water and 213 biological (human hair and urine) samples conducted to investigate arsenic contamination in tube well water and human arsenic exposure in four districts (Tu Liem, Dan Phuong, Ly Nhan, and Hoai Duc) in the Red River Delta. Arsenic concentrations in groundwater in these areas were in the range of <1 to 632 μg/L, with severe contamination found in the communities Ly Nhan, Hoai Duc, and Dan Phuong. Arsenic concentrations were markedly lowered in water treated with sand filters, except for groundwater from Hoai Duc. Human hair samples had arsenic levels in the range of 0.07-7.51 μg/g, and among residents exposed to arsenic levels ≥50 μg/L, 64% of them had hair arsenic concentrations higher than 1 μg/g, which is a level that can cause skin lesions. Urinary arsenic concentrations were 4-435 μg/g creatinine. Concentrations of arsenic in hair and urine increased significantly with increasing arsenic content in drinking water, indicating that drinking water is a significant source of arsenic exposure for these residents. The percentage of inorganic arsenic (IA) in urine decreased with age, whereas the opposite trend was observed for monomethylarsonic acid (MMA) in urine. Significant co-interactions of age and arsenic exposure status were also detected for concentrations of arsenic in hair and the sum of IA, MMA, and dimethylarsinic acid (DMA) in urine and %MMA. In summary, this study demonstrates that a considerable proportion of the Vietnamese population is exposed to arsenic levels of chronic toxicity, even if sand filters reduce exposure in many households. Health problems caused by arsenic ingestion through drinking water are increasingly reported in Vietnam.

  20. Some Cenozoic hydrocarbon basins on the continental shelf of Vietnam

    SciTech Connect

    Dien, P.T.

    1994-07-01

    The formation of the East Vietnam Sea basins was related to different geodynamic processes. The pre-Oligocene basement consists of igneous, metamorphic, and metasediment complexes. The Cretaceous-Eocene basement formations are formed by convergence of continents after destruction of the Tethys Ocean. Many Jurassic-Eocene fractured magmatic highs of the Cuulong basin basement constitute important reservoirs that are producing good crude oil. The Paleocene-Eocene formations are characterized by intramountain metamolasses, sometimes interbedded volcanic rocks. Interior structures of the Tertiary basins connect with rifted branches of the widened East Vietnam Sea. Bacbo (Song Hong) basin is predominated by alluvial-rhythmic clastics in high-constructive deltas, which developed on the rifting and sagging structures of the continental branch. Petroleum plays are constituted from Type III source rocks, clastic reservoirs, and local caprocks. Cuulong basin represents sagging structures and is predominated by fine clastics, with tidal-lagoonal fine sandstone and shalestone in high-destructive deltas that are rich in Type II source rocks. The association of the pre-Cenozoic fractured basement reservoirs and the Oligocene-Miocene clastic reservoir sequences with the Oligocene source rocks and the good caprocks is frequently met in petroleum plays of this basin. Nan Conson basin was formed from complicated structures that are related to spreading of the oceanic branch. This basin is characterized by Oligocene epicontinental fine clastics and Miocene marine carbonates that are rich in Types I, II, and III organic matter. There are both pre-Cenozoic fractured basement reservoirs, Miocene buildup carbonate reservoir rocks and Oligocene-Miocene clastic reservoir sequences, in this basin. Pliocene-Quaternary sediments are sand and mud carbonates in the shelf facies of the East Vietnam Sea back-arc basin. Their great thickness provides good conditions for maturation and trapping.

  1. Mississippi Delta

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Mississippi River delta teems with sediment deposited by the river as it flows into the Gulf of Mexico in this true-color image captured by MODIS on October 15, 2001. The sediment, which is marked by brown swirls in the Gulf, provides nutrients for the bloom of phytoplankton visible as blue-green swirls off the coastline. In the high-resolution image the city of Memphis can be seen in the southwest corner of Tennessee, which is just to left of center at the top of the image. The brown coloration that encompasses Memphis and either side of the river, as flows north to south along the left side of the image, is the river's flood plain. Also visible, in the upper-right hand corner of the image is the southern end of the Appalachian Mountains.

  2. Epidemiology of Strongyloides stercoralis on Mekong islands in southern Laos.

    PubMed

    Vonghachack, Youthanavanh; Sayasone, Somphou; Bouakhasith, Dalouny; Taisayavong, Keoka; Akkavong, Kongsap; Odermatt, Peter

    2015-01-01

    Strongyloides stercoralis is a neglected helminth infection potentially that can lead to systemic infection in immunocompromised individuals. In Lao People's Democratic Republic (Lao PDR, Laos), information on S. stercoralis infection is scarce. We assessed S. stercoralis infection and associated risk factors and symptoms on the Mekong islands in Southern Laos. Baermann and Kato-Katz techniques were performed on two stool samples from each individual to detect S. stercoralis larvae and concomitant helminth infections. Among 729 individuals, 41.0% were infected with S. stercoralis. Men were at higher risk than women (OR 1.97, 95% CI 1.45-2.67). Urticaria and body itching was associated with S. stercoralis infection (OR 2.4, 95% CI 1.42-4.05). Infection with Opisthorchis viverrini (72.2%), Schistosoma mekongi (12.8%), and hookworm (56.1%) were very common. Few infections with Trichuris trichiura (3.3%), Ascaris lumbricoides (0.3%) and Taenia spp. (0.3%) were detected. The majority of helminth infections were of light intensity, with prevalences of 80.4%, 92.9%, 64.5%, 100% and 100%, for O. viverrini, hookworm, S. mekongi, T. trichiura and A. lumbricoides, respectively. Nevertheless, heavy infection intensities were observed for O. viverrini (1.0%), S. mekongi (14.0%) and hookworm (2.9%). S. stercoralis is highly endemic on the islands of Khong district, Champasack province, Southern Laos. The national helminth control programme should take action to control this helminth infection.

  3. Opisthorchis viverrini infections and associated risk factors in a lowland area of Binh Dinh Province, Central Vietnam.

    PubMed

    Dao, Thanh Thi Ha; Bui, Tuan Van; Abatih, Emmanuel Nji; Gabriël, Sarah; Nguyen, Thanh Thi Giang; Huynh, Quang Hong; Nguyen, Chuong Van; Dorny, Pierre

    2016-05-01

    Opisthorchiasis caused by Opisthorchis viverrini is a major public health problem in the Mekong Basin in South East Asia. It is associated with cholangiocarcinoma, a fatal cancer of the bile duct, which is very common in some areas of Thailand and Lao PDR. Although there is evidence of opisthorchiasis in the central and Southern provinces of Vietnam, data are scarce and Vietnam is often not considered an opisthorchiasis endemic area in the international literature. We conducted a cross-sectional survey in June 2015 in a lowland rural area of Binh Dinh Province in Central Vietnam to investigate the apparent prevalence of O. viverrini infection in the population and the associated risk factors. A total of 254 stool samples were collected and examined by the Kato Katz method. Consenting people shedding Opisthorchis-like eggs with their stools were treated with praziquantel and MgSO4 and adult worms were collected from stools for morphological and molecular identifications. Risk factors were studied with a structured questionnaire and the association with infection was evaluated by univariate and multivariate Firth's logistic regression analysis. The apparent prevalence in the investigated population determined by stool examination was 11.4% (CI: 8-16%). Infection with O. viverrini was confirmed in all 11 individuals consenting to receive praziquantel treatment and subsequent worm recovery from stools. The mean number of worms recovered after treatment/purgation was 14.5 (range 2-44). Male gender and the consumption of dishes prepared from raw small wild-caught freshwater fish (Carassius auratus) were found to be significant risk factors associated with opisthorchiasis in the area. These findings confirm the presence of O. viverrini infection in Central Vietnam related to the consumption of raw fish dishes. Awareness campaigns and control programs should be implemented in the region to combat this potentially fatal fluke infection.

  4. Mahseers genera Tor and Neolissochilus (Teleostei: Cyprinidae) from southern Vietnam.

    PubMed

    Hoàng, Huy Đức; Phạm, Hùng Mạnh; Durand, Jean-Dominique; Trần, Ngân Trọng; Phan, Phúc Đình

    2015-08-25

    Two new species and two new basin records of mahseers in the genera Tor and Neolissochilus are described from the upper Krong No and middle Đồng Nai drainages of the Langbiang Plateau in southern Vietnam. These new species and new records are known from streams and rivers in montane mixed pine and evergreen forests between 140 and 1112 m. Their populations are isolated in the Sre Pok River of the Mekong basin, the middle of the Đồng Nai basin, and the An Lão River. Both new species are differentiated from their congeners by a combination of the following characters: 23-24 lateral scales, 9-10 predorsal scales, 2/7 or 1/8 pelvic-fin rays, mouth position, median lobe of lower lip, rostral hood, colour in life and by divergent mitochondrial DNA. Tor mekongensis sp. nov. is differentiated from Tor dongnaiensis sp. nov. by the number of transverse scale rows (3/1/2 vs. 4/1/2), number of pelvic-fin rays (2/7 vs. 1/8), a blunt rostral hood vs. pointed, caudal-fin lobes that are equal vs. unequal, and by mitochondrial DNA (0.7% sequence divergence). Molecular evidence identifies both species as members of the genus Tor and distinct from all congeners sampled (uncorrected sequence divergences >1.9% for all Tor species for which homologous COI sequences are available). Tor sinensis is recorded in the Krong No and the Sre Pok rivers, further south of its known distribution. Polymorphism is described in Neolissochilus stracheyi with a Tor-like morph and a Neolissochilus-like morph.

  5. Human tapeworms in north Vietnam.

    PubMed

    Somers, Raf; Dorny, Pierre; Geysen, Dirk; Nguyen, Lan Anh; Thach, Dang Cam; Vercruysse, Jozef; Nguyen, Viet Khong

    2007-03-01

    Sixty-five Taenia samples were collected from patients in a referral hospital in Hanoi, north Vietnam, for species identification by morphological and molecular techniques. PCR-RFLP of a mitochondrial 12S rDNA fragment, developed for this study, allowed direct differentiation between all Taenia spp., overcoming the disadvantages of classical morphological examination, which failed on disintegrated samples. Taenia saginata asiatica was the most common species (55.4%) followed by T. saginata (38.5%) and T. solium (6.2%). This report demonstrates the complexity of the epidemiology of Taenia spp. in Vietnam and the need for further work to reveal transmission patterns of these species.

  6. Deviance and resistance: Malaria elimination in the greater Mekong subregion.

    PubMed

    Lyttleton, Chris

    2016-02-01

    Malaria elimination rather than control is increasingly globally endorsed, requiring new approaches wherein success is not measured by timely treatment of presenting cases but eradicating all presence of infection. This shift has gained urgency as resistance to artemisinin-combination therapies spreads in the Greater Mekong Sub-region (GMS) posing a threat to global health security. In the GMS, endemic malaria persists in forested border areas and elimination will require calibrated approaches to remove remaining pockets of residual infection. A new public health strategy called 'positive deviance' is being used to improve health promotion and community outreach in some of these zones. However, outbreaks sparked by alternative understandings of appropriate behaviour expose the unpredictable nature of 'border malaria' and difficulties eradication faces. Using a recent spike in infections allegedly linked to luxury timber trade in Thai borderlands, this article suggests that opportunities for market engagement can cause people to see 'deviance' as a means to material advancement in ways that increase disease vulnerability. A malaria outbreak in Ubon Ratchathani was investigated during two-week field-visit in November 2014 as part of longer project researching border malaria in Thai provinces. Qualitative data were collected in four villages in Ubon's three most-affected districts. Discussions with villagers focused primarily on changing livelihoods, experience with malaria, and rosewood cutting. Informants included ten men and two women who had recently overnighted in the nearby forest. Data from health officials and villagers are used to frame Ubon's rise in malaria transmission within moral and behavioural responses to expanding commodity supply-chains. The article argues that elimination strategies in the GMS must contend with volatile outbreaks among border populations wherein 'infectiousness' and 'resistance' are not simply pathogen characteristics but also

  7. Body size–trophic position relationships among fishes of the lower Mekong basin

    PubMed Central

    Montaña, Carmen G.; Winemiller, Kirk O.

    2017-01-01

    Body size is frequently claimed to be a major determinant of animal trophic interactions, yet few studies have explored relationships between body size and trophic interactions in rivers, especially within the tropics. We examined relationships between body size and trophic position (TP) within fish assemblages in four lowland rivers of the Lower Mekong Basin in Cambodia. Stable isotope analysis (based on δ15N) was used to estimate TP of common fish species in each river, and species were classified according to occupation of benthic versus pelagic habitats and major feeding guilds. Regression analysis yielded strong correlations between body size and TP among fishes from the Sesan and Sreprok rivers, but not those from the Mekong and Sekong rivers. The Mekong fish assemblage had higher average TP compared with those of other rivers. The relationship between body size and TP was positive and significantly correlated for piscivores and omnivores, but not for detritivores and insectivores. The body size–TP relationship did not differ between pelagic and benthic fishes. Body size significantly predicted TP within the orders Siluriformes and Perciformes, but not for Cypriniformes, the most species-rich and ecologically diverse order in the Lower Mekong River. We conclude that for species-rich, tropical fish assemblages with many detritivores and invertivores, body size would not be an appropriate surrogate for TP in food web models and other ecological applications. PMID:28280563

  8. Body size-trophic position relationships among fishes of the lower Mekong basin.

    PubMed

    Ou, Chouly; Montaña, Carmen G; Winemiller, Kirk O

    2017-01-01

    Body size is frequently claimed to be a major determinant of animal trophic interactions, yet few studies have explored relationships between body size and trophic interactions in rivers, especially within the tropics. We examined relationships between body size and trophic position (TP) within fish assemblages in four lowland rivers of the Lower Mekong Basin in Cambodia. Stable isotope analysis (based on δ(15)N) was used to estimate TP of common fish species in each river, and species were classified according to occupation of benthic versus pelagic habitats and major feeding guilds. Regression analysis yielded strong correlations between body size and TP among fishes from the Sesan and Sreprok rivers, but not those from the Mekong and Sekong rivers. The Mekong fish assemblage had higher average TP compared with those of other rivers. The relationship between body size and TP was positive and significantly correlated for piscivores and omnivores, but not for detritivores and insectivores. The body size-TP relationship did not differ between pelagic and benthic fishes. Body size significantly predicted TP within the orders Siluriformes and Perciformes, but not for Cypriniformes, the most species-rich and ecologically diverse order in the Lower Mekong River. We conclude that for species-rich, tropical fish assemblages with many detritivores and invertivores, body size would not be an appropriate surrogate for TP in food web models and other ecological applications.

  9. From Combat to Legacies: Novels of the Vietnam War.

    ERIC Educational Resources Information Center

    Johannessen, Larry R.

    1995-01-01

    Discusses novels of the Vietnam War, their usefulness, and the interest they hold for students. Considers four categories of Vietnam novels: the Vietnam experience, the war at home, the refugee experience, and the war's effect on the next generation. (SR)

  10. The Delta 2 launcher

    NASA Astrophysics Data System (ADS)

    Ousley, Gilbert W., Sr.

    1991-12-01

    The utilization of the Delta 2 as the vehicle for launching Aristoteles into its near Sun synchronous orbit is addressed. Delta is NASA's most reliable launch vehicle and is well suited for placing the present Aristoteles spacecraft into a 400 m circular orbit. A summary of some of the Delta 2 flight parameters is presented. Diagrams of a typical Delta 2 two stage separation are included along with statistics on delta reliability and launch plans.

  11. Vietnam recommended dietary allowances 2007.

    PubMed

    Khan, Nguyen Cong; Hoan, Pham Van

    2008-01-01

    It has been well acknowledged that Vietnam is undergoing a nutrition transition. With a rapid change in the country's reform and economic growth, food supply at the macronutrient level has improved. Changes of the Vietnamese diet include significantly more foods of animal origin, and an increase of fat/oils, and ripe fruits. Consequently, nutritional problems in Vietnam now include not only malnutrition but also overweight/obesity, metabolic syndrome and other chronic diseases related to nutrition and lifestyles. The recognition of these shifts, which is also associated with morbidity and mortality, was a major factor in the need to review and update the Recommended Dietary Allowances (RDA) for the Vietnamese population. This revised RDA established an important science-based tool for evaluation of nutrition adequacy, for teaching, and for scientific communications within Vietnam. It is expected that the 2007 Vietnam RDA and its conversion to food-based dietary guidelines will facilitate education to the public, as well as the policy implementation of programs for prevention of non-communicable chronic diseases and addressing the double burden of both under and over nutrition.

  12. Agro-Environmental Determinants of Avian Influenza Circulation: A Multisite Study in Thailand, Vietnam and Madagascar

    PubMed Central

    Paul, Mathilde C.; Gilbert, Marius; Desvaux, Stéphanie; Rasamoelina Andriamanivo, Harena; Peyre, Marisa; Khong, Nguyen Viet; Thanapongtharm, Weerapong; Chevalier, Véronique

    2014-01-01

    Outbreaks of highly pathogenic avian influenza have occurred and have been studied in a variety of ecological systems. However, differences in the spatial resolution, geographical extent, units of analysis and risk factors examined in these studies prevent their quantitative comparison. This study aimed to develop a high-resolution, comparative study of a common set of agro-environmental determinants of avian influenza viruses (AIV) in domestic poultry in four different environments: (1) lower-Northern Thailand, where H5N1 circulated in 2004–2005, (2) the Red River Delta in Vietnam, where H5N1 is circulating widely, (3) the Vietnam highlands, where sporadic H5N1 outbreaks have occurred, and (4) the Lake Alaotra region in Madagascar, which features remarkable similarities with Asian agro-ecosystems and where low pathogenic avian influenza viruses have been found. We analyzed H5N1 outbreak data in Thailand in parallel with serological data collected on the H5 subtype in Vietnam and on low pathogenic AIV in Madagascar. Several agro-environmental covariates were examined: poultry densities, landscape dominated by rice cultivation, proximity to a water body or major road, and human population density. Relationships between covariates and AIV circulation were explored using spatial generalized linear models. We found that AIV prevalence was negatively associated with distance to the closest water body in the Red River Delta, Vietnam highlands and Madagascar. We also found a positive association between AIV and duck density in the Vietnam highlands and Thailand, and with rice landscapes in Thailand and Madagascar. Our findings confirm the important role of wetlands-rice-ducks ecosystems in the epidemiology of AI in diverse settings. Variables influencing circulation of the H5 subtype in Southeast Asia played a similar role for low pathogenic AIV in Madagascar, indicating that this area may be at risk if a highly virulent strain is introduced. PMID:25029441

  13. Agro-environmental determinants of avian influenza circulation: a multisite study in Thailand, Vietnam and Madagascar.

    PubMed

    Paul, Mathilde C; Gilbert, Marius; Desvaux, Stéphanie; Andriamanivo, Harena Rasamoelina; Peyre, Marisa; Khong, Nguyen Viet; Thanapongtharm, Weerapong; Chevalier, Véronique

    2014-01-01

    Outbreaks of highly pathogenic avian influenza have occurred and have been studied in a variety of ecological systems. However, differences in the spatial resolution, geographical extent, units of analysis and risk factors examined in these studies prevent their quantitative comparison. This study aimed to develop a high-resolution, comparative study of a common set of agro-environmental determinants of avian influenza viruses (AIV) in domestic poultry in four different environments: (1) lower-Northern Thailand, where H5N1 circulated in 2004-2005, (2) the Red River Delta in Vietnam, where H5N1 is circulating widely, (3) the Vietnam highlands, where sporadic H5N1 outbreaks have occurred, and (4) the Lake Alaotra region in Madagascar, which features remarkable similarities with Asian agro-ecosystems and where low pathogenic avian influenza viruses have been found. We analyzed H5N1 outbreak data in Thailand in parallel with serological data collected on the H5 subtype in Vietnam and on low pathogenic AIV in Madagascar. Several agro-environmental covariates were examined: poultry densities, landscape dominated by rice cultivation, proximity to a water body or major road, and human population density. Relationships between covariates and AIV circulation were explored using spatial generalized linear models. We found that AIV prevalence was negatively associated with distance to the closest water body in the Red River Delta, Vietnam highlands and Madagascar. We also found a positive association between AIV and duck density in the Vietnam highlands and Thailand, and with rice landscapes in Thailand and Madagascar. Our findings confirm the important role of wetlands-rice-ducks ecosystems in the epidemiology of AI in diverse settings. Variables influencing circulation of the H5 subtype in Southeast Asia played a similar role for low pathogenic AIV in Madagascar, indicating that this area may be at risk if a highly virulent strain is introduced.

  14. Stratigraphy and Holocene evolution of the mud-dominated Chao Phraya delta, Thailand

    NASA Astrophysics Data System (ADS)

    Tanabe, Susumu; Saito, Yoshiki; Sato, Yoshio; Suzuki, Yuichiro; Sinsakul, Sin; Tiyapairach, Suwat; Chaimanee, Niran

    2003-04-01

    The central plain of Thailand was formed over the last 8-7 kyr mainly by the deltaic processes of two major rivers, the Chao Phraya and the Mae Klong. The delta plain is the third largest delta plain in Southeast Asia after that of the Mekong and the Irrawaddy. On the basis of sedimentological and paleontological analyses of samples from three boreholes and an open-pit survey, the evolution of the delta was clarified with high-resolution 14C dating. After the maximum transgression at between 8 and 7 cal kyr BP, the delta system migrated southward into the paleo-Gulf of Ayutthaya. A large mud shoal (the Sananivate Mud Shoal) formed near the mouth of the paleo-gulf between 7 and 3 cal kyr BP and facilitated its infilling. As a result, the delta has prograded rapidly particularly during the last 2 kyr. Deltaic sediment volume for the last 7.5±0.5 kyr shows that the average rate of sedimentation was 23.1±3.6 million t/yr, which is nearly the same as the present total sediment discharge from both rivers. The comparatively wide delta plain relative to sediment discharge resulted from the stable sea level, the shallow paleo-gulf acting as a receiving basin, and effective sediment trapping because of the mud shoal.

  15. The United States and Vietnam Relationship: Benefits and Challenges for Vietnam

    DTIC Science & Technology

    2016-06-10

    Major Exports to Vietnam aircraft, mining equipment, electronic machinery, steel wire , raw cotton, plastics Source: Mark E. Manyin, The Vietnam...cooperation, national interests are always calculated by countries. Common interests are one of many factors drawing countries together. Vietnam and the U.S...

  16. Mid to late Holocene sea-level reconstruction of Southeast Vietnam using beachrock and beach-ridge deposits

    NASA Astrophysics Data System (ADS)

    Stattegger, Karl; Tjallingii, Rik; Saito, Yoshiki; Michelli, Maximiliano; Trung Thanh, Nguyen; Wetzel, Andreas

    2013-11-01

    Beachrocks, beach ridge, washover and backshore deposits along the tectonically stable south-eastern Vietnamese coast document Holocene sea level changes. In combination with data from the final marine flooding phase of the incised Mekong River valley, the sea-level history of South Vietnam could be reconstructed for the last 8000 years. Connecting saltmarsh, mangrove and beachrock deposits the record covers the last phase of deglacial sea-level rise from - 5 to + 1.4 m between 8.1 to 6.4 ka. The rates of sea-level rise decreased sharply after the rapid early Holocene rise and stabilized at a rate of 4.5 mm/year between 8.0 and 6.9 ka. Southeast Vietnam beachrocks reveal that the mid-Holocene sea-level highstand slightly above + 1.4 m was reached between 6.7 and 5.0 ka, with a peak value close to + 1.5 m around 6.0 ka. This highstand is further limited by a backshore and beachridge deposit that marks the maximum springtide sea-level just below the base of the overlying beach ridge. After 5.0 ka sea level dropped below + 1.4 m and fell almost linearly at a rate of 0.24 mm/year until 0.63 ka and + 0.2 m as evidenced by the youngest beachrocks.

  17. An analysis of health system resources in relation to pandemic response capacity in the Greater Mekong Subregion

    PubMed Central

    2012-01-01

    Background There is increasing perception that countries cannot work in isolation to militate against the threat of pandemic influenza. In the Greater Mekong Subregion (GMS) of Asia, high socio-economic diversity and fertile conditions for the emergence and spread of infectious diseases underscore the importance of transnational cooperation. Investigation of healthcare resource distribution and inequalities can help determine the need for, and inform decisions regarding, resource sharing and mobilisation. Methods We collected data on healthcare resources deemed important for responding to pandemic influenza through surveys of hospitals and district health offices across four countries of the GMS (Cambodia, Lao PDR, Thailand, Vietnam). Focusing on four key resource types (oseltamivir, hospital beds, ventilators, and health workers), we mapped and analysed resource distributions at province level to identify relative shortages, mismatches, and clustering of resources. We analysed inequalities in resource distribution using the Gini coefficient and Theil index. Results Three quarters of the Cambodian population and two thirds of the Laotian population live in relatively underserved provinces (those with resource densities in the lowest quintile across the region) in relation to health workers, ventilators, and hospital beds. More than a quarter of the Thai population is relatively underserved for health workers and oseltamivir. Approximately one fifth of the Vietnamese population is underserved for beds and ventilators. All Cambodian provinces are underserved for at least one resource. In Lao PDR, 11 percent of the population is underserved by all four resource items. Of the four resources, ventilators and oseltamivir were most unequally distributed. Cambodia generally showed higher levels of inequalities in resource distribution compared to other countries. Decomposition of the Theil index suggests that inequalities result principally from differences within, rather

  18. Health equity and migrants in the Greater Mekong Subregion

    PubMed Central

    McMichael, Celia; Healy, Judith

    2017-01-01

    ABSTRACT Background: Migrant health is receiving increasing international attention, reflecting recognition of the health inequities experienced among many migrant populations and the need for health systems to adapt to diverse migrant populations. In the Greater Mekong Subregion (GMS) there is increasing migration associated with uneven economic integration and growth, socio-economic vulnerabilities, and disparities between countries. There has been limited progress, however, in improving migrant access to health services in the Subregion. This paper examines the health needs, access barriers, and policy responses to cross-border migrants in five GMS countries. Methods: A review of published literature and research was conducted on migrant health and health service access in Cambodia, Lao People’s Democratic Republic, Myanmar, Thailand, and Viet Nam, as well as analysis of current migration trends and universal health coverage (UHC) indicators in the Subregion. The review included different migrant types: i.e. migrant workers, irregular migrants, victims of trafficking, refugees and asylum seekers, and casual cross-border migrants. Results: There is substantial diversity in the capacity of GMS health systems to address migrant populations. Thailand has sought to enhance migrant health coverage, including development of migrant health policies/programs, bilateral migrant worker agreements, and migrant health insurance schemes; Viet Nam provides health protection for emigrant workers. Overall, however, access to good quality health care remains weak for many citizens in GMS countries let alone migrants. Migrant workers – and irregular migrants in particular – face elevated health risks yet are not adequately covered and incur high out-of-pocket (OOP) payments for health services. Conclusions: UHC implies equity: UHC is only achieved when everyone has the opportunity to access and use good-quality health care. Efforts to achieve UHC in the GMS require

  19. delta-Hexachlorocyclohexane (delta-HCH)

    Integrated Risk Information System (IRIS)

    delta - Hexachlorocyclohexane ( delta - HCH ) ; CASRN 319 - 86 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Ass

  20. Delta agent (Hepatitis D)

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/000216.htm Delta agent (Hepatitis D) To use the sharing features on this page, please enable JavaScript. Delta agent is a type of virus called hepatitis ...

  1. An Analysis of Historical Impacts of Water Resources Development on Water Levels of the Mekong River (Invited)

    NASA Astrophysics Data System (ADS)

    Cochrane, T. A.; Arias, M. E.; Piman, T.

    2013-12-01

    The rapid rate of water resources development in the Mekong basin of Southeast Asia is a cause for concern due to potential impacts on highly valued fisheries and natural ecosystems. Historical water levels of the Mekong were analyzed by comparing pre and post 1991 daily data of 6 stations along the mainstream from Chiang Sean, in northern Lao PDR and Thailand, to Stung Treng, in Cambodia, and the Pre Kdam station near the Tonle Sap Lake in the lower Mekong floodplain using the Indicators of Hydrological Alteration (IHA) software. The year 1991 marks a turning point in the rate of development in the basin, with the start of development of mainstream dams in the upper Mekong and accelerated hydropower and irrigation development in key tributaries. Observed changes in water level patterns along the Mekong were linked to temporal and spatial water resources development from 1960 to 2010. Variations in climate were accounted for and are important, but they were not observed to be the main causes of changes in key hydrological indicators related to ecosystem productivity. The development of mainstream dams in the upper Mekong basin in the post 1991 period resulted in a significant change of seasonal water levels, raise rates, fall rates, and the number of water level fluctuations at Chiang Sean. This effect diminishes downstream until it becomes negligible at the Mukdahan monitoring station in Thailand, which represents a drainage area of over 50% of the total Mekong Basin. Further downstream at Pakse station in Southern Lao PDR, changes in hydrological indicators post 1991 were observed to be significant again, which can be directly attributed to water resource development in the Chi and Mun River basins in Northeastern Thailand. A reduction of 23% and 11% in water level raising rates and fall rates, respectively at Prek Kdam, provides clear evidence of a diminished flood pulse of the Tonle Sap Lake in the post 1991 period. Given the observed water level alterations

  2. Neurology in the Vietnam War.

    PubMed

    Gunderson, Carl H; Daroff, Robert B

    2016-01-01

    Between December 1965 and December 1971, the United States maintained armed forces in Vietnam never less than 180,000 men and women in support of the war. At one time, this commitment exceeded half a million soldiers, sailors, and airmen from both the United States and its allies. Such forces required an extensive medical presence, including 19 neurologists. All but two of the neurologists had been drafted for a 2-year tour of duty after deferment for residency training. They were assigned to Vietnam for one of those 2 years in two Army Medical Units and one Air Force facility providing neurological care for American and allied forces, as well as many civilians. Their practice included exposure to unfamiliar disorders including cerebral malaria, Japanese B encephalitis, sleep deprivation seizures, and toxic encephalitis caused by injection or inhalation of C-4 explosive. They and neurologists at facilities in the United States published studies on all of these entities both during and after the war. These publications spawned the Defense and Veterans Head Injury Study, which was conceived during the Korean War and continues today as the Defense and Veterans Head Injury Center. It initially focused on post-traumatic epilepsy and later on all effects of brain injury. The Agent Orange controversy arose after the war; during the war, it was not perceived as a threat by medical personnel. Although soldiers in previous wars had developed serious psychological impairments, post-traumatic stress disorder was formally recognized in the servicemen returning from Vietnam.

  3. Fish Migration, Dams, and Loss of Ecosystem Services in the Mekong Basin

    SciTech Connect

    Dugan, Patrick J.; Barlow, Chris; Agostinho, Angelo A.; Baran, Eric; Cada, Glenn F; Chen, Daqing; Cowx, Ian G.; Ferguson, John W.; Jutagate, Tuantong; Mallen-Cooper, Martin; Marmulla, Gerd; Nestler, John; Petrere, Miquel; Winemiller, Kirk O.

    2010-06-01

    The past decade has seen increased international recognition of the importance of the services provided by natural ecosystems. It is unclear however whether such international awareness will lead to improved environmental management in many regions. We explore this issue by examining the specific case of fish migration and dams on the Mekong river. We determine that dams on the Mekong mainstem and major tributaries will have a major impact on the basin's fisheries and the people who depend upon them for food and income. We find no evidence that current moves towards dam construction will stop, and consider two scenarios for the future of the fisheries and other ecosystems of the basin. We conclude that major investment is required in innovative technology to reduce the loss of ecosystem services, and alternative livelihood strategies to cope with the losses that do occur

  4. Trading-off fish biodiversity, food security, and hydropower in the Mekong River Basin.

    PubMed

    Ziv, Guy; Baran, Eric; Nam, So; Rodríguez-Iturbe, Ignacio; Levin, Simon A

    2012-04-10

    The Mekong River Basin, site of the biggest inland fishery in the world, is undergoing massive hydropower development. Planned dams will block critical fish migration routes between the river's downstream floodplains and upstream tributaries. Here we estimate fish biomass and biodiversity losses in numerous damming scenarios using a simple ecological model of fish migration. Our framework allows detailing trade-offs between dam locations, power production, and impacts on fish resources. We find that the completion of 78 dams on tributaries, which have not previously been subject to strategic analysis, would have catastrophic impacts on fish productivity and biodiversity. Our results argue for reassessment of several dams planned, and call for a new regional agreement on tributary development of the Mekong River Basin.

  5. Vietnam Veteran Levels of Combat: Perceived and Actual Violence.

    ERIC Educational Resources Information Center

    Calvert, William; Hutchinson, Roger L.

    The purpose of this study was to investigate whether or not a relationship exists between levels of combat experienced by Vietnam veterans and later perceptions of violence, violent attitudes, or violent behavior. Comparison groups included: (1) heavy combat Vietnam veterans; (2) light combat Vietnam veterans; (3) no combat Vietnam veterans; and…

  6. Vietnam: The Political Economy of Education in a "Socialist" Periphery

    ERIC Educational Resources Information Center

    London, Jonathan D.

    2006-01-01

    In this article I examine historic changes in the goals, conduct and outcomes of education policies in Vietnam from the 1940s to the present, under the Communist Party of Vietnam. Recent studies of Vietnam's education system centre on econometric and demographic analysis of education data dating back to the early 1990s, when Vietnam began an…

  7. 77 FR 20273 - Vietnam Veterans Day

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-03

    ... April 3, 2012 Part IV The President Proclamation 8789--Vietnam Veterans Day Memorandum of March 30, 2012... ] Proclamation 8789 of March 29, 2012 Vietnam Veterans Day By the President of the United States of America A..., day after day to preserve the liberties we hold dear. From Ia Drang to Hue, they won every...

  8. "Achilles in Vietnam" and the Humanities Classroom.

    ERIC Educational Resources Information Center

    Walter, James A.

    This paper discusses the book "Achilles in Vietnam" (Jonathan Shay) in relation to Homer's "Iliad" and the need for society to accept the consequences of veterans' experiences. Classical allusions to the epic are incorporated into the study and U.S. experience of the Vietnam War. The paper advocates student "ownership" of literature study and…

  9. Musical Images of the Vietnam War.

    ERIC Educational Resources Information Center

    Chilcoat, George W.; Vocke, David E.

    Teaching the Vietnam War in high school history courses is a challenge to the instructor, and study that relies only on textbooks may neglect the controversy surrounding the War and the issues that faced the nation. This paper discusses how to use songs about the Vietnam War as an instructional tool to investigate the role of songs during the War…

  10. Educational Reform and Teacher Education in Vietnam

    ERIC Educational Resources Information Center

    Hamano, Takashi

    2008-01-01

    This paper examines the current state and a challenge faced by teachers and teacher education in Vietnam, and analyzes international aid projects providing support to teacher education there. It is necessary to grasp changes in teacher education in Vietnam in the context of the current comprehensive reform of education, which has been greatly…

  11. Teaching the Vietnam War: A Sociological Approach.

    ERIC Educational Resources Information Center

    Starr, Jerold M.

    1995-01-01

    Maintains that, because of its importance in modern U.S. history, over 300 college courses are taught on the Vietnam War. Asserts that studying the war helps students develop critical thinking skills needed for citizenship. Describes the texts, formats, and assignments used in a college sociology course on the Vietnam War. (CFR)

  12. Vietnam and CORDS: Interagency Lessons for Iraq

    DTIC Science & Technology

    2008-11-24

    Vietnam War for Dummies (New York: Wiley Publishing, 2003), 237-239. 18 w f ed y zations w y ordination suffered accordingly. Sc...Army War College, 2006. Frankum, Ronald B. and Maxner, Stephan F. The Vietnam War for Dummies . New York : Wiley Publishing, 2003. Galula, David

  13. Institutional Autonomy for Higher Education in Vietnam

    ERIC Educational Resources Information Center

    Hayden, Martin; Thiep, Lam Quang

    2007-01-01

    Vietnam has recently accepted the need for a comprehensive transformation of its higher education system. In 2005, the Ministry of Education and Training developed a Higher Education Reform Agenda (HERA), a blueprint for reform of the system by 2020. The Government of Vietnam recently approved the main elements of the Agenda, including a proposal…

  14. Water level response to hydropower development in the upper Mekong River.

    PubMed

    Li, Shaojuan; He, Daming

    2008-05-01

    Environmental changes and their transboundary influences on the Mekong watercourse system have been an international research focus in recent years, but the opinions and results related to the impacts of upper Mekong River dams are quite different. In this paper, based on the records of water levels from 1960 to 2003 at three mainstream sites in the upper Mekong River, a quantitative examination has been undertaken into characteristics of the mainstream water-level process at multiple timescales and its response to cascade development. The major results are: i) Annual mean, wet period mean, and the mean water levels during the period between March and April (PBMA period) exhibit a significant increasing trend at Jiuzhou and Yunjinghong sites, which are influenced by large-scale factors such as climate change and solar activity. ii) The interdecadal and interannual variations of annual mean, annual maximum, and wet period mean water levels at three sites show similar features during the dam construction period. iii) The interdecadal variations of PBMA period water level show a gradual increase at Gajiu and Yunjinghong sites but a falling trend at Jiuzhou; these trends confirm that there is some regulation on the flow in the dry season caused by the two existing dams. iv) The downstream effects of the present dams on water levels are very limited at the annual mean and wet season mean levels, not apparent at the monthly and yearly timescales, and relatively significant at daily and hourly timescales.

  15. Impact of the Mekong River flow alteration on the Tonle Sap flood pulse.

    PubMed

    Kummu, Matti; Sarkkula, Juha

    2008-05-01

    Rapid development in the upper reaches of the Mekong River, in the form of construction of large hydropower dams and reservoirs, large irrigation schemes, and rapid urban development, is putting water resources under stress. Recent studies have concluded that these developments will lead to flow alterations in the Mekong River. These flow alterations would threaten the sensitive ecosystems downstream, particularly Tonle Sap River, Tonle Sap Lake, its floodplain, and its gallery forest and protected areas, by changing the flood-pulse system of the lake. This article estimates the changes in parameters of the Tonle Sap flood pulse due to the aforementioned flow alterations. The impacts on the flooded area and loss of gallery forest and protected areas were analyzed using geographic information system-based methods. Relatively small rises in the dry-season lake water level would permanently inundate disproportionately large areas of floodplain, rendering it inaccessible to floodplain vegetation and eroding the productivity basis of the ecosystem. It is highly important to maintain the natural hydrological pattern of the Mekong River, particularly the dry-season water levels, to preserve Tonle Sap Lake's ecosystem productivity.

  16. Future changes in Mekong River hydrology: impact of climate change and reservoir operation on discharge

    NASA Astrophysics Data System (ADS)

    Lauri, H.; de Moel, H.; Ward, P. J.; Räsänen, T. A.; Keskinen, M.; Kummu, M.

    2012-05-01

    The transboundary Mekong River is facing two on-going changes that are estimated to significantly impact its hydrology and the characteristics of its exceptional flood pulse. The rapid economic development of the riparian countries has led to massive plans for hydropower construction, and the projected climate change is expected to alter the monsoon patterns and increase temperature in the basin. The aim of this study is to assess the cumulative impact of these factors on the hydrology of the Mekong within next 20-30 yr. We downscaled output of five General Circulation Models (GCMs) that were found to perform well in the Mekong region. For the simulation of reservoir operation, we used an optimisation approach to estimate the operation of multiple reservoirs, including both existing and planned hydropower reservoirs. For hydrological assessment, we used a distributed hydrological model, VMod, with a grid resolution of 5 km × 5 km. In terms of climate change's impact to hydrology, we found a high variation in the discharge results depending on which of the GCMs is used as input. The simulated change in discharge at Kratie (Cambodia) between the baseline (1982-1992) and projected time period (2032-2042) ranges from -11% to +15% for the wet season and -10% to +13% for the dry season. Our analysis also shows that the changes in discharge due to planned reservoir operations are clearly larger than those simulated due to climate change: 25-160% higher dry season flows and 5-24% lower flood peaks in Kratie. The projected cumulative impacts follow rather closely the reservoir operation impacts, with an envelope around them induced by the different GCMs. Our results thus indicate that within the coming 20-30 yr, the operation of planned hydropower reservoirs is likely to have a larger impact on the Mekong hydrograph than the impacts of climate change, particularly during the dry season. On the other hand, climate change will increase the uncertainty of the estimated

  17. Future changes in Mekong River hydrology: impact of climate change and reservoir operation on discharge

    NASA Astrophysics Data System (ADS)

    Lauri, H.; de Moel, H.; Ward, P. J.; Räsänen, T. A.; Keskinen, M.; Kummu, M.

    2012-12-01

    The transboundary Mekong River is facing two ongoing changes that are expected to significantly impact its hydrology and the characteristics of its exceptional flood pulse. The rapid economic development of the riparian countries has led to massive plans for hydropower construction, and projected climate change is expected to alter the monsoon patterns and increase temperature in the basin. The aim of this study is to assess the cumulative impact of these factors on the hydrology of the Mekong within next 20-30 yr. We downscaled the output of five general circulation models (GCMs) that were found to perform well in the Mekong region. For the simulation of reservoir operation, we used an optimisation approach to estimate the operation of multiple reservoirs, including both existing and planned hydropower reservoirs. For the hydrological assessment, we used a distributed hydrological model, VMod, with a grid resolution of 5 km × 5 km. In terms of climate change's impact on hydrology, we found a high variation in the discharge results depending on which of the GCMs is used as input. The simulated change in discharge at Kratie (Cambodia) between the baseline (1982-1992) and projected time period (2032-2042) ranges from -11% to +15% for the wet season and -10% to +13% for the dry season. Our analysis also shows that the changes in discharge due to planned reservoir operations are clearly larger than those simulated due to climate change: 25-160% higher dry season flows and 5-24% lower flood peaks in Kratie. The projected cumulative impacts follow rather closely the reservoir operation impacts, with an envelope around them induced by the different GCMs. Our results thus indicate that within the coming 20-30 yr, the operation of planned hydropower reservoirs is likely to have a larger impact on the Mekong hydrograph than the impacts of climate change, particularly during the dry season. On the other hand, climate change will increase the uncertainty of the

  18. 78 FR 6297 - Certain Frozen Fish Fillets From the Socialist Republic of Vietnam: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-30

    ... International Trade Administration Certain Frozen Fish Fillets From the Socialist Republic of Vietnam... frozen fish fillets from the Socialist Republic of Vietnam (``Vietnam''). The period of review (``POR... Republic of Vietnam'' from Christian Marsh, Deputy Assistant Secretary for Antidumping and...

  19. Investigations of the effect of guava as a possible tool in the control/management of Huanglongbing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The farmers of the Mekong Delta of Vietnam have discovered a unique interaction between citrus and guava, Psidium guajava L., that extends the commercial life of citrus plantings plagued by huanglongbing (HLB). Due to HLB, the normal life of citrus plantings in the region is 2-4 years. However, wh...

  20. Psychosocial readjustment of Canadian Vietnam veterans.

    PubMed

    Stretch, R H

    1991-02-01

    A survey study was conducted on the psychosocial readjustment of 164 of the estimated 10,000-40,000 Canadians who served in Vietnam with the U.S. military. Results indicate significantly greater rates of posttraumatic stress disorder (PTSD) compared with U.S. Vietnam veterans. Evidence of other psychosocial adjustment problems such as depression, inability to handle frustration and anger, difficulty in getting along with and trusting others, and family and marital problems, as well as poor physical health, was also found. Results suggest these problems are due, in part, to prolonged isolation from other Vietnam veterans, lack of recognition, and no readily available treatment for PTSD in Canada.

  1. Synergistic Utilization of Microwave Satellite Data and GRACE-Total Water Storage Anomaly for Improving Available Water Capacity Prediction in Lower Mekong Basin

    NASA Astrophysics Data System (ADS)

    Gupta, M.; Bolten, J. D.; Lakshmi, V.

    2015-12-01

    The Mekong River is the longest river in Southeast Asia and the world's eighth largest in discharge with draining an area of 795,000 km² from the eastern watershed of the Tibetan Plateau to the Mekong Delta including three provinces of China, Myanmar, Lao PDR, Thailand, Cambodia and Viet Nam. This makes the life of people highly vulnerable to availability of the water resources as soil moisture is one of the major fundamental variables in global hydrological cycles. The day-to-day variability in soil moisture on field to global scales is an important quantity for early warning systems for events like flooding and drought. In addition to the extreme situations the accurate soil moisture retrieval are important for agricultural irrigation scheduling and water resource management. The present study proposes a method to determine the effective soil hydraulic parameters directly from information available for the soil moisture state from the recently launched SMAP (L-band) microwave remote sensing observations. Since the optimized parameters are based on the near surface soil moisture information, further constraints are applied during the numerical simulation through the assimilation of GRACE Total Water Storage (TWS) within the physically based land surface model. This work addresses the improvement of available water capacity as the soil hydraulic parameters are optimized through the utilization of satellite-retrieved near surface soil moisture. The initial ranges of soil hydraulic parameters are taken in correspondence with the values available from the literature based on FAO. The optimization process is divided into two steps: the state variable are optimized and the optimal parameter values are then transferred for retrieving soil moisture and streamflow. A homogeneous soil system is considered as the soil moisture from sensors such as AMSR-E/SMAP can only be retrieved for the top few centimeters of soil. To evaluate the performance of the system in helping

  2. Fluvial sediment supply to a mega-delta reduced by shifting tropical-cyclone activity

    NASA Astrophysics Data System (ADS)

    Darby, Stephen E.; Hackney, Christopher R.; Leyland, Julian; Kummu, Matti; Lauri, Hannu; Parsons, Daniel R.; Best, James L.; Nicholas, Andrew P.; Aalto, Rolf

    2016-11-01

    The world’s rivers deliver 19 billion tonnes of sediment to the coastal zone annually, with a considerable fraction being sequestered in large deltas, home to over 500 million people. Most (more than 70 per cent) large deltas are under threat from a combination of rising sea levels, ground surface subsidence and anthropogenic sediment trapping, and a sustainable supply of fluvial sediment is therefore critical to prevent deltas being ‘drowned’ by rising relative sea levels. Here we combine suspended sediment load data from the Mekong River with hydrological model simulations to isolate the role of tropical cyclones in transmitting suspended sediment to one of the world’s great deltas. We demonstrate that spatial variations in the Mekong’s suspended sediment load are correlated (r = 0.765, P < 0.1) with observed variations in tropical-cyclone climatology, and that a substantial portion (32 per cent) of the suspended sediment load reaching the delta is delivered by runoff generated by rainfall associated with tropical cyclones. Furthermore, we estimate that the suspended load to the delta has declined by 52.6 ± 10.2 megatonnes over recent years (1981-2005), of which 33.0 ± 7.1 megatonnes is due to a shift in tropical-cyclone climatology. Consequently, tropical cyclones have a key role in controlling the magnitude of, and variability in, transmission of suspended sediment to the coast. It is likely that anthropogenic sediment trapping in upstream reservoirs is a dominant factor in explaining past, and anticipating future, declines in suspended sediment loads reaching the world’s major deltas. However, our study shows that changes in tropical-cyclone climatology affect trends in fluvial suspended sediment loads and thus are also key to fully assessing the risk posed to vulnerable coastal systems.

  3. Building an Extension Network in Vietnam.

    ERIC Educational Resources Information Center

    Poussard, H.

    1999-01-01

    Agricultural extension in Vietnam is in transition as the economy moves to a market orientation. The national extension service created in 1993 is constrained by lack of funding, staff, and access to current extension knowledge. (SK)

  4. Records of Wenchengia (Lamiaceae) from Vietnam

    PubMed Central

    Phillipson, Peter B; Suddee, Somran

    2016-01-01

    Abstract Background The monotypic genus Wenchengia (Lamiaceae) has been thought to be endemic to Hainan, China. This paper reports on historic records of Wenchengia alternifolia collected from Vietnam. The recent recuration and modernisation of the Paris herbarium greatly facilitated this discovery. New information During preparatory work supporting the account for the Lamiaceae of the Flora of Thailand, three specimens of Wenchengia from central Vietnam were found in the Herbarium of the Musuem National d'Histoire Naturelle in Paris (P), and subsequently two duplicates were found in the Herbarium at Kew (K, abbreviations following Thiers 2016). The specimens were collected in and before 1927 and it is not known if the species is still extant in Vietnam. Searches for extant populations should focus in the Ba Na Hills or Bach Ma National Park, central Vietnam. PMID:27660535

  5. Modelling the impact of large dams on flows and hydropower production of the Sekong, Sesan and Srepok Rivers in the Mekong Basin

    NASA Astrophysics Data System (ADS)

    Piman, T.; Cochrane, T. A.; Arias, M. E.

    2013-12-01

    Water flow patterns in the Mekong River and its tributaries are changing due to water resources development, particularly as a result of on-going rapid hydropower development of tributaries for economic growth. Local communities and international observers are concerned that alterations of natural flow patterns will have great impacts on biodiversity, ecosystem services, food securing and livelihood in the basin. There is also concern that un-coordinated dam development will have an adverse impact on energy production potential of individual hydropower plants. Of immediate concern is the proposed hydropower development in the transboundary Srepok, Sesan and Srekong (3S) Basin, which contributes up to 20% of the Mekong's annual flows, has a large potential for energy production, and provides critical ecosystem services to local people and the downstream Tonle Sap Lake and the Mekong delta. To assess the magnitude of potential changes in flows and hydropower production, daily flows were simulated over 20 years (1986-2005) using the SWAT and HEC ResSim models for a range of dam development and operations scenarios. Simulations of all current and proposed hydropower development in the 3S basin (41 dams) using an operation scheme to maximize electricity production will increase average dry seasonal flows by 88.1% while average wet seasonal flows decrease by 24.7% when compared to the baseline (no dams) scenario, About 55% of dry season flows changes are caused by the seven largest proposed dams (Lower Srepok 3, Lower Srepok4, Lower Sesan 3, Lower Sesan and Srepok 2, Xekong 5, Xekong 4, and Xe Xou). The total active storage of the existing and ongoing hydropower projects is only 6,616 million m3 while the cumulative active storage of the seven large proposed dams is 17,679 million m3. The Lower Srepok 3 project causes the highest impact on seasonal flow changes. Average energy production of the existing and ongoing hydropower projects is 73.2 GWh/day. Additional benefits

  6. Pen Branch delta expansion

    SciTech Connect

    Nelson, E.A.; Christensen, E.J.; Mackey, H.E.; Sharitz, R.R.; Jensen, J.R.; Hodgson, M.E.

    1984-02-01

    Since 1954, cooling water discharges from K Reactor ({anti X} = 370 cfs {at} 59 C) to Pen Branch have altered vegetation and deposited sediment in the Savannah River Swamp forming the Pen Branch delta. Currently, the delta covers over 300 acres and continues to expand at a rate of about 16 acres/yr. Examination of delta expansion can provide important information on environmental impacts to wetlands exposed to elevated temperature and flow conditions. To assess the current status and predict future expansion of the Pen Branch delta, historic aerial photographs were analyzed using both basic photo interpretation and computer techniques to provide the following information: (1) past and current expansion rates; (2) location and changes of impacted areas; (3) total acreage presently affected. Delta acreage changes were then compared to historic reactor discharge temperature and flow data to see if expansion rate variations could be related to reactor operations.

  7. Paragonimus and paragonimiasis in Vietnam: an update.

    PubMed

    Doanh, Pham Ngoc; Horii, Yoichiro; Nawa, Yukifumi

    2013-12-01

    Paragonimiasis is a food-borne parasitic zoonosis caused by infection with lung flukes of the genus Paragonimus. In Vietnam, research on Paragonimus and paragonimiasis has been conducted in northern and central regions of the country. Using a combination of morphological and molecular methods, 7 Paragonimus species, namely P. heterotremus, P. westermani, P. skrjabini, P. vietnamensis, P. proliferus, P. bangkokenis and P. harinasutai, have been identified in Vietnam. Of these, the first 3, P. heterotremus, P. westermani and P. skrjabini, are known to infect humans in other countries. However, in Vietnam, only P. heterotremus, found in some northern provinces, has been shown to infect humans. Even nowadays, local people in some northern provinces, such as Lai Chau and Yen Bai, are still suffering from P. heterotremus infection. In some provinces of central Vietnam, the prevalence and infection intensity of P. westermani metacercariae in freshwater crabs (the second intermediate hosts) are extremely high, but human cases have not been reported. Likewise, although P. skrjabini was found in Thanh Hoa Province, its pathogenicity to humans in Vietnam still remains uncertain. The results of molecular phylogenetic analyses of Vietnamese Paragonimus species provides new insights on the phylogeny and taxonomy of the genus Paragonimus. Comprehensive molecular epidemiological and geobiological studies on the genus in Vietnam and adjacent countries are needed to clarify the biodiversity and public health significance of the lung flukes.

  8. Changing fluxes of carbon and other solutes from the Mekong River

    PubMed Central

    Li, Siyue; Bush, Richard T.

    2015-01-01

    Rivers are an important aquatic conduit that connects terrestrial sources of dissolved inorganic carbon (DIC) and other elements with oceanic reservoirs. The Mekong River, one of the world’s largest rivers, is firstly examined to explore inter-annual fluxes of dissolved and particulate constituents during 1923–2011 and their associated natural or anthropogenic controls. Over this period, inter-annual fluxes of dissolved and particulate constituents decrease, while anthropogenic activities have doubled the relative abundance of SO42−, Cl− and Na+. The estimated fluxes of solutes from the Mekong decrease as follows (Mt/y): TDS (40.4) > HCO3− (23.4) > Ca2+ (6.4) > SO42− (3.8) > Cl− (1.74)~Na+ (1.7) ~ Si (1.67) > Mg2+ (1.2) > K+ (0.5). The runoff, land cover and lithological composition significantly contribute to dissolved and particulate yields globally. HCO3− and TDS yields are readily predicted by runoff and percent of carbonate, while TSS yield by runoff and population density. The Himalayan Rivers, including the Mekong, are a disproportionally high contributor to global riverine carbon and other solute budgets, and are of course underlined. The estimated global riverine HCO3− flux (Himalayan Rivers included) is 34014 × 109 mol/y (0.41 Pg C/y), 3915 Mt/y for solute load, including HCO3−, and 13553 Mt/y for TSS. Thereby this study illustrates the importance of riverine solute delivery in global carbon cycling. PMID:26522820

  9. Combination of multi-mission altimetry data along the Mekong River with spatio-temporal kriging

    NASA Astrophysics Data System (ADS)

    Boergens, Eva; Buhl, Sven; Dettmering, Denise; Klüppelberg, Claudia; Seitz, Florian

    2016-12-01

    River water-level time series at fixed geographical locations, so-called virtual stations, have been computed from single altimeter crossings for many years. Their temporal resolution is limited by the repeat cycle of the individual altimetry missions. The combination of all altimetry measurements along a river enables computing a water-level time series with improved temporal and spatial resolutions. This study uses the geostatistical method of spatio-temporal ordinary kriging to link multi-mission altimetry data along the Mekong River. The required covariance models reflecting the water flow are estimated based on empirical covariance values between altimetry observations at various locations. In this study, two covariance models are developed and tested in the case of the Mekong River: a stationary and a non-stationary covariance model. The proposed approach predicts water-level time series at different locations along the Mekong River with a temporal resolution of 5 days. Validation is performed against in situ data from four gauging stations, yielding RMS differences between 0.82 and 1.29 m and squared correlation coefficients between 0.89 and 0.94. Both models produce comparable results when used for combining data from Envisat, Jason-1, and SARAL for the time period between 2002 and 2015. The quality of the predicted time series turns out to be robust against a possibly decreasing availability of altimetry mission data. This demonstrates that our method is able to close the data gap between the end of the Envisat and the launch of the SARAL mission with interpolated time series.

  10. Changing fluxes of carbon and other solutes from the Mekong River.

    PubMed

    Li, Siyue; Bush, Richard T

    2015-11-02

    Rivers are an important aquatic conduit that connects terrestrial sources of dissolved inorganic carbon (DIC) and other elements with oceanic reservoirs. The Mekong River, one of the world's largest rivers, is firstly examined to explore inter-annual fluxes of dissolved and particulate constituents during 1923-2011 and their associated natural or anthropogenic controls. Over this period, inter-annual fluxes of dissolved and particulate constituents decrease, while anthropogenic activities have doubled the relative abundance of SO4(2-), Cl(-) and Na(+). The estimated fluxes of solutes from the Mekong decrease as follows (Mt/y): TDS (40.4) > HCO3(-) (23.4) > Ca(2+) (6.4) > SO4(2-) (3.8) > Cl(-) (1.74)~Na(+) (1.7) ~ Si (1.67) > Mg(2+) (1.2) > K(+ 0.5). The runoff, land cover and lithological composition significantly contribute to dissolved and particulate yields globally. HCO3(-) and TDS yields are readily predicted by runoff and percent of carbonate, while TSS yield by runoff and population density. The Himalayan Rivers, including the Mekong, are a disproportionally high contributor to global riverine carbon and other solute budgets, and are of course underlined. The estimated global riverine HCO3(-) flux (Himalayan Rivers included) is 34,014 × 10(9) mol/y (0.41 Pg C/y), 3915 Mt/y for solute load, including HCO3(-), and 13,553 Mt/y for TSS. Thereby this study illustrates the importance of riverine solute delivery in global carbon cycling.

  11. Characteristics of bedrock-alluvial anastomosed rivers: the Mekong River in Cambodia

    NASA Astrophysics Data System (ADS)

    Meshkova, Liubov. V.; Carling, Paul. A.

    2010-05-01

    The Mekong River is the 12th largest river in the world in terms of its length and mean annual discharge and yet it is poorly investigated. In the north eastern regions of Cambodia the Mekong River develops a multichannel pattern. It is characterised by a complex of intersecting bedrock channels, well vegetated alluvial and seasonally inundated islands, various types of sand bars, numerous bedrock exposures, rapids, waterfalls and deep bedrock pools which can be classified as a large mixed bedrock-alluvial anastomosed river of a tropical monsoonal climate zone. In order to complete a portrait of the river at the high level of details new data on morphology, geology and sediments were obtained during field surveys of a 120 km river section in Cambodia and combined with information from published literature and interpretation of available remote sensing images. This process has enabled to update and clarify knowledge on morphology of observed islands and floodplain, comprehensive geology and tectonic structures, hydrological regime and land cover. Complex analyses of the collected data have distinguished several geomorphological zones accordingly to frequency of morphological elements, the planview configuration of channels and vertical profile characteristics. The occurrence of each zone is a subject of variable controlling factors such as local topography, channel gradient, structural and tectonic elements and intercalating geological units. Evolution of the channel pattern has been considered at both short- and long term time scales. Historical cartographic and remote sensing materials were applied to determine planform channel changes over the last 50 years revealing the channels stability and cases of occasional, local erosion and deposition. The channel network was extracted from vector layers to examine channels and islands width and length parameters, bifurcation angles at the upstream end of islands and to obtain main channel network indices such as braiding

  12. Delta hepatitis in Malaysia.

    PubMed

    Sinniah, M; Dimitrakakis, M; Tan, D S

    1986-06-01

    Sera from one hundred and fifty nine Malaysian individuals were screened for the prevalence of delta markers. These included 15 HBsAg positive homosexuals, 16 acute hepatitis B cases, 9 chronic hepatitis B patients, 13 healthy HBsAg carriers and 106 intravenous (i.v.) drug abusers, of whom 27 were positive for HBsAg only and the rest were anti-HBc IgG positive but HBsAg negative. The prevalence of delta markers in the homosexuals was found to be 6.7%, in the HBsAg positive drug abusers 17.8%, in acute hepatitis B cases 12.5%. No evidence of delta infection was detected in healthy HBsAg carriers, chronic hepatitis B cases and HBsAg negative i.v. drug abusers. With reference to i.v. drug abusers, the prevalence of delta markers was higher in Malays (23%) than in Chinese (7%) although the latter had a higher HBsAg carrier rate. Although the HBsAg carrier rate in the homosexuals was high, their delta prevalence rate was low as compared to drug abusers. In Malaysia, as in other non-endemic regions, hepatitis delta virus transmission appeared to occur mainly via the parenteral and sexual routes. This is the first time in Malaysia that a reservoir of delta infection has been demonstrated in certain groups of the population at high risk for hepatitis B.

  13. Nile River Delta, Egypt

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The Nile River Delta of Egypt (30.0N, 31.0E) irrigated by the Nile River and its many distributaries, is some of the richest farm land in the world and home to some 45 million people, over half of Egypt's population. The capital city of Cairo is at the apex of the delta. Just across the river from Cairo can be seen the ancient three big pyramids and sphinx at Giza and the Suez Canal is just to the right of the delta.

  14. Delta Scuti stars: Theory

    NASA Technical Reports Server (NTRS)

    Guzik, J. A.

    1998-01-01

    The purpose of asteroseismology is not only to derive the internal structure of individual stars from their observed oscillation frequencies, but also to test and extend one's understanding of the physics of matter under the extremes of temperature, density, and pressure found in stellar interiors. In this review, the author hopes to point out what one can learn about the Sun by studying (delta) Scuti stars, as well as what one can learn about stars more massive or evolved than the Sun. He discusses some of the difficulties in theoretical approaches to asteroseismology for (delta) Scuti stars, using FG Vir, (delta) Scuti, and CD-24(degree) 7599 as examples.

  15. Basin-Wide Assessment on Impacts of Climate Change on Ecosystem Services in the Lower Mekong Basin

    EPA Science Inventory

    The Lower Mekong Basin (LMB) covers parts of riparian countries of Lao PDR, Viet Nam, Cambodia and Thailand and supports over 60 million people for food and livelihood. Recently, the LMB is threatened by climate change. This paper aims to quantify water yields and sediment retent...

  16. 45 CFR 506.10 - “Vietnam conflict” defined.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 3 2012-10-01 2012-10-01 false âVietnam conflictâ defined. 506.10 Section 506.10... OF THE WAR CLAIMS ACT OF 1948, AS AMENDED ELIGIBILITY REQUIREMENTS FOR COMPENSATION Prisoners of War § 506.10 “Vietnam conflict” defined. Vietnam conflict refers to the period beginning February 28,...

  17. 45 CFR 506.10 - “Vietnam conflict” defined.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false âVietnam conflictâ defined. 506.10 Section 506.10... OF THE WAR CLAIMS ACT OF 1948, AS AMENDED ELIGIBILITY REQUIREMENTS FOR COMPENSATION Prisoners of War § 506.10 “Vietnam conflict” defined. Vietnam conflict refers to the period beginning February 28,...

  18. 45 CFR 506.10 - “Vietnam conflict” defined.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 3 2011-10-01 2011-10-01 false âVietnam conflictâ defined. 506.10 Section 506.10... OF THE WAR CLAIMS ACT OF 1948, AS AMENDED ELIGIBILITY REQUIREMENTS FOR COMPENSATION Prisoners of War § 506.10 “Vietnam conflict” defined. Vietnam conflict refers to the period beginning February 28,...

  19. Drawing on Experience: A Study of Vietnam Veteran Artists

    ERIC Educational Resources Information Center

    Michel, Karl F.

    2004-01-01

    This study is an exploration of the art produced by American veterans of the Vietnam War. In the areas of artistic history, military service, and the creative process, Vietnam veteran artists are a diverse group, and there are many different ways of explaining the connection between Vietnam experience and their art. Some individuals made limited…

  20. 45 CFR 506.10 - “Vietnam conflict” defined.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 3 2013-10-01 2013-10-01 false âVietnam conflictâ defined. 506.10 Section 506.10... OF THE WAR CLAIMS ACT OF 1948, AS AMENDED ELIGIBILITY REQUIREMENTS FOR COMPENSATION Prisoners of War § 506.10 “Vietnam conflict” defined. Vietnam conflict refers to the period beginning February 28,...

  1. "Where Is Vietnam?" Antiwar Poetry and the Canon.

    ERIC Educational Resources Information Center

    Bibby, Michael

    1993-01-01

    Argues for the pervasive intervention of the Vietnam War in the cultural production of U.S. poetry. Questions the academic canon of post-World War II poetry and criticizes anthologies for ignoring Vietnam War poetry. Suggests why Vietnam War poetry has remained such an avoided subject. Lists anthologies including such poetry. (HB)

  2. 45 CFR 506.10 - “Vietnam conflict” defined.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 3 2014-10-01 2014-10-01 false âVietnam conflictâ defined. 506.10 Section 506.10... OF THE WAR CLAIMS ACT OF 1948, AS AMENDED ELIGIBILITY REQUIREMENTS FOR COMPENSATION Prisoners of War § 506.10 “Vietnam conflict” defined. Vietnam conflict refers to the period beginning February 28,...

  3. Voices from Vietnam: Veterans' Oral Histories in the Classroom.

    ERIC Educational Resources Information Center

    Hagopian, Patrick

    2000-01-01

    Discusses accounts given by Vietnam War veterans addressing issues such as the wannabe phenomenon, where not all people claiming to be veterans actually served in Vietnam, and the cultural script of the veteran. Highlights how oral histories are used by teachers and students. Describes a project where students interviewed Vietnam veterans. (CMK)

  4. Using the Arts to Teach Vietnam War Literature.

    ERIC Educational Resources Information Center

    Johannessen, Larry R.

    Starting a unit on Vietnam War literature by having students view slides of the Vietnam Veterans Memorial and listen to letters left there is just the first step in how an English teacher uses the arts to enhance student learning about the Vietnam War and its literature. After discussing their reactions to the slides and the offerings left at the…

  5. 78 FR 7452 - Steel Wire Garment Hangers From Vietnam; Determinations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-01

    ... COMMISSION Steel Wire Garment Hangers From Vietnam; Determinations On the basis of the record \\1\\ developed... imports of steel wire garment hangers from Vietnam, provided for in subheading 7326.20.00 of the... countervailing and antidumping duty orders on steel wire garment hangers from Vietnam. Background The...

  6. Developmental Book Activities and Needs in the Republic of Vietnam.

    ERIC Educational Resources Information Center

    Barnett, Stanley A.; And Others

    A three week survey was conducted to: (1) investigate the state of developmental book activity in Vietnam, (2) determine the priority of Vietnam's book needs, (3) develop program recommendations to meet the needs and (4) formulate regional recommendations. Although books published in Vietnam increased from 667 in 1961 to 1,566 in 1965, normal…

  7. Dams on Mekong tributaries as significant contributors of hydrological alterations to the Tonle Sap Floodplain in Cambodia

    NASA Astrophysics Data System (ADS)

    Arias, M. E.; Piman, T.; Lauri, H.; Cochrane, T. A.; Kummu, M.

    2014-02-01

    River tributaries have a key role in the biophysical functioning of the Mekong Basin. Of particular attention are the Sesan, Srepok, and Sekong (3S) rivers, which contribute nearly a quarter of the total Mekong discharge. Forty two dams are proposed in the 3S, and once completed they will exceed the active storage of China's large dam cascade in the upper Mekong. Given their proximity to the lower Mekong floodplains, the 3S dams could alter the flood-pulse hydrology driving the productivity of downstream ecosystems. Therefore, the main objective of this study was to quantify how hydropower development in the 3S would alter the hydrology of the Tonle Sap floodplain, the largest wetland in the Mekong and home to one of the most productive inland fisheries in the world. We coupled results from four numerical models representing the basin's surface hydrology, water resources development, and floodplain hydrodynamics. The scale of alterations caused by hydropower in the 3S was compared with the basin's definite future development scenario (DF) driven by the upper Mekong dam cascade. The DF or the 3S development scenarios could independently increase Tonle Sap's 30 day minimum water levels by 30 ± 5 cm and decrease annual water level fall rates by 0.30 ± 0.05 cm d-2. When analyzed together (DF + 3S), these scenarios are likely to eliminate all baseline conditions (1986-2000) of extreme low water levels, a particularly important component of Tonle Sap's environmental flows. Given the ongoing trends and large economic incentives in the hydropower business in the region, there is a high possibility that most of the 3S hydropower potential will actually be exploited and that dams would be built even in locations where there is a high risk of ecological disruptions. Hence, retrofitting current designs and operations to promote sustainable hydropower practices that optimize multiple river services - rather than just maximize hydropower generation - appear to be the most

  8. Dams on Mekong tributaries as significant contributors of hydrological alterations to the Tonle Sap Floodplain in Cambodia

    NASA Astrophysics Data System (ADS)

    Arias, M. E.; Piman, T.; Lauri, H.; Cochrane, T. A.; Kummu, M.

    2014-12-01

    River tributaries have a key role in the biophysical functioning of the Mekong Basin. Of particular interest are the Sesan, Srepok, and Sekong (3S) rivers, which contribute nearly a quarter of the total Mekong discharge. Forty two dams are proposed in the 3S, and once completed they will exceed the active storage of China's large dam cascade in the Upper Mekong. Given their proximity to the Lower Mekong floodplains, the 3S dams could alter the flood-pulse hydrology driving the productivity of downstream ecosystems. Therefore, the main objective of this study was to quantify how hydropower development in the 3S, together with definite future (DF) plans for infrastructure development through the basin, would alter the hydrology of the Tonle Sap's Floodplain, the largest wetland in the Mekong and home to one of the most productive inland fisheries in the world. We coupled results from four numerical models representing the basin's surface hydrology, water resources development, and floodplain hydrodynamics. The scale of alterations caused by hydropower in the 3S was compared with the basin's DF scenario driven by the Upper Mekong dam cascade. The DF or the 3S development scenarios could independently increase Tonle Sap's 30-day minimum water levels by 30 ± 5 cm and decrease annual water level fall rates by 0.30 ± 0.05 cm day-1. When analyzed together (DF + 3S), these scenarios are likely to eliminate all baseline conditions (1986-2000) of extreme low water levels, a particularly important component of Tonle Sap's environmental flows. Given the ongoing trends and large economic incentives in the hydropower business in the region, there is a high possibility that most of the 3S hydropower potential will be exploited and that dams will be built even in locations where there is a high risk of ecological disruption. Hence, retrofitting current designs and operations to promote sustainable hydropower practices that optimize multiple river services - rather than just

  9. Snow Cover and Precipitation Impacts on Dry Season Streamflow in the Lower Mekong Basin

    NASA Technical Reports Server (NTRS)

    Cook, Benjamin I.; Bell, A. R.; Anchukaitis, K. J.; Buckley, B. M.

    2012-01-01

    Climate change impacts on dry season streamflow in the Mekong River are relatively understudied, despite the fact that water availability during this time is critically important for agricultural and ecological systems. Analyses of two gauging stations (Vientiane and Kratie) in the Lower Mekong Basin (LMB) show significant positive correlations between dry season (March through May, MAM) discharge and upper basin snow cover and local precipitation. Using snow cover, precipitation, and upstream discharge as predictors, we develop skillful regression models for MAM streamflow at Vientiane and Kratie, and force these models with output from a suite of general circulation model (GCM) experiments for the twentieth and twenty-first centuries. The GCM simulations predict divergent trends in snow cover (decreasing) and precipitation (increasing) over the twenty-first century, driving overall negligible long-term trends in dry season streamflow. Our study demonstrates how future changes in dry season streamflow in the LMB will depend on changes in snow cover and precipitation, factors that will need to be considered when assessing the full basin response to other climatic and non-climatic drivers.

  10. 39Ar groundwater dating of a coastal aquifer in the Nam Dinh Province, Vietnam

    NASA Astrophysics Data System (ADS)

    Gerber, Christoph; Purtschert, Roland; Larsen, Flemming; Hoang, Hoan V.; Tran, Long V.; Tran, Luu T.; Pham, Nhan Q.; Sültenfuss, Jürgen

    2013-04-01

    In the south of Nam Dinh Province, Red River Delta, Vietnam, fresh Pleistocene groundwater has been identified to exist next to brackish pore waters in the Red River area (WAGNER et al. 2011). Extensive exploitation of the fresh water results in decreasing groundwater heads and migration of brackish water towards the freshwater (WAGNER et al., 2012). In order to understand the dynamics and origin of the fresh and saltwater and to predict the future evolution of the resource an extensive investigation using environmental tracers has been carried out. 39Ar, 85Kr, 3H/3He and stable noble gas measurements have been used for groundwater dating. Stable isotopes and other geochemical parameters (stable isotopes of the water molecule, water chemistry and gas composition) provide crucial information about the genesis of the water. Groundwater ages are modern in the recharge area and increase to > 1000 years towards the coast and northwards based on the 39Ar data (T1-2: 269 years). Depleted stable noble gas concentrations correlate with high concentrations of dissolved methane suggesting degassing due to the high methane partial pressure. Physical modelling of the degassing process (AESCHBACH-HERTIG et al., 2008) supported by concentrations of accumulated radiogenic 4He indicates that diffusion controlled the observed degassing at a late stage of the groundwater evolution path. References Aeschbach-Hertig, W., El-Gamal, H., Wieser, M., Palcsu, L., 2008. Modeling excess air and degassing in groundwater by equilibrium partitioning with a gas phase. Water Resour Res 44:W08449. Wagner, F., Trung, Ð. T., Phúc, H. Ð., Lindenmaier, F., 2011, Assessment of Groundwater Resources in Nam Dinh Province, Final Technical Report, Part A, Improvement of Groundwater Protection in Vietnam. Wagner, F., Ludwig, R. R., Noell, U., Hoang, H. V., Pham, N. Q., Larsen, F., Lindenmaier, F., 2012, Genesis of economic relevant fresh groundwater resources in Pleistocene/Neogene aquifers in Nam Dinh

  11. Federal Funding in the Delta.

    ERIC Educational Resources Information Center

    Reeder, Richard J.; Calhoun, Samuel D.

    2002-01-01

    The Lower Mississippi Delta region, especially the rural Delta, faces many economic challenges. The rural Delta has received much federal aid in basic income support and funding for human resource development, but less for community resource programs, which are important for economic development. Federal aid to the Delta is analyzed in terms of…

  12. The Lessons of the Vietnam War: Unit 13. Teacher's Manual: Strategies and Resources for Teaching the Vietnam War.

    ERIC Educational Resources Information Center

    Center for Social Studies Education, Pittsburgh, PA.

    This teacher's manual is designed to accompany the curriculum "The Lessons of the Vietnam War." For each of 12 units of the curriculum, this manual suggests projects for student research and classroom activities. The 12 units are entitled: (1) Introduction to Vietnam: land, history and culture; (2) America at war in Vietnam: decisions and…

  13. New records of marine algae in Vietnam

    NASA Astrophysics Data System (ADS)

    Le Hau, Nhu; Ly, Bui Minh; Van Huynh, Tran; Trung, Vo Thanh

    2015-06-01

    In May, 2013, a scientific expedition was organized by the Vietnam Academy of Science and Technology (VAST) and the Far Eastern Branch of the Russian Academy of Sciences (FEBRAS) through the frame of the VAST-FEBRAS International Collaboration Program. The expedition went along the coast of Vietnam from Quang Ninh to Kien Giang. The objective was to collect natural resources to investigate the biological and biochemical diversity of the territorial waters of Vietnam. Among the collected algae, six taxa are new records for the Vietnam algal flora. They are the red algae Titanophora pikeana (Dickie) Feldmann from Cu Lao Xanh Island, Laurencia natalensis Kylin from Tho Chu Island, Coelothrix irregularis (Harvey) Børgesen from Con Dao Island, the green algae Caulerpa oligophylla Montagne, Caulerpa andamanensis (W.R. Taylor) Draisma, Prudhomme et Sauvage from Phu Quy Island, and Caulerpa falcifolia Harvey & Bailey from Ly Son Island. The seaweed flora of Vietnam now counts 833 marine algal taxa, including 415 Rhodophyta, 147 Phaeophyceae, 183 Chlorophyta, and 88 Cyanobacteria.

  14. SWAT use of gridded observations for simulating runoff - a Vietnam river basin study

    NASA Astrophysics Data System (ADS)

    Vu, M. T.; Raghavan, S. V.; Liong, S. Y.

    2011-12-01

    Many research studies that focus on basin hydrology have used the SWAT model to simulate runoff. One common practice in calibrating the SWAT model is the application of station data rainfall to simulate runoff. But over regions lacking robust station data, there is a problem of applying the model to study the hydrological responses. For some countries and remote areas, the rainfall data availability might be a constraint due to many different reasons such as lacking of technology, war time and financial limitation that lead to difficulty in constructing the runoff data. To overcome such a limitation, this research study uses some of the available globally gridded high resolution precipitation datasets to simulate runoff. Five popular gridded observation precipitation datasets: (1) Asian Precipitation Highly Resolved Observational Data Integration Towards the Evaluation of Water Resources (APHRODITE), (2) Tropical Rainfall Measuring Mission (TRMM), (3) Precipitation Estimation from Remote Sensing Information using Artificial Neural Network (PERSIANN), (4) Global Precipitation Climatology Project (GPCP), (5) modified Global Historical Climatology Network version 2 (GHCN2) and one reanalysis dataset National Centers for Environment Prediction/National Center for Atmospheric Research (NCEP/NCAR) are used to simulate runoff over the Dakbla River (a small tributary of the Mekong River) in Vietnam. Wherever possible, available station data are also used for comparison. Bilinear interpolation of these gridded datasets is used to input the precipitation data at the closest grid points to the station locations. Sensitivity Analysis and Auto-calibration are performed for the SWAT model. The Nash-Sutcliffe Efficiency (NSE) and Coefficient of Determination (R2) indices are used to benchmark the model performance. This entails a good understanding of the response of the hydrological model to different datasets and a quantification of the uncertainties in these datasets. Such a

  15. The ecological complexity of the Thai-Laos Mekong River: III. Health status of Mekong catfish and cyprinids, evidence of bioaccumulative effects.

    PubMed

    Phanwichien, Kantimanee; Pradermwong, Apichart; Keenan, Helen E; Masawang, Kamonporn; Lauhachinda, Nitaya; Songsasen, Apisit; Sakultantimetha, Arthit; Bangkedphol, Sornnarin; Gaines, Alec F

    2010-11-01

    Histopathology of fish organs was used as biomarkers of toxicity from environmental pollutants. A total of 117 fishes comprising of 52 cyprinids and 65 catfishes were randomly collected from the Mekong River from 5 stations: Chiang Rai, Loei, Nongkhai, Nakhon Phanom and Ubonratchathani. The health of the fish collected in December and April, winter and summer respectively, was evaluated. All fish from the 5 stations developed pathologic lesions with the same characteristics in their livers, kidneys and spleen. In the liver, there was vacuolation of hepatocytes, accumulation of brownish-green granules in the cytoplasm of hepatocytes, necrosis of hepatocytes, granuloma formation and angiogenesis. Kidney lesions consisted of glomerular degeneration, necrosis and focal hyperplasia of renal tubules. In the spleen, there were haemorrhage, melanomacrophage centre infiltration and necrosis of the red pulp and white pulp. The pathologic severity of the catfish was found to be more severe than in the cyprinids and the catfish collected in summer were less healthy than the catfish collected in the winter. These histopathological appearances might arise from the fish feeding on the benthos and thereby accumulating toxic pollutants in their organs. The activities of the serum enzymes, Glutamic Oxalacetic Transaminase (GOT) and Glutamic Pyruvic Transaminase (GPT), were markedly increased, indicating detoxification activity. The highest activity of GOT found in the cyprinids from Chiang Rai 365.30 U/L whereas in the catfish from Nakhon Phanom the activity was 300.73 U/L. The highest GPT activity found in the cyprinids from Nakhon Phanom was 203.23 U/L where as in the catfish from the same station was GPT 389.77 U/L. According to the results from this study, catfish collected from Chiang Rai, Nakhon Phanom and Ubonratchathani showed more severe pathological changes than catfish from the other stations. Fish organs and river water were analysed for Polyaromatic Hydrocarbons (PAHs

  16. Strategy in the Vietnam War: Western Concepts, Eastern Conflict and the Roots of Failure.

    ERIC Educational Resources Information Center

    Weland, James

    1990-01-01

    Critiques U.S. military assumptions concerning the war in Vietnam. Discusses the North Vietnamese strategic approach to gaining control of South Vietnam. Traces the history of the Vietnam War, analyzing specific U.S. military operations in Vietnam and reasons for their failure. Contends that U.S. strategic ethnocentrism lead to defeat in Vietnam.…

  17. Coastal evolution between two giant rivers: The Chan May embayment in central Vietnam

    NASA Astrophysics Data System (ADS)

    Gouramanis, C.; Switzer, A.; Bristow, C.; Pham, D. T.; Mauz, B.; Pile, J.; Doan, L. D.; Hoang, Q. D.; Ngo, C. K.; Dao, N.; Polivka, P.; Soria, L.; Lee, Y.; Sloss, C.; Hoang, L. V.

    2015-12-01

    The coastal landscapes of Vietnam are dominated in the north and south by the very large Red and Mekong rivers. Central Vietnam, in contrast, has few large rivers that flow to the coastal zone. This coupled with the high relief (>1500 m) of the granitic Truong Son Range and shallow gradient continental shelf, has produced two different coastal geomorphologies. The first is a shallow basin infilled with a sequence of parallel, arcuate beach ridges, and the second includes the development of shore-parallel spits and coastal lagoons. All systems are Holocene in age and we present evidence of the Holocene evolution of the northward-facing, beach ridge strandplain located in the Chan May embayment, approximately 35 km north of Danang. This embayment is relatively small (5 km long at the beach and with a beach ridge sequence that spans 11 km from the modern beach to the base of the Truong Son Range) compared to other beach ridge strandplains to the north and south and serves as an analogue for the evolution of these larger systems. The Holocene evolution of the embayment was resolved using Ground Penetrating Radar (GPR), high-resolution sedimentological analysis and quartz Optically Stimulated Luminescence were used to investigate the internal stratigraphy and chronological development of the beach ridges at Chan May. The strandplain contains uniform, clean quartz-rich sediment interspersed by thin heavy mineral rich bands forming shallow-gradient beach ridges that have steadily prograded seaward during the regression after the mid-Holocene sea level highstand. As the beach ridges prograded seaward, a small river feeding directly from the Truong Son Range meandered across the strandplain and significantly modified the embayment. Recently, the river has become much reduced due to anthropogenic modification of the river and landscape. Prior to the Holocene marine highstand, the area was similarly characterized by a surface of prograding beach ridges that were eroded by

  18. Neogene sequence stratigraphy, Nam Con Son Basin, offshore Vietnam

    SciTech Connect

    McMillen, K.J.; Do Van Luu; Lee, E.K.; Hong, S.S.

    1996-12-31

    An integrated well log, biostratigraphic, and seismic stratigraphic study of Miocene to Recent deltaic sediments deposited in the Nam Con Son Basin offshore from southern Vietnam shows the influence of eustacy and tectonics on sequence development. Sediments consist of Oligocene non-marine rift-basin fill (Cau Formation), early to middle Miocene tide-dominated delta plain to delta front sediments (TB 1.5 to TB 2.5, Due and Thong Formations), and late Miocene to Recent marine shelf sediments (TB. 2.6 to TB 3.1 0, Mang Cau, Nam Con Son, and Bien Dong Formations). Eustacy controlled the timing of key surfaces and sand distribution in the tectonically-quiet early Miocene. Tectonic effects on middle to late Miocene sequence development consist of thick transgressive systems tracts due to basin-wide subsidence and transgression, sand distribution in the basin center, and carbonate sedimentation on isolated fault blocks within the basin. Third-order sequence boundaries (SB) are identified by spore peaks, sand stacking patterns, and channel incision. In the basin center, widespread shale beds with coal occur above sequence boundaries followed by transgressive sandstone units. These TST sandstones merge toward the basin margin where they lie on older HST sandstones. Maximum flooding surfaces (MFS) have abundant marine microfossils and mangrove pollen, a change in sand stacking pattern, and often a strong seismic reflection with downlap. Fourth-order genetic-type sequences are also interpreted. The MFS is the easiest marker to identify and correlate on well logs. Fourth-order SB occur within these genetic units but are harder to identify and correlate.

  19. Neogene sequence stratigraphy, Nam Con Son Basin, offshore Vietnam

    SciTech Connect

    McMillen, K.J. ); Do Van Luu; Lee, E.K.; Hong, S.S. )

    1996-01-01

    An integrated well log, biostratigraphic, and seismic stratigraphic study of Miocene to Recent deltaic sediments deposited in the Nam Con Son Basin offshore from southern Vietnam shows the influence of eustacy and tectonics on sequence development. Sediments consist of Oligocene non-marine rift-basin fill (Cau Formation), early to middle Miocene tide-dominated delta plain to delta front sediments (TB 1.5 to TB 2.5, Due and Thong Formations), and late Miocene to Recent marine shelf sediments (TB. 2.6 to TB 3.1 0, Mang Cau, Nam Con Son, and Bien Dong Formations). Eustacy controlled the timing of key surfaces and sand distribution in the tectonically-quiet early Miocene. Tectonic effects on middle to late Miocene sequence development consist of thick transgressive systems tracts due to basin-wide subsidence and transgression, sand distribution in the basin center, and carbonate sedimentation on isolated fault blocks within the basin. Third-order sequence boundaries (SB) are identified by spore peaks, sand stacking patterns, and channel incision. In the basin center, widespread shale beds with coal occur above sequence boundaries followed by transgressive sandstone units. These TST sandstones merge toward the basin margin where they lie on older HST sandstones. Maximum flooding surfaces (MFS) have abundant marine microfossils and mangrove pollen, a change in sand stacking pattern, and often a strong seismic reflection with downlap. Fourth-order genetic-type sequences are also interpreted. The MFS is the easiest marker to identify and correlate on well logs. Fourth-order SB occur within these genetic units but are harder to identify and correlate.

  20. American National Will and the Vietnam War

    DTIC Science & Technology

    1987-03-23

    changing American goals in the war was reinforced by General Bruce Palmer, the deputy Cormander of 2 U.S. Forces In Vietnem and 1 r the Vice Chief of Staff...1976, p. lo. 5. Cited in Summers, Op. cit., p. 11. 6. Palmer, Bruce . The 25-Year War: America’s Role in Vietnam. The University Press of Kentucky, 19...topic and fertile grounds for another article. Richard Nixon, in his most rec-nt book, No More Vietnams. 1985, and General Bruce Palmer, Jr. provide

  1. Flood Hazard Trends in the Mekong River during the 20th century due to monsoon variability

    NASA Astrophysics Data System (ADS)

    Delgado, Jose; Merz, Bruno; Apel, Heiko

    2013-04-01

    Flood trends were investigated in four stations of the lower Mekong River. Two types of changes were accounted for: trend in the mean and trend in the variance of the time series. A trend in the mean implies that the average flood events changed with time. A trend in variance implies that the frequency of low and high magnitude floods changed with time (Merz et al., 2012). Results showed that average flood events decreased during the 20th century. However, due to an increase in variance, the frequency of high magnitude floods increased towards the end of the 20th century (Delgado et al., 2010). This increase could not be detected by usual trend tests like Mann Kendall test or the ordinary least squares regression. The results agree with Katz and Brown (1992), who showed that variance changes are more important that changes in mean, when it comes to flood frequency trends. To investigate possible causes for the detected changes in flood variance, we looked at several large scale atmospheric circulation patterns cited in the literature. The Western Pacific monsoon index (Wang, 2001) showed the greatest resemblance with the flood data. A test of step change in variance was conducted which revealed a coinciding step change in variance between annual maximum discharge and the Western Pacific monsoon. A statistical model where monsoon variance forces flood frequency in the 20th century was tested. The results were statistically significant. This has the advantadge of by-passing the use of precipitation, which in this region is collected in a rather sparse network. Concerning climate change projections, a dynamic index like the Western Pacific monsoon index is better simulated by climate models than tropical precipitation (Wang, 2004, Douville et al. 2005). Another important result is the attribution of the detected changes. The Mekong River basin is located in a transition zone between the Indian and the Pacific oceans. Our results showed that the interannual variability

  2. Health Data Publications No. 5 (Revised). The Republic of Viet-Nam (South Viet-Nam).

    DTIC Science & Technology

    Animals of medical importance; Plants of medical importance; Water supply; Sanitation and waste disposal; Food and nutrition; Diseases of South Viet-Nam; Medical organization, administration, manpower; Veterinary facilities.

  3. Delta II Mars Pathfinder

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Final preparations for lift off of the DELTA II Mars Pathfinder Rocket are shown. Activities include loading the liquid oxygen, completing the construction of the Rover, and placing the Rover into the Lander. After the countdown, important visual events include the launch of the Delta Rocket, burnout and separation of the three Solid Rocket Boosters, and the main engine cutoff. The cutoff of the main engine marks the beginning of the second stage engine. After the completion of the second stage, the third stage engine ignites and then cuts off. Once the third stage engine cuts off spacecraft separation occurs.

  4. Forest Aboveground Biomass Estimation in the Greater Mekong, Subregion and Russian Siberia

    NASA Astrophysics Data System (ADS)

    Pang, Yong; Li, Zengyuan; Sun, Gouqing; Zhang, Zhiyu; Schmullius, Christiane; Meng, Shili; Ma, Zhenyu; Lu, Hao; Li, Shiming; Liu, Qingwang; Bai, Lina; Tian, Xin

    2016-08-01

    Forests play a vital role in sustainable development and provide a range of economic, social and environmental benefits, including essential ecosystem services such as climate change mitigation and adaptation. We summarized works in forest aboveground biomass estimation in Greater Mekong Subregion (GMS) and Russian Siberia (RuS). Both regions are rich in forest resources. These mapping and estimation works were based on multiple-source remote sensing data and some field measurements. Biomass maps were generated at 500 m and 30 m pixel size for RuS and GMS respectively. With the available of the 2015 PALSAR-2 mosaic at 25 m spacing, Sentinel-2 data at 20 m, we will work on the biomass mapping and dynamic study at higher spatial resolution.

  5. Impacts of Hydrological Alterations to the Tonle Sap Ecosystem of the Mekong River Basin

    NASA Astrophysics Data System (ADS)

    Arias, M. E.; Cochrane, T. A.

    2013-12-01

    The Tonle Sap is the largest and most important natural wetland in Southeast Asia. It covers an area of more than 15,000 km2 with a unique mosaic of natural and agricultural floodplain habitats that coexist with the largest fishery in the Mekong Basin. Accelerating hydropower development and climate change, however, are altering the Mekong's hydrology, which could negatively affect downstream ecosystems. The Tonle Sap is facing a two-fold problem. First, the link between its hydrology and ecosystem properties is not well understood. Second, potential ecological changes caused by future hydrological disruptions related to hydropower and climate change are unknown. Thus, the main objective of this study was to quantify how alterations to the Mekong hydrology could affect the Tonle Sap ecosystem. An assessment of landscape patterns revealed a distinct relationship between inundation and vegetation. Habitats in the Tonle Sap were divided into five groups based on annual flood duration, as well as physiognomic factors and human activity: (1) open water, (2) gallery forest, (3) seasonally flooded habitats, (4) transitional habitats, and (5) rainfed habitats. Large shifts could occur as a result of hydropower development scenarios by the 2030s; areas optimal for gallery forest could decrease by 82% from baseline conditions, whereas areas of rainfed habitats could increase by 10-13 % (813-1061 km2). An assessment of habitat patterns demonstrated that despite the complexity and intense human use of this ecosystem, the Mekong flood-pulse hydrology is the underlying driver of habitat characteristics by (1) determining inundation depth and duration, (2) creating the main soils gradient, (3) limiting the area cleared for agriculture, (4) influencing vegetation structure and water quality, and (5) shaping the composition of plant species. A numerical model was used to estimate aquatic net primary production (NPP) as a function of hydrology, sediments, and habitat characteristics

  6. Tetraodon palustris, a new freshwater pufferfish (Tetraodontiformes: Tetraodontidae) from the Mekong Basin of Thailand.

    PubMed

    Saenjundaeng, Pasakorn; Vidthayanon, Chavalit; Grudpun, Chaiwut

    2013-01-01

    Tetraodon palustris, new species, is described from the Mekong basin of Thailand. Tetraodon palustris differs from T cochinchinensis and T. fangi in having no ocellus on the flank and spinules dorsally from the interorbital region to the end of the dorsal-fin base. T. etraodon cochinchinensis is distinguished from T. fangi by having a longer snout (43.5-49.2% HL in T. cochinchinensis vs. 37.9-41.1% HL in T. fangi) and is covered with spinules dorsally from the front of the nasal organs to the end of the dorsal-fin base (vs. from the front of the eyes to the end of the dorsal-fin base in T. fangi).

  7. Infilling and flooding of the Mekong River incised valley during deglacial sea-level rise

    NASA Astrophysics Data System (ADS)

    Tjallingii, Rik; Stattegger, Karl; Wetzel, Andreas; Van Phach, Phung

    2010-06-01

    The abrupt transition from fluvial to marine deposition of incised-valley-fill sediments retrieved from the southeast Vietnamese shelf, accurately records the postglacial transgression after 14 ka before present (BP). Valley-filling sediments consist of fluvial mud, whereas sedimentation after the transgression is characterized by shallow-marine carbonate sands. This change in sediment composition is accurately marked in high-resolution X-ray fluorescence (XRF) core scanning records. Rapid aggradation of fluvial sediments at the river mouth nearly completely filled the Mekong incised valley prior to flooding. However, accumulation rates strongly reduced in the valley after the river-mouth system flooded and stepped back. This also affected the sediment supply to deeper parts of the southeast Vietnamese shelf. Comparison of the Mekong valley-filling with the East Asian sea-level history of sub- and inter-tidal sediment records shows that the transgressive surface preserved in the incised-valley-fill records is a robust sea-level indicator. The valley was nearly completely filled with fluvial sediments between 13.0 and 9.5 ka BP when sea-level rose rather constantly with approximately 10 mm/yr, as indicated by the East Asian sea-level record. At shallower parts of the shelf, significant sediment reworking and the establishment of estuarine conditions at the final stage of infilling complicates accurate dating of the transgressive surface. Nevertheless, incised-valley-fill records and land-based drill sites indicate a vast and rapid flooding of the shelf from the location of the modern Vietnamese coastline to the Cambodian lowlands between 9.5 ka and 8.5 ka BP. Fast flooding of this part of the shelf is related with the low shelf gradient and a strong acceleration of the East Asian sea-level rise from 34 to 9 meter below modern sea level (mbsl) corresponding to the sea-level jump of melt water pulse (MWP) 1C.

  8. River reach classification for the Greater Mekong Region at high spatial resolution

    NASA Astrophysics Data System (ADS)

    Ouellet Dallaire, C.; Lehner, B.

    2014-12-01

    River classifications have been used in river health and ecological assessments as coarse proxies to represent aquatic biodiversity when comprehensive biological and/or species data is unavailable. Currently there are no river classifications or biological data available in a consistent format for the extent of the Greater Mekong Region (GMR; including the Irrawaddy, the Salween, the Chao Praya, the Mekong and the Red River basins). The current project proposes a new river habitat classification for the region, facilitated by the HydroSHEDS (HYDROlogical SHuttle Elevation Derivatives at multiple Scales) database at 500m pixel resolution. The classification project is based on the Global River Classification framework relying on the creation of multiple sub-classifications based on different disciplines. The resulting classes from the sub-classification are later combined into final classes to create a holistic river reach classification. For the GMR, a final habitat classification was created based on three sub-classifications: a hydrological sub-classification based only on discharge indices (river size and flow variability); a physio-climatic sub-classification based on large scale indices of climate and elevation (biomes, ecoregions and elevation); and a geomorphological sub-classification based on local morphology (presence of floodplains, reach gradient and sand transport). Key variables and thresholds were identified in collaboration with local experts to ensure that regional knowledge was included. The final classification is composed 54 unique final classes based on 3 sub-classifications with less than 15 classes each. The resulting classifications are driven by abiotic variables and do not include biological data, but they represent a state-of-the art product based on best available data (mostly global data). The most common river habitat type is the "dry broadleaf, low gradient, very small river". These classifications could be applied in a wide range of

  9. Quaternary Morphodynamics for two large rivers: the Fly River, PNG, and the Mekong River, Cambodia.

    NASA Astrophysics Data System (ADS)

    Aalto, R. E.; Lauer, J. W.; Darby, S. E.; Goni, M. A.; Dietrich, W. E.

    2014-12-01

    During glacial marine transgressions, sediment & carbon are deposited due to the infilling of lowland fluvial systems, material that is then largely removed during ensuing regressions. Measuring & modelling these processes would help quantify the amount, timing, & preservation of these materials, providing insight into the morphodynamics of lowland fluvial systems in response to sea level change. We investigated the infilling dynamics of the Fly and Strickland Rivers, Papua New Guinea. Field data include: 14C dated deep cores recording base level evolution over the Holocene, sonar imaging of floodbasin stratigraphy, and the observations of blocked valley lakes and weathered erosional remnants from LGM conditions. Similar research was conducted on the Mekong River, Cambodia, where we have imaged basin fill stratigraphy and recorded the extent of blocked valley lakes. Such field data provide tantalizing empirical glimpses into the landscapes & flux buffering exhibited by large tropical rivers during glacial-interglacial transitions. We upscale our observations by modelling river system evolution, employing a GpU Lowland Landscape Evolution Model (GULLEM) to predict the evolution of the entire basin. A novel & powerful (>10 Tflops on an inexpensive computer) simulator, GULLEM models morphodynamics and estimates the accommodation space subsequently infilled during marine transgressions by representing a range of geomorphic processes, including: river & tributary incision, non-linear diffusion, sea level and isostatic change, hydraulic geometry, tectonic deformation, sediment production, transport & deposition, & tracking of the resulting stratigraphy. GULLEM's vectorized approach allows for massively parallel operation on GPUs (Graphics Processing Unit), making it practical to model coupled fluvial-landscape evolution for complex lowland river systems over large temporal and spatial scales. Our combined approach affords estimates for the timing and budgets of sediment

  10. Late Quaternary floodplain development along the Stung Sen River in the Lower Mekong Basin, Cambodia

    NASA Astrophysics Data System (ADS)

    Nagumo, Naoko; Sugai, Toshihiko; Kubo, Sumiko

    2013-09-01

    The Stung Sen River, the biggest tributary to Lake Tonle Sap in the Lower Mekong Basin in Cambodia, is characterized by large seasonal changes of water discharge under the Asian monsoon climate and seasonal changes in water level that reach at least 7 m and are controlled by the water level of the lake. The Stung Sen River floodplain consists of two geomorphic units: meander belt along the river channel and backmarsh. Coupled observations of outcrops along the river channel and arrays of sediment cores across the floodplain north of Kampong Chheuteal village and Kampong Thom City, c. 150 km and c. 70 km, respectively, reveal that floodplain environmental changes at c. 11 ka were possibly associated with the Holocene onset of the southeast Asian monsoon and probably with the emergence of Lake Tonle Sap. These observations also show that the present backmarsh-meander belt system was established about 5.5 ka along with the unique Mekong-Tonle Sap connection, characterized by a reversal in flow direction during the monsoon season. The meander belt materials are replaced as the river channel shifts on a decadal to centennial timescale. Backmarsh sediments at sites Kampong Chheuteal and Kampong Thom had a constant accumulation rate of about 0.5 mm/y during the Holocene, contrasting with rates of 0.1 mm/y during the late Pleistocene. At around 11 ka, a sand layer was deposited over all of the valley around Kampong Chheuteal, while wetlands enlarged around Kampong Thom, probably because of increased rainfall triggered by an enhancement of the Asian summer monsoon. This 11 ka horizon has since been covered by clayey sediments keeping pace with the accumulation of lacustrine sediments in Lake Tonle Sap.

  11. Improving Smallholder Farmer Biosecurity in the Mekong Region Through Change Management.

    PubMed

    Young, J R; Evans-Kocinski, S; Bush, R D; Windsor, P A

    2015-10-01

    Transboundary animal diseases including foot-and-mouth disease and haemorrhagic septicaemia remain a major constraint for improving smallholder large ruminant productivity in the Mekong region, producing negative impacts on rural livelihoods and compromising efforts to reduce poverty and food insecurity. The traditional husbandry practices of smallholders largely exclude preventive health measures, increasing risks of disease transmission. Although significant efforts have been made to understand the social aspects of change development in agricultural production, attention to improving the adoption of biosecurity has been limited. This study reviews smallholder biosecurity risk factors identified in the peer-reviewed literature and from field research observations conducted in Cambodia and Laos during 2006-2013, considering these in the context of a change management perspective aimed at improving adoption of biosecurity measures. Motivation for change, resistance to change, knowledge management, cultural dimensions, systems theory and leadership are discussed. Due to geographical, physical and resource variability, the implementation of biosecurity interventions suitable for smallholders is not a 'one size fits all'. Smallholders should be educated in biosecurity principles and empowered to make personal decisions rather than adopt prescribed pre-defined interventions. Biosecurity interventions should be aligned with smallholder farmer motivations, preferably offering clear short-term risk management benefits that elicit interest from smallholders. Linking biosecurity and disease control with improved livestock productivity provides opportunities for sustainable improvements in livelihoods. Participatory research and extension that improves farmer knowledge and practices offers a pathway to elicit sustainable broad-scale social change. However, examples of successes need to be communicated both at the 'evidence-based level' to influence regional policy

  12. Area Handbook Series: Vietnam: A Country Study

    DTIC Science & Technology

    1987-12-01

    Rhodes, Jesuit missionary, arrives in Hanoi. 1771 Tay Son Rebellion 1778 Most of Nguyen clan annihilated by the Tay Son. 1787 French missionary Pigneau de...The archive has 2.5 million pages of documentary material, 15 percent of which relates directly to Vietnam’s armed forces, internal security, law, and

  13. Vietnam, 1964-1973: An American Dilemma

    DTIC Science & Technology

    1990-10-01

    Vietnamese Ai Force. 1951-1975: An Analysis of its Role in Combat, and Fourteen Hours at Koh Tang. Washington: GPO, 2977. (Gov Doc D301.86:3/4.5...Bickford. Mobility, Support, Endurance: A Story of Naval QoRatina Logistics in the Vietnam Wart 1968. Washington: GPO. 1972. (Gov Doc D207.10/2:282

  14. Looking at the Vietnam War through Literature.

    ERIC Educational Resources Information Center

    Muller, Lisa S.

    1992-01-01

    Suggests a lesson plan in which history students discuss the effects of the Vietnam War on individuals and society. Explains that the students compare their responses before and after hearing a reading of two different works on the war. Includes suggested readings and questions for students to use in interviewing people in the community. (DK)

  15. Oral History and the Vietnam War.

    ERIC Educational Resources Information Center

    Brinker, William J.

    1997-01-01

    Reviews oral history works that examine various aspects of the Vietnam War. Incorporates diplomatic history and includes recollections of soldiers from a single county in Tennessee, veterans' families, and conscientious objectors. Covers the years of U.S. involvement, 1945-75. (MJP)

  16. College Course File: Representing the Vietnam War.

    ERIC Educational Resources Information Center

    James, David; Berg, Rick

    1989-01-01

    Outlines a course covering the history of film and televisual representations of the Vietnam War. Shows how to relate films to the social interests they serve, and describes how to relate form to function. Provides a list of recommended films, television shows, and readings for each of the course's 10 units. (MM)

  17. Which Vietnam Veterans Develop Posttraumatic Stress Disorders?

    ERIC Educational Resources Information Center

    Solkoff, Norman; And Others

    1986-01-01

    Vietnam combat veterans diagnosed as having Postraumatic Stress Disorder (PTSD) differed significantly in the intensity of their combat experiences and their perceptions of their homecoming experiences from controls who were also combat veterans. Neither early history nor immediate preservice factors differentiated the two groups. (Author/KS)

  18. The Vietnam War: History, Learning, and Leadership.

    ERIC Educational Resources Information Center

    Edwards, Tricia

    2002-01-01

    Focuses on the curriculum entitled "Echoes from the Wall: History, Learning and Leadership through the Lens of the Vietnam War Era." Discusses the purpose of the materials. States that the curriculum incorporates primary resources into the classroom while making history more immediate to students. (CMK)

  19. Teaching the Children of the Vietnam War.

    ERIC Educational Resources Information Center

    Filene, Peter

    1999-01-01

    Reminisces about how students reacted to learning about the Vietnam War within a U.S. history course where the students read the book "Dispatches" by Michael Herr which encouraged the students to empathize with their fathers who lived in that era. Discusses the implications this reaction has for teaching history. (CMK)

  20. Teaching the Vietnam War: A Conference Report.

    ERIC Educational Resources Information Center

    Winterstein, Stephen

    2000-01-01

    On May 6-7, 2000, the Foreign Policy Research Institute's (FPRI's) sixth History Institute convened with more than 40 high school and college history teachers to seek answers to the question: "How should we teach the history of the Vietnam War to our children today?" Not surprisingly, no simple answers were forthcoming. This conference…

  1. The Vietnam War and the Media.

    ERIC Educational Resources Information Center

    Elterman, Howard

    1988-01-01

    Surveys the author's contribution to the Center for Social Studies Education curriculum on the Vietnam War. Focuses on "How the War Was Reported," a unit which raises four questions concerning the responsibilities of the government and the press for keeping the public informed. Encourages use of the curriculum in teaching about the…

  2. Ecological Effects of the War in Vietnam

    ERIC Educational Resources Information Center

    Orians, Gordon H.; Pfeiffer, E. W.

    1970-01-01

    Research report on the severe ecological consequences of the defoliation program by American military forces in Vietnam. A significant fraction of mature trees in most forests are killed by single application of herbicides and almost completely killed by repeated sprayings. AAAS is urged to set up an international research program on the…

  3. Establishment of primary health care in Vietnam.

    PubMed

    Birt, C A

    1990-08-01

    Basic demographic and epidemiological data relevant to health problems in Vietnam are described in this paper. Existing health service arrangements are referred to, with particular emphasis on the strategy for development of primary health care. The establishment of the paediatric centre in Ho Chi Minh City is reported, and examples of its valuable work in primary health care development are described.

  4. Urbanization, migration, and Vietnam's spatial structure.

    PubMed

    Forbes, D

    1996-04-01

    In North Vietnam during the war years from the mid-1960s to the mid-1970s, cities were evacuated to minimize damage from bombing. As such, the urbanization process was checked. In the South, however, urban areas grew rapidly as people fled the fighting in the villages. Reunification of the country led to an outflow of residents from the largest southern cities back to the North or into new economic zones. From the mid-1970s to the early 1980s, Vietnam's total urban population remained static before beginning to increase slowly during the latter half of the 1980s. The rate of urbanization accelerated in the first half of the 1990s, although that process is not reflected in the available statistics. During 1979-89, the smaller cities grew faster than the larger ones, while most interprovincial migration occurred from North to South. Unemployment is a major problem in Vietnam's growing cities. The country's economic reforms require a more fluid labor market with fewer restrictions upon labor mobility. These needs are gradually undermining the strategy designed to contain urbanization, forcing planners to rethink urban development. The author discusses developing Vietnam's three main urban development corridors.

  5. Learning Vocabulary in Group Work in Vietnam

    ERIC Educational Resources Information Center

    Huong, Le Pham Hoai

    2006-01-01

    This study investigated learning vocabulary in group work at university in Vietnam. The students were studied in two kinds of group settings, "unassisted" and "assisted", the first consisting of five students from the same class level and the second of four from the same class and a student from a higher class. Differences were…

  6. Exploration and development offshore southern Vietnam

    SciTech Connect

    Ferguson, A.M. )

    1996-01-01

    In Vietnam, the major focus of the oil and gas industry is on the Nam Con Son and Cuu Long Basins in the southern offshore area. Major licensing first occurred here in the early 1970s. Some exploration was also undertaken by foreign companies in the early 1980s. In 1981, the Soviet Union undertook to assist Vietnam with the development of oil and gas. Vietsovpetro, a joint venture between the then Soviet Oil and Gas Ministry and the Vietnam Oil and Gas Corporation was formed. Most of Vietsovpetro's efforts have been to develop the Bach Ho field in the Cuu Long Basin. This now produces [approximately]130000 bopd. The most recent large scale licensing round occurred in 1992, and, at present, there are over thirty foreign companies active in these Basins' blocks . The first phase of exploration is ending and successes in the Nam Con Son Basin include the BP-led Lan Tay/Lan Do gas discoveries and Pedco's gas discoveries. Mitsubishi's and Petronas' oil discoveries in the Cuu Long Basin have attracted much attention also. The Dai Hung oil field (BHP-operated) has been producing since late 1994. Certain blocks are being appraised, and exploration work is also continuing. Areas of the Cuu Long Basin that were part of Vietsovpetro's acreage, but which may soon be re-licensed, have generated keen interest. The presence of an active upstream industry - exploring, appraising, developing and producing - indicates the emergence of Vietnam as an important East Asian oil and gas player.

  7. DELTA PHASE PLUTONIUM ALLOYS

    DOEpatents

    Cramer, E.M.; Ellinger, F.H.; Land. C.C.

    1960-03-22

    Delta-phase plutonium alloys were developed suitable for use as reactor fuels. The alloys consist of from 1 to 4 at.% zinc and the balance plutonium. The alloys have good neutronic, corrosion, and fabrication characteristics snd possess good dimensional characteristics throughout an operating temperature range from 300 to 490 deg C.

  8. Procedures for ensuring community involvement in multijurisdictional river basins: a comparison of the Murray-Darling and Mekong river basins.

    PubMed

    Chenoweth, Jonathan L; Ewing, Sarah A; Bird, Juliet F

    2002-04-01

    Community involvement is fundamental to the management of multijurisdictional river basins but, in practice, is very difficult to achieve. The Murray-Darling basin, in Australia, and the Mekong River basin in Southeast Asia are both cooperatively managed multijurisdictional river basins where the management authorities have expressed an aim of community involvement. In the Murray-Darling basin vigorous efforts have promoted a culture of community consultation throughout each of the state jurisdictions involved, although true participation has not necessarily been achieved. In the Mekong basin the community is much more diverse and the successes so far have been largely at the local level, involving action in subsections of the basin. These case studies suggest that community involvement in the form of community consultation across large multijurisdictional river basins is achievable, but more comprehensive participation is not necessarily possible.

  9. Decoding the drivers of bank erosion on the Mekong river: The roles of the Asian monsoon, tropical storms, and snowmelt

    PubMed Central

    Darby, Stephen E; Leyland, Julian; Kummu, Matti; Räsänen, Timo A; Lauri, Hannu

    2013-01-01

    We evaluate links between climate and simulated river bank erosion for one of the world's largest rivers, the Mekong. We employ a process-based model to reconstruct multidecadal time series of bank erosion at study sites within the Mekong's two main hydrological response zones, defining a new parameter, accumulated excess runoff (AER), pertinent to bank erosion. We employ a hydrological model to isolate how snowmelt, tropical storms and monsoon precipitation each contribute to AER and thus modeled bank erosion. Our results show that melt (23.9% at the upstream study site, declining to 11.1% downstream) and tropical cyclones (17.5% and 26.4% at the upstream and downstream sites, respectively) both force significant fractions of bank erosion on the Mekong. We also show (i) small, but significant, declines in AER and hence assumed bank erosion during the 20th century, and; (ii) that significant correlations exist between AER and the Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO). Of these modes of climate variability, we find that IOD events exert a greater control on simulated bank erosion than ENSO events; but the influences of both ENSO and IOD when averaged over several decades are found to be relatively weak. However, importantly, relationships between ENSO, IOD, and AER and hence inferred river bank erosion are not time invariant. Specifically, we show that there is an intense and prolonged epoch of strong coherence between ENSO and AER from the early 1980s to present, such that in recent decades derived Mekong River bank erosion has been more strongly affected by ENSO. PMID:23926362

  10. The geomorphological characteristics of the Mekong River in northern Cambodia: A mixed bedrock-alluvial multi-channel network

    NASA Astrophysics Data System (ADS)

    Meshkova, Liubov V.; Carling, Paul A.

    2012-04-01

    The controls on the development of channel morphology of bedrock-constrained rivers are poorly known. The relative importance of lithological and structural control on channel alignment and character in comparison with the role of hydraulic erosion of the substratum is unclear. In addition, bedrock rivers often have a variable sediment fill and can be described as mixed bedrock-alluvial systems. The Mekong River in northern Cambodia is an anastomosed mixed bedrock-alluvial channel, but little and poorly researched. In this paper information has been gathered from diverse literature sources; digital data sets showing topography, hydrology, geology and land cover; past aerial photographs; and maps. Such data, together with field survey, provide a clear picture of the Mekong River in this region. The channels may be classified into three types: primary, secondary, cross channels. The varying characteristics of these three help towards understanding the evolution of the modern Mekong. Similarly the two-fold classification of the islands reveals the relationship between island inundation characteristics and the annual monsoon flood cycle. The associated riparian vegetation ecotones include a rare and unusual seasonally-inundated forest. Spatial variations in lithology and structure, when combined with maps of river networks, reveals that the channel alignments locally reflect the geological factors that cause the regional topographical gradient. Fault-line constraints on the local slopes of the channel may induce backwater effects and consequent sedimentation patterns (alluvial overprints) or alternatively, steepening of the channels with concomitant reduction in sedimentation. These structural constraints, taken together, lead to the identification of a mixed bedrock-alluvial five-fold geomorphological zonation within the study area. The general absence of paleochannels, and terraces close to the modern river, indicates that the Mekong is laterally stable with a

  11. The Devil's in the Delta

    ERIC Educational Resources Information Center

    Luyben, William L.

    2007-01-01

    Students frequently confuse and incorrectly apply the several "deltas" that are used in chemical engineering. The deltas come in three different flavors: "out minus in", "big minus little" and "now versus then." The first applies to a change in a stream property as the stream flows through a process. For example, the "[delta]H" in an energy…

  12. High genetic diversity in cryptic populations of the migratory sutchi catfish Pangasianodon hypophthalmus in the Mekong River.

    PubMed

    So, N; Maes, G E; Volckaert, F A M

    2006-02-01

    The detection and conservation of spawning units is of crucial importance in highly migratory species. The sutchi catfish Pangasianodon hypophthalmus (Pangasiidae; Teleostei) is a common large-sized tropical fish, which migrates annually to several upstream spawning sites on the Lower Mekong River and feeds on the huge floodplain of the Lower Mekong and Tonle Sap for the other half of the year. We hypothesised that because of the relative size of the feeding and spawning habitat, genetic variability would be high and homogeneous in foraging populations, but that spawning stocks would be distinct in space and time. To test these predictions, 567 individuals from 10 geographic locations separated by up to 1230 km along the Lower Mekong River were genotyped at seven microsatellite loci. The level of genetic diversity was much higher than other freshwater fish and reached values comparable to marine species (mean H(e)=0.757). All samples collected at the potential spawning sites deviated from Hardy-Weinberg expectations, suggesting admixture. Individual-based clustering methods revealed genetic heterogeneity and enabled the detection of three genetically distinct sympatric populations. There was no evidence of recent reduction in effective population size in any population. Contrasting with the vast extent of the feeding grounds, the shortage of spawning grounds seems to have moved sutchi catfish towards diachronous spawning. Hence the sustainable exploitation of this natural resource hinges on the conservation of the limited spawning grounds and open migration routes between the spawning and feeding grounds.

  13. Monophyly of Opisthorchis viverrini populations in the lower Mekong Basin, using mitochondrial DNA nad1 gene as the marker.

    PubMed

    Thaenkham, Urusa; Nuamtanong, Supaporn; Sa-nguankiat, Surapol; Yoonuan, Tippayarat; Touch, Sarun; Manivong, Khemphavanh; Vonghachack, Youthanavanh; Sato, Megumi; Waikagul, Jitra

    2010-06-01

    The liver fluke, Opisthorchis viverrini, causes serious public-health problems in the Lower Mekong Basin. This study aimed to clarify whether O. viverrini populations may be genetically divided into sub-specific taxa. We collected 6 populations of O. viverrini from different places in Cambodia, Lao PDR, and Thailand, along both sides of the Mekong River, and analyzed the population structure of these using the mitochondrial nad1 gene as a marker. The results of the DNA polymorphism measurements, by theta-w (thetaw) and -pi (thetapi) values, neutrality tests, and mismatch distribution, suggested that the population of O. viverrini has expanded under the influence of purifying selection and selective sweep. The analysis of molecular variance (AMOVA) test revealed no significant genetic differences among the O. viverrini populations on opposite sides of the Mekong River. O. viverrini haplotypes occurred in multiple populations, and no distinct geographical clade. The star-like haplotype network confirmed a demographic expansion of the O. viverrini population. Overall, the genetic data from these populations suggested that the postulated existence of an O. viverrini species complex should be rejected. The bio-geographical diversity of O. viverrini populations should be explored further, using other appropriate markers and a wider range of samples from geographically different areas.

  14. Potential effects of dams on migratory fish in the Mekong River: lessons from salmon in the Fraser and Columbia Rivers.

    PubMed

    Ferguson, John W; Healey, Michael; Dugan, Patrick; Barlow, Chris

    2011-01-01

    We compared the effects of water resource development on migratory fish in two North American rivers using a descriptive approach based on four high-level indicators: (1) trends in abundance of Pacific salmon, (2) reliance on artificial production to maintain fisheries, (3) proportion of adult salmon that are wild- versus hatchery-origin, and (4) number of salmon populations needing federal protection to avoid extinction. The two rivers had similar biological and physical features but radically different levels of water resource development: the Fraser River has few dams and all are located in tributaries, whereas the Columbia River has more than 130 large mainstem and tributary dams. Not surprisingly, we found substantial effects of development on salmon in the Columbia River. We related the results to potential effects on migratory fish in the Mekong River where nearly 200 mainstem and tributary dams are installed, under construction, or planned and could have profound effects on its 135 migratory fish species. Impacts will vary with dam location due to differential fish production within the basin, with overall effects likely being greatest from 11 proposed mainstem dams. Minimizing impacts will require decades to design specialized fish passage facilities, dam operations, and artificial production, and is complicated by the Mekong's high diversity and productivity. Prompt action is needed by governments and fisheries managers to plan Mekong water resource development wisely to prevent impacts to the world's most productive inland fisheries, and food security and employment opportunities for millions of people in the region.

  15. Teaching the Vietnam War in the 1990s.

    ERIC Educational Resources Information Center

    Franklin, H. Bruce

    For an instructor who has been teaching the Vietnam War for over 30 years, the War has been teaching him for even longer. One of the objectives in teaching the Vietnam War in the 1990s is what it meant to teach the Vietnam War in the 1960s. It is easy to forget that the antiwar movement began as an attempt to educate the government and the nation,…

  16. Getting the Command and Control Right: A Vietnam Case Study

    DTIC Science & Technology

    2013-05-23

    GETTING THE COMMAND AND CONTROL RIGHT: A VIETNAM CASE STUDY A Monograph by MAJ Eddy J. Lee U.S. Army School of Advanced Military Studies...3. DATES COVERED (From - To) Jun 2012-May 2013 4. TITLE AND SUBTITLE Getting the Command and Control Right: A Vietnam Case Study 5a. CONTRACT...complicated problem of command and control in modern warfare. The challenges of command and control during the Vietnam War provide the basis for the

  17. Serum dioxin in Vietnam-era veterans - preliminary report

    SciTech Connect

    Not Available

    1987-08-14

    Agent orange, a defoliant used in Vietnam, was a mixture of 2,4-DD and 2,4,5-TS. During manufacture 2,4,5-T was contaminated with TCDD, a compound with marked toxicity in some species of experimental animals. In 1979, the US Congress responded to concerns of Vietnam veterans by passing Public Law 96-151 mandating epidemiologic studies of the possible health effects on Vietnam veterans of exposure to herbicides and their associated dioxin contaminants. In 1983, CDC developed a protocol for a historical cohort study of US Army veterans who had served in heavily sprayed areas of Vietnam. A report on that study is presented.

  18. 75 FR 54087 - Education Trade Mission to Indonesia and Vietnam

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-03

    ..., challenges and marketing strategies for each market. Commercial Setting Vietnam With a population of 86... affect both student recruitment strategies and the opportunities/challenges related to...

  19. Vietnam seeks help expanding voluntary surgical contraception.

    PubMed

    Piet-pelon, N J; Sukop, S

    1992-07-01

    Recent surveys by the Vietnamese Ministry of Health suggest that 60% of married women desire no more children. Yet only 2% of currently married women and less than 1/2 of 1% of their partners use sterilization. Underscoring the high unmet need for effective family planning, over 1 million abortions (legal in Vietnam for the past 20 years) are performed annually. This rate corresponds to 1 abortion for every live birth. The Ministry of Health has recently welcomed a variety of organizations, including AVSC, whose assistance can help expand the country's family planning programs. Sorely lacking in supplies, equipment, and trained personnel, Vietnam has merited priority status--2nd only to China and India--from the UNFPA, which has committed $36 million over the next 4 years. Other organizations currently working in Vietnam include the Population Council, the Population Crisis Committee, and the International Planned Parenthood Federation. Despite enormous casualties during the war years, and a decrease since the 1970s in average family size from 6 to 4 children, the population of Vietnam has continued to grow rapidly, far outpacing economic growth. Currently 67 million, the population is expected to reach 80 million by the year 2000. The average Vietnamese annual income is only $195, among the lowest in the world. Doi moi, the process of economic reform begun in 1986, coupled with new government incentives for families who have no more than 2 children, is changing the face of family planning in Vietnam. Newly opened pharmacies sell imported birth control pills and condoms (to those who can afford them), while government hospitals and health clinics provide mainly IUDs, in addition to limited supplies of pills and condoms. Throughout the country, some 8000 community-level health centers are staffed by nurse-midwives trained in family planning. Voluntary sterilization is available at the district, provincial, and national hospitals. All married women may obtain family

  20. Understanding pesticides in California's Delta

    USGS Publications Warehouse

    Kuivila, Kathryn; Orlando, James L.

    2012-01-01

    The Sacramento-San Joaquin River Delta (Delta) is the hub of California’s water system and also an important habitat for imperiled fish and wildlife. Aquatic organisms are exposed to mixtures of pesticides that flow through the maze of Delta water channels from sources including agricultural, landscape, and urban pest-control applications. While we do not know all of the effects pesticides have on the ecosystem, there is evidence that they cause some damage to organisms in the Delta. Decades of USGS research have provided a good understanding of when, where, and how pesticides enter the Delta. However, pesticide use is continually changing. New field studies and methods are needed so that scientists can analyze which pesticides are present in the Delta, and at what concentrations, enabling them to estimate exposure and ultimate effects on organisms. Continuing research will provide resource managers and stakeholders with crucial information to manage the Delta wisely.

  1. Martian deltas: Morphology and distribution

    NASA Technical Reports Server (NTRS)

    Rice, J. W., Jr.; Scott, D. H.

    1993-01-01

    Recent detailed mapping has revealed numerous examples of Martian deltas. The location and morphology of these deltas are described. Factors that contribute to delta morphology are river regime, coastal processes, structural stability, and climate. The largest delta systems on Mars are located near the mouths of Maja, Maumee, Vedra, Ma'adim, Kasei, and Brazos Valles. There are also several smaller-scale deltas emplaced near channel mouths situated in Ismenius Lacus, Memnonia, and Arabia. Delta morphology was used to reconstruct type, quantity, and sediment load size transported by the debouching channel systems. Methods initially developed for terrestrial systems were used to gain information on the relationships between Martian delta morphology, river regime, and coastal processes.

  2. Warfare rather than agriculture as a critical influence on fires in the late Holocene, inferred from northern Vietnam.

    PubMed

    Li, Zhen; Saito, Yoshiki; Dang, Phong X; Matsumoto, Eiji; Vu, Quang Lan

    2009-07-14

    Fire has played an essential role in the development of human civilization. Most previous research suggests that frequent-fire regimes in the late Holocene were associated with intensification of human activities, especially agriculture development. Here, we analyze fire regimes recorded in the Song Hong delta area of Vietnam over the past 5,000 years. In the prehistoric period, 2 long-term, low-charcoal abundance periods have been linked to periods of low humidity and cool climate, and 5 short-term fire regimes of 100-150 years in duration occurred at regular intervals of approximately 700 years. However, over the last 1,500 years, the number, frequency, and intensity of fire regimes clearly increased. Six intensified-fire regime periods in northern Vietnam during this time coincided with changes of Vietnamese dynasties and associated warfare and unrest. In contrast, agricultural development supported by rulers of stable societies at this time does not show a positive correlation with intensified-fire regime periods. Thus, warfare rather than agriculture appears to have been a critical factor contributing to fire regimes in northern Vietnam during the late Holocene.

  3. Hydrographic survey of Chaktomuk, the confluence of the Mekong, Tonlé Sap, and Bassac Rivers near Phnom Penh, Cambodia, 2012

    USGS Publications Warehouse

    Dietsch, Benjamin J.; Densmore, Brenda K.; Wilson, Richard C.

    2014-01-01

    Detailed hydrographic maps of Mekong, Tonlé Sap, and Bassac Rivers showing the riverbed elevations surveyed April 21–May 2, 2012, referenced to Ha Tien 1960 were produced. The surveyed area included a 2-km stretch of the Mekong River between the confluence with the Tonlé Sap and Bassac Rivers, and extended 4 km upstream and 3.6 km downstream from the 2,000-m confluence stretch of the Mekong River. In addition, 0.7 km of the Bassac River downstream and 3.5 km of the Tonlé Sap River (from the confluence to Chroy Changvar Bridge) upstream from their confluence with the Mekong River were surveyed. Riverbed features (such as dunes, shoals, and the effects of sediment mining, which were observed during data collection) are visible on the hydrographic maps. All surveys were completed at low annual water levels as referenced to nearby Mekong River Commission streamflow-gaging stations. Riverbed elevations surveyed ranged from 24.08 m below to 1.54 m above Ha Tien 1960.

  4. Trends and determinants of infant and under-five childhood mortality in Vietnam, 1986–2011

    PubMed Central

    Lee, Hwa-Young; Van Do, Dung; Choi, Sugy; Trinh, Oanh Thi Hoang; To, Kien Gia

    2016-01-01

    Background Although Vietnam has taken great efforts to reduce child mortality in recent years, a large number of children still die at early age. Only a few studies have been conducted to identify at-risk groups in order to provide baseline information for effective interventions. Objective The study estimated the overall trends in infant mortality rate (IMR) and under-five mortality rate (U5MR) during 1986–2011 and identified demographic and socioeconomic determinants of child mortality. Design Data from the Vietnam Multiple Indicator Cluster Surveys (MICSs) in 2000 (MICS2), 2006 (MICS3) and 2011 (MICS4) were analysed. The IMR and U5MR were calculated using the indirect method developed by William Brass. Unadjusted and adjusted odds ratios were estimated to assess the association between child death and demographic and socioeconomic variables. Region-stratified stepwise logistic regression was conducted to test the sensitivity of the results. Results The IMR and U5MR significantly decreased for both male and female children between 1986 and 2010. Male children had higher IMR and U5MR compared with females in all 3 years. Women who were living in the Northern Midlands and Mountain areas were more likely to experience child deaths compared with women who were living in the Red River Delta. Women who were from minor ethnic groups, had low education, living in urban areas, and had multiple children were more likely to have experienced child deaths. Conclusion Baby boys require more healthcare attention during the first year of their life. Comprehensive strategies are necessary for tackling child mortality problems in Vietnam. This study shows that child mortality is not just a problem of poverty but involves many other factors. Further studies are needed to investigate pathways underlying associations between demographic and socioeconomic conditions and childhood mortality. PMID:26950560

  5. Delta-doping of Semiconductors

    NASA Astrophysics Data System (ADS)

    Schubert, E. F.

    2005-08-01

    Part I: 1. Introduction E. F. Schubert; Part II: 2. Electronic structure of delta-doped semiconductors C. R. Proetto; Part III: 3. Recent progress in delta-like confinement of impurities in GaAs K. H. Ploog; 4. Flow-rate modulation epitaxy (FME) of III-V semiconductors T. Makimoto and Y. Horikoshi; 5. Gas source molecular beam epitaxy (MBE) of delta-doped III-V semiconductors D. Ritter; 6. Solid phase epitaxy for delta-doping in silicon I. Eisele; 7. Low temperature MBE of silicon H.-J. Gossmann; Part IV: 8. Secondary ion mass spectrometry of delta-doped semiconductors H. S. Luftmann; 9. Capacitance-voltage profiling E. F. Schubert; 10. Redistribution of impurities in III-V semiconductors E. F. Schubert; 11. Dopant diffusion and segregation in delta-doped silicon films H.-J. Gossmann; 12. Characterisation of silicon and delta-doped structures in GaAs R. C. Newman; 13. The DX-center in silicon delta-doped GaAs and AlxGa1-xAs P. M. Koenraad; Part V: 14. Luminescence and ellipsometry spectroscopy H. Yao and E. F. Schubert; 15. Photoluminescence and Raman spectroscopy of single delta-doped III-V semiconductor heterostructures J. Wagner and D. Richards; 16. Electron transport in delta-doped quantum wells W. T. Masselink; 17. Electron mobility in delta-doped layers P. M. Koenraad; 18. Hot electrons in delta-doped GaAs M. Asche; 19. Ordered delta-doping R. L. Headrick, L. C. Feldman and B. E. Weir; Part IV: 20. Delta-doped channel III-V field effect transistors (FETs) W.-P. Hong; 21. Selectively doped heterostructure devices E. F. Schubert; 22. Silicon atomic layer doping FET K. Nakagawa and K. Yamaguchi; 23. Planar doped barrier devices R. J. Malik; 24. Silicon interband and intersubband photodetectors I. Eisele; 25. Doping superlattice devices E. F. Schubert.

  6. Medical Hydrogeology of Asian Deltas: Status of Groundwater Toxicants and Nutrients, and Implications for Human Health

    PubMed Central

    Hoque, Mohammad A.; Butler, Adrian P.

    2015-01-01

    Drinking water, a fluid primarily for human hydration, is also a source of mineral nutrients. Groundwater, a drinking water source for more than 70% of inhabitants living in Asian deltas, has received much attention because of its naturally occurring arsenic, but the linkage of arsenic toxicity with other water constituents has not been studied. In addition, although nutrients are generally provided by food, in under developed rural settings, where people subsist on low nutrient diets, drinking-water-nutrients may supply quantities vital to human health thereby preventing diseases. Here, we show, using augmented datasets from three Asian deltas (Bengal, Mekong, and Red River), that the chemical content of groundwater is such that in some areas individuals obtain up to 50% or more of the recommended daily intake (RDI) of some nutrients (e.g., calcium, magnesium, iron) from just two litres of drinking water. We also show some indications of a spatial association of groundwater nutrients and health outcome using demographic health data from Bangladesh. We therefore suggest that an understanding of the association of non-communicable disease and poor nutrition cannot be developed, particularly in areas with high levels of dissolved solids in water sources, without considering the contribution of drinking water to nutrient and mineral supply. PMID:26712780

  7. Medical Hydrogeology of Asian Deltas: Status of Groundwater Toxicants and Nutrients, and Implications for Human Health.

    PubMed

    Hoque, Mohammad A; Butler, Adrian P

    2015-12-26

    Drinking water, a fluid primarily for human hydration, is also a source of mineral nutrients. Groundwater, a drinking water source for more than 70% of inhabitants living in Asian deltas, has received much attention because of its naturally occurring arsenic, but the linkage of arsenic toxicity with other water constituents has not been studied. In addition, although nutrients are generally provided by food, in under developed rural settings, where people subsist on low nutrient diets, drinking-water-nutrients may supply quantities critical to human health thereby preventing diseases. Here, we show, using augmented datasets from three Asian deltas (Bengal, Mekong, and Red River), that the chemical content of groundwater is so substantial that in some areas individuals obtain up to 50% or more of the recommended daily intake (RDI) of some nutrients (e.g., calcium, magnesium, iron) from just two litres of drinking water. We also show some indications of a spatial association of groundwater nutrients and health outcome using demographic health data from Bangladesh. We therefore suggest that an understanding of the association of non-communicable disease and poor nutrition cannot be developed, particularly in areas with high levels of dissolved solids in water sources, without considering the contribution of drinking water to nutrient and mineral supply.

  8. Sustainable hydropower in Lower Mekong Countries: Technical assessment and training travel report

    SciTech Connect

    Hadjerioua, Boualem; Witt, Adam M.

    2015-08-01

    The U.S. Agency for International Development (USAID), through their partnership with the U.S. Department of the Interior (DOI), requested the support of Oak Ridge National Laboratory (ORNL) to provide specialized technical assistance as part of the Smart Infrastructure for the Mekong (SIM) Program in Thailand. Introduced in July 2013 by U.S. Secretary of State John Kerry, SIM is a U.S. Government Inter-Agency program that provides Lower Mekong partner countries with targeted, demand-driven technical and scientific assistance to support environmentally sound, climate conscious and socially equitable infrastructure, clean energy development, and water resources optimization. The U.S. Government is committed to supporting sustainable economic development within the region by providing tools, best practices, technical assistance, and lessons learned for the benefit of partner countries. In response to a request from the Electricity Generating Authority of Thailand (EGAT), a SIM project was developed with two main activities: 1) to promote hydropower sustainability and efficiency through technical assessment training at two existing hydropower assets in Thailand, and 2) the design and implementation of one national and two or three regional science and policy workshops, to be co-hosted with EGAT, to build common understanding of and commitment to environmental and social safeguards for Mekong Basin hydropower projects. The U.S. Department of Energy (DOE) is leading the technical assessment (Activity 1), and has contracted ORNL to provide expert technical assistance focused on increasing efficiency at existing projects, with the goal of increasing renewable energy generation at little to no capital cost. ORNL is the leading national laboratory in hydropower analysis, with a nationally recognized and highly qualified team of scientists addressing small to large-scale systems (basin-, regional-, and national-scale) energy generation optimization analysis for DOE. The

  9. Vegetation fires and air pollution in Vietnam.

    PubMed

    Le, Thanh Ha; Thanh Nguyen, Thi Nhat; Lasko, Kristofer; Ilavajhala, Shriram; Vadrevu, Krishna Prasad; Justice, Chris

    2014-12-01

    Forest fires are a significant source of air pollution in Asia. In this study, we integrate satellite remote sensing data and ground-based measurements to infer fire-air pollution relationships in selected regions of Vietnam. We first characterized the active fires and burnt areas at a regional scale from MODIS satellite data. We then used satellite-derived active fire data to correlate the resulting atmospheric pollution. Further, we analyzed the relationship between satellite atmospheric variables and ground-based air pollutant parameters. Our results show peak fire activity during March in Vietnam, with hotspots in the Northwest and Central Highlands. Active fires were significantly correlated with UV Aerosol Index (UVAI), aerosol extinction absorption optical depth (AAOD), and Carbon Monoxide. The use of satellite aerosol optical thickness improved the prediction of Particulate Matter (PM) concentration significantly.

  10. Clinical microbiology during the Vietnam War.

    PubMed

    Washington, Michael; Brown, Matthew; Palys, Thomas; Tyner, Stuart; Bowden, Robert

    2009-11-01

    During the period of 1965-1968, over two dozen Army microbiologists were deployed to various locations in Southeast Asia in support of the Vietnam War. Their role was to serve both a clinical laboratory mission/function at the mobile Army surgical hospital and mobile laboratory level as well as to perform research roles in all of the facilities. They were essential to the formulation of medical intelligence as well as to the practice of operational medicine in the deployed environment. The results of their laboratory investigations provided commanders and military physicians with critical medical information for patient care, outbreak investigation, and forensic analysis. As with many soldiers in support of the infantry and armor combat forces, most of the work occurs behind the scenes and their contributions are often left out of the historical literature. This article presents a brief overview of microbiology performed by Army microbiologists during the Vietnam War.

  11. Limited effectiveness of household sand filters for removal of arsenic from well water in North Vietnam.

    PubMed

    Ilmiawati, Cimi; Thang, Nguyen Dinh; Iida, Machiko; Maeda, Masao; Ohnuma, Shoko; Yajima, Ichiro; Ohgami, Nobutaka; Oshino, Reina; Al Hossain, M M Aeorangajeb; Ninomiya, Hiromasa; Kato, Masashi

    2016-12-01

    Since well water utilized for domestic purposes in the Red River Delta of North Vietnam has been reported to be polluted by arsenic, barium, iron, and manganese, household sand filters consisting of various components are used. Information regarding the effectiveness of various sand filters for removal of the four toxic elements in well water is limited. In this study, arsenic levels in 13/20 of well water samples and 1/7 of tap water samples exceeded World Health Organization (WHO) health-based guideline value for drinking water. Moreover, 2/20, 6/20, and 4/20 of well water samples had levels exceeding the present and previous guideline levels for barium, iron, and manganese, respectively. Levels of iron and manganese, but not arsenic, in well water treated by sand filters were lower than those in untreated water, although previous studies showed that sand filters removed all of those elements from water. A low ratio of iron/arsenic in well water may not be sufficient for efficient removal of arsenic from household sand filters. The levels of barium in well water treated by sand filters, especially a filter composed of sand and charcoal, were significantly lower than those in untreated water. Thus, we demonstrated characteristics of sand filters in North Vietnam.

  12. Freshwater aquaculture nurseries and infection of fish with zoonotic trematodes, Vietnam.

    PubMed

    Phan, Van Thi; Ersbøll, Annette Kjær; Nguyen, Thanh Thi; Nguyen, Khue Viet; Nguyen, Ha Thi; Murrell, Darwin; Dalsgaard, Anders

    2010-12-01

    Residents of the Red River Delta region of northern Vietnam have a long tradition of eating raw fish. Fish-borne zoonotic trematodes (FZTs) are estimated to infect ≈1 million persons in Vietnam. It remains uncertain at what stages in the aquaculture production cycle fish become infected with FZTs. Newly hatched fish (fry) from 8 hatcheries and juveniles from 27 nurseries were therefore examined for FZT infection. No FZTs were found in fry from hatcheries. In nurseries, FZT prevalence in juveniles was 14.1%, 48.6%, and 57.8% after 1 week, 4 weeks, and when overwintered in ponds, respectively. FZT prevalence was higher in grass carp (p<0.001) than in other carp species. Results show that nurseries are hot spots for FZT infections in fish. Thus, sustainable FZT prevention strategies must address aquaculture management practices, particularly in nurseries, to minimize the risk of distributing infected juveniles to grow-out ponds and, subsequently, to markets for human consumption.

  13. Freshwater Aquaculture Nurseries and Infection of Fish with Zoonotic Trematodes, Vietnam

    PubMed Central

    Ersbøll, Annette Kjær; Nguyen, Thanh Thi; Nguyen, Khue Viet; Nguyen, Ha Thi; Murrell, Darwin; Dalsgaard, Anders

    2010-01-01

    Residents of the Red River Delta region of northern Vietnam have a long tradition of eating raw fish. Fish-borne zoonotic trematodes (FZTs) are estimated to infect ≈1 million persons in Vietnam. It remains uncertain at what stages in the aquaculture production cycle fish become infected with FZTs. Newly hatched fish (fry) from 8 hatcheries and juveniles from 27 nurseries were therefore examined for FZT infection. No FZTs were found in fry from hatcheries. In nurseries, FZT prevalence in juveniles was 14.1%, 48.6%, and 57.8% after 1 week, 4 weeks, and when overwintered in ponds, respectively. FZT prevalence was higher in grass carp (p<0.001) than in other carp species. Results show that nurseries are hot spots for FZT infections in fish. Thus, sustainable FZT prevention strategies must address aquaculture management practices, particularly in nurseries, to minimize the risk of distributing infected juveniles to grow-out ponds and, subsequently, to markets for human consumption. PMID:21122220

  14. LESSONS LEARNED, HEADQUARTERS, PROVISIONAL CORPS VIETNAM

    DTIC Science & Technology

    apparent. These provinces comprise the I Corps Tactical Zone ( I CTZ). The common borders with North Vietnam and Laos serve to shorten the enemy’s...General, III MAF, serves concurrently as Senior Advisor to the I CTZ Commander and as Senior US Military Commander in the northern corps. By mid-1967, US...disrupted throughout the Northern I CTZ (NICTZ) until the latter part of 1967. However, in December of that year a major enemy buildup began which

  15. Analysis of Vietnamization: Data Abstract. Volume 3

    DTIC Science & Technology

    1973-07-01

    AD/A-005 361 ANALYSIS OF VILTNAMIZATION: DATA ABS TRACT William G. Prince 0. 0 Bendix Corporation ca) V) Prepared for: Defense Advanced Research...DISSRISUTtOlN 8TATGEMENT Quali fied requestors may obcain copies of this report from D)C: It SURWLCMENTARV N6TES2 t TPONSORINGI %"LITANY ACTIVIY Defense Advanced ...BSR 4033 ANALYSIS OF VIETNAMIZATION: -"O DATA ABSTRACT Final Report Volume III Sponsored by: Defense Advanced Research Projects Agency ARPA Order No

  16. Analysis of Vietnamization: Summary and Evaluation

    DTIC Science & Technology

    1973-11-01

    x < 2.0 < x < 5.0 < x . 11.5 <x < 23.0 <A I’riendly KLA Kate , Friendly Inituated (x) An alternative assumptlon is that low enemy activity is really...Simmons, Edwin H., Brigadeer General, USMO (Ret.). "Marine Corps Operations in Vietnam, 1969-1972,ŕ Naval Review 1973, pp. 198-223. Soper , James B

  17. Exploration and development offshore southern Vietnam

    SciTech Connect

    Ferguson, A.M.

    1996-12-31

    In Vietnam, the major focus of the oil and gas industry is on the Nam Con Son and Cuu Long Basins in the southern offshore area. Major licensing first occurred here in the early 1970s. Some exploration was also undertaken by foreign companies in the early 1980s. In 1981, the Soviet Union undertook to assist Vietnam with the development of oil and gas. Vietsovpetro, a joint venture between the then Soviet Oil and Gas Ministry and the Vietnam Oil and Gas Corporation was formed. Most of Vietsovpetro`s efforts have been to develop the Bach Ho field in the Cuu Long Basin. This now produces {approximately}130000 bopd. The most recent large scale licensing round occurred in 1992, and, at present, there are over thirty foreign companies active in these Basins` blocks . The first phase of exploration is ending and successes in the Nam Con Son Basin include the BP-led Lan Tay/Lan Do gas discoveries and Pedco`s gas discoveries. Mitsubishi`s and Petronas` oil discoveries in the Cuu Long Basin have attracted much attention also. The Dai Hung oil field (BHP-operated) has been producing since late 1994. Certain blocks are being appraised, and exploration work is also continuing. Areas of the Cuu Long Basin that were part of Vietsovpetro`s acreage, but which may soon be re-licensed, have generated keen interest. The presence of an active upstream industry - exploring, appraising, developing and producing - indicates the emergence of Vietnam as an important East Asian oil and gas player.

  18. Tetanus in Southern Vietnam: Current Situation

    PubMed Central

    Thuy, Duong Bich; Campbell, James I.; Thanh, Tran Tan; Thuy, Cao Thu; Loan, Huynh Thi; Hao, Nguyen Van; Minh, Yen Lam; Tan, Le Van; Boni, Maciej F.; Thwaites, C. Louise

    2017-01-01

    In Vietnam, there are no accurate data on tetanus incidence to allow assessment of disease burden or vaccination program efficacy. We analyzed age structure of 786 tetanus cases admitted to a tertiary referral center in Vietnam for three separate years during an 18-year period to examine the impact of tetanus prevention programs, namely the Expanded Program on Immunization (EPI) and the Maternal and Neonatal Tetanus (MNT) initiative. Most cases were born before the initiation of EPI. Median age increased from 33 (interquartile range: 20–52) in 1994, to 46 (32–63) in 2012 (P < 0.001). Birth-year distribution was unchanged, indicating the same birth cohorts presented with tetanus in 1994, 2003, and 2012. Enzyme-linked immunosorbent assay measurements in 90 men and 90 women covered by MNT but not EPI showed 73.3% (95% confidence interval [CI]: 62.9–82.1%) of women had anti-tetanus antibody compared with 24.4% (95% CI: 15.9–34.7%) of men, indicating continued tetanus vulnerability in older men in Vietnam. PMID:27821690

  19. Mortality in Vietnam, 1979-1989.

    PubMed

    Merli, M G

    1998-08-01

    Little is known about past and present mortality in Vietnam, as the first official data on mortality have only recently become available from censuses taken in 1979 and 1989. Using these data, I estimate Vietnamese mortality during the intercensal period using two techniques that rely on age-specific growth rates from two successive age distributions. Intercensal emigration and differential completeness of census enumeration associated with massive outflows of refugees in the wake of the Vietnam War, population-redistribution policies, and a highly mobile population represent important sources of bias for the estimation of intercensal mortality. I incorporate several strategies to minimize bias from these sources and to select the method that is least sensitive to errors associated with them. Life expectancy at birth estimated for the 1979-1989 intercensal period is 61.4 years for males and 63.2 for females. These results suggest a trend of declining mortality between the 1970s and the 1980s and add solid empirical evidence to the debate over whether mortality in Vietnam has been deteriorating or improving.

  20. A renewal of astronomy education in Vietnam

    NASA Astrophysics Data System (ADS)

    Wentzel, Donat G.

    Vietnam was scientifically completely isolated for almost 30 years. With French help, several lecture courses have introduced modern astrophysics to Vietnamese physicists, and four students are studying abroad. The IAU program "Teaching for Astronomy Development" (TAD) has concentrated on modernizing the on-going astronomy course for students in the third year of the pedagogical universities. Three one-to-two week "Teachers' Workshops" have served to introduce selected up-to-date astronomical topics and a few modern teaching methods. The TAD program has also provided appropriate journals, books, a PC and educational software. A new text, Astrophysics, in Vietnamese and English on facing pages and with color pictures - apparently a first for any textbook in Vietnam - will first be used starting in September 2000. Future aditional activities: collaboration to plan a new astronomy course in the twelfth grade of the natural science branch of the secondary schools; collaboration so that the 41-cm telescope and astronomers in Hanoi can produce some simple quality science; helping the only planetarium in Vietnam to acquire a wider range of offerings; helping to create a set of B.Sc.-level astrophysics courses for three universities; and supporting the Vietnamese Astronomical Society in effective public outreach.

  1. Natural processes in delta restoration: application to the Mississippi Delta.

    PubMed

    Paola, Chris; Twilley, Robert R; Edmonds, Douglas A; Kim, Wonsuck; Mohrig, David; Parker, Gary; Viparelli, Enrica; Voller, Vaughan R

    2011-01-01

    Restoration of river deltas involves diverting sediment and water from major channels into adjoining drowned areas, where the sediment can build new land and provide a platform for regenerating wetland ecosystems. Except for local engineered structures at the points of diversion, restoration mainly relies on natural delta-building processes. Present understanding of such processes is sufficient to provide a basis for determining the feasibility of restoration projects through quantitative estimates of land-building rates and sustainable wetland area under different scenarios of sediment supply, subsidence, and sea-level rise. We are not yet to the point of being able to predict the evolution of a restored delta in detail. Predictions of delta evolution are based on field studies of active deltas, deltas in mine-tailings ponds, experimental deltas, and countless natural experiments contained in the stratigraphic record. These studies provide input for a variety of mechanistic delta models, ranging from radially averaged formulations to more detailed models that can resolve channels, topography, and ecosystem processes. Especially exciting areas for future research include understanding the mechanisms by which deltaic channel networks self-organize, grow, and distribute sediment and nutrients over the delta surface and coupling these to ecosystem processes, especially the interplay of topography, network geometry, and ecosystem dynamics.

  2. 77 FR 51514 - Steel Wire Garment Hangers From the Socialist Republic of Vietnam: Preliminary Affirmative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-24

    ... International Trade Administration Steel Wire Garment Hangers From the Socialist Republic of Vietnam... of steel wire garment hangers from the Socialist Republic of Vietnam (``Vietnam'').\\1\\ On August 2... Steel Wire Garment Hangers From the Socialist Republic of Vietnam: Preliminary Determination of Sales...

  3. The Future of Patriotism: The War Film, The Cinema Industry, and the Vietnam Veteran Movement.

    ERIC Educational Resources Information Center

    Camacho, Paul

    1990-01-01

    Examines the media's effect on attitudes about Vietnam veterans. Discusses the relationship between media and culture. Analyzes the film industry's ideological battle over Vietnam. Critiques the media's treatment of the Vietnam experience, and considers the impact of media portrayals of the war on the Vietnam Veteran's movement. (RW)

  4. Factor-Analytic Support for DSM-III's Post-Traumatic Stress Disorder for Vietnam Veterans.

    ERIC Educational Resources Information Center

    Silver, Steven M.; Iacono, C. U.

    1984-01-01

    Found substantial support for DSM-III's criteria for Post-Traumatic Stress using 405 Vietnam combat veterans and suggested that depression and anger be included as major signs. A comparison of symptom intensity between Vietnam veterans and non-Vietnam veterans showed Vietnam veterans experienced significantly greater intensities of DSM-III…

  5. 75 FR 55740 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Extension of Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-14

    ... International Trade Administration Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam... frozen warmwater shrimp from the Socialist Republic of Vietnam (``Vietnam''). The review covers the... of the antidumping duty orders on certain frozen warmwater shrimp from Vietnam and the...

  6. 77 FR 73424 - Certain Frozen Fish Fillets From the Socialist Republic of Vietnam: Partial Rescission of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-10

    ... International Trade Administration Certain Frozen Fish Fillets From the Socialist Republic of Vietnam: Partial... Socialist Republic of Vietnam (``Vietnam'').\\1\\ The Department is rescinding the review with respect to An... Fillets from the Socialist Republic of Vietnam, 68 FR 47909 (August 12, 2003). DATES: Effective...

  7. 76 FR 17837 - Certain Frozen Fish Fillets From the Socialist Republic of Vietnam: Initiation of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-31

    ... International Trade Administration Certain Frozen Fish Fillets From the Socialist Republic of Vietnam... Vietnam (``Vietnam''), received on February 28, 2011, meets the statutory and regulatory requirements for... the antidumping duty order on fish fillets from Vietnam was published in the Federal Register...

  8. 31 CFR 500.565 - Family remittances to nationals of Vietnam and Cambodia.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Vietnam and Cambodia. 500.565 Section 500.565 Money and Finance: Treasury Regulations Relating to Money... remittances to nationals of Vietnam and Cambodia. (a) The remittances specified in this section are authorized... relative is a national of Vietnam or Cambodia, is a resident of Vietnam, Cambodia, or a country to...

  9. 78 FR 40100 - Certain Frozen Fish Fillets from the Socialist Republic of Vietnam: Rescission of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-03

    ... International Trade Administration Certain Frozen Fish Fillets from the Socialist Republic of Vietnam... Republic of Vietnam (``Vietnam'') covering the period August 1, 2012, through January 31, 2013.\\1\\ On May... Socialist Republic of Vietnam: Initiation of Antidumping Duty New Shipper Review; 2012- 2013, 78 FR...

  10. 75 FR 27705 - Certain Frozen Warmwater Shrimp from the Socialist Republic of Vietnam: Extension of Final...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-18

    ... Frozen Warmwater Shrimp from the Socialist Republic of Vietnam: Extension of Final Results of Antidumping... Socialist Republic of Vietnam (``Vietnam''). This review covers the period February 1, 2008 through January... duty order on shrimp from Vietnam for Nhat Duc Co., Ltd. See Certain Frozen Warmwater Shrimp From...

  11. 38 CFR 3.313 - Claims based on service in Vietnam.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... in Vietnam. 3.313 Section 3.313 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS... Evaluations; Service Connection § 3.313 Claims based on service in Vietnam. (a) Service in Vietnam. Service in Vietnam includes service in the waters offshore, or service in other locations if the conditions...

  12. 76 FR 16384 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Extension of Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-23

    ... International Trade Administration Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam... warmwater shrimp (``shrimp'') from the Socialist Republic of Vietnam (``Vietnam''). The period of review for... notice of initiation of the new shipper review in the antidumping duty order on shrimp from Vietnam...

  13. 75 FR 20563 - Certain Frozen Warmwater Shrimp from the Socialist Republic of Vietnam: Extension of Final...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-20

    ... International Trade Administration Certain Frozen Warmwater Shrimp from the Socialist Republic of Vietnam... warmwater shrimp (``shrimp'') from the Socialist Republic of Vietnam (``Vietnam''). This review covers the... in the antidumping duty order on shrimp from Vietnam for Nhat Duc Co., Ltd. See Certain...

  14. Delta in Eberswalde

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This HiRISE image covers a portion of a delta that partially fills Eberswalde crater in Margaritifer Sinus. The delta was first recognized and mapped using MOC images that revealed various features whose presence required sustained flow and deposition into a lake that once occupied the crater. The HiRISE image resolves meter-scale features that record the migration of channels and delta distributaries as the delta grew over time. Differences in grain-size of sediments within the environments on the delta enable differential erosion of the deposits. As a result, coarser channel deposits are slightly more resistant and stand in relief relative to finer-grained over-bank and more easily eroded distal delta deposits. Close examination of the relict channel deposits confirms the presence of some meter-size blocks that were likely too coarse to have been transported by water flowing within the channels. These blocks may be formed of the sand and gravel that more likely moved along the channels that was lithified and eroded. Numerous meter-scale polygonal structures are common on many surfaces, but mostly those associated with more quiescent depositional environments removed from the channels. The polygons could be the result of deposition of fine-grained sediments that were either exposed and desiccated (dried out), rich in clays that shrunk when the water was removed, turned into rock and then fractured and eroded, or some combination of these processes.

    Image PSP_001336_1560 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on November 8, 2006. The complete image is centered at -23.8 degrees latitude, 326.4 degrees East longitude. The range to the target site was 256.3 km (160.2 miles). At this distance the image scale is 25.6 cm/pixel (with 1 x 1 binning) so objects 77 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel and north is up. The image was

  15. Pioneer Launch on Delta Vehicle

    NASA Technical Reports Server (NTRS)

    1969-01-01

    NASA launches the last in the series of interplanetary Pioneer spacecraft, Pioneer 10 from Cape Kennedy, Florida. The long-tank Delta launch vehicle placed the spacecraft in a solar orbit along the path of Earth's orbit. The spacecraft then passed inside and outside Earth's orbit, alternately speeding up and slowing down relative to Earth. The Delta launch vehicle family started development in 1959. The Delta was composed of parts from the Thor, an intermediate-range ballistic missile, as its first stage, and the Vanguard as its second. The first Delta was launched from Cape Canaveral on May 13, 1960 and was powerful enough to deliver a 100-pound spacecraft into geostationary transfer orbit. Delta has been used to launch civil, commercial, and military satellites into orbit. For more information about Delta, please see Chapter 3 in Roger Launius and Dennis Jenkins' book To Reach the High Frontier published by The University Press of Kentucky in 2002.

  16. Using First-Person Sources To Teach the Vietnam War.

    ERIC Educational Resources Information Center

    Dunn, Joe P.

    2003-01-01

    Discusses the use of first-person accounts in teaching history. Focuses on a course on Vietnam history called, "The Vietnam Experience." Explores different reading materials that are used in the course, as well as the author's own personal account. Includes a bibliography. (CMK)

  17. Vietnam: Education Financing. A World Bank Country Study.

    ERIC Educational Resources Information Center

    World Bank, Washington, DC.

    This study examines the system of education and training in Vietnam and poses the question: what changes in educational policies will ensure that students who pass through the system today will acquire the knowledge, skills, and attitudes needed for Vietnam to successfully complete the transition from a planned to a market economy? The report…

  18. Vietnam to Central America: A Case of Educational Failure.

    ERIC Educational Resources Information Center

    Kincheloe, Joe; Staley, George

    1983-01-01

    Vietnam and El Salvador can serve as models depicting the failure of American education to teach students to critically and objectively examine a current event. Only a decade after the Vietnam debacle, public schools are once again equating critical inquiry into the formulation of American foreign policy with anti-Americanism. (RM)

  19. Young-Adult Literature and the Vietnam War.

    ERIC Educational Resources Information Center

    Johannessen, Larry R.

    1993-01-01

    Describes how one teacher taught adolescent literature that deals with war and, specifically, the Vietnam War. Covers four key themes of Vietnam literature: combat narratives, the war at home, refugee experiences, and the next generation. Suggests ways of using these materials with students. (HB)

  20. Second Generation Effect of Vietnam: Adolescent Children of Combat Veterans.

    ERIC Educational Resources Information Center

    Dansby, Virginia Smejkal

    Although extensive research has focused upon the adjustment problems of the veterans of the Vietnam conflict, little data is available concerning their children. The purpose of this study was to provide a description of the adolescent children who have lived with Vietnam combat veteran fathers, comparing them (on the basis of social and personal…

  1. Latent Classes of PTSD Symptoms in Vietnam Veterans

    ERIC Educational Resources Information Center

    Steenkamp, Maria M.; Nickerson, Angela; Maguen, Shira; Dickstein, Benjamin D.; Nash, William P.; Litz, Brett T.

    2012-01-01

    The authors examined heterogeneity in posttraumatic stress disorder (PTSD) symptom presentation among veterans (n = 335) participating in the clinical interview subsample of the National Vietnam Veterans Readjustment Study. Latent class analysis was used to identify clinically homogeneous subgroups of Vietnam War combat veterans. Consistent with…

  2. Teaching the New Vietnam: It's a Country, Not a War

    ERIC Educational Resources Information Center

    McCornac, Dennis C.

    2008-01-01

    Vietnam has made remarkable progress over the past two decades in its transition to a market economy resulting in numerous changes to both its social and economic institutions. It is a nation at peace focusing on economic development and integrating into the world economy. Although the tragic events in Vietnam's history cannot be forgotten, the…

  3. Education and Economic, Political, and Social Change in Vietnam

    ERIC Educational Resources Information Center

    Huong, Pham Lan; Fry, Gerald W.

    2004-01-01

    This paper provides an overview of the complex relations among history, education, political economy, and social change in Vietnam. Vietnam has a long history of education and a literate culture. The evolution of Vietnamese culture and society is characterized by both persistence and change. Social and political persistence and change have been…

  4. LESSONS LEARNED, HEADQUARTERS, I FIELD FORCE VIETNAM ARTILLERY

    DTIC Science & Technology

    During the period 1 November 1967 through 31 January 1968, I Field Force Vietnam Artillery continued to support United States, Vietnamese, and Free...World Military Assistance Forces in II Corps Tactical Zone (CTZ). I Field Force Vietnam Artillery units, totaling two artillery groups, eleven

  5. A list of oribatid mites (Acari, Oribatida) of Vietnam

    PubMed Central

    Ermilov, Sergey G.

    2015-01-01

    Abstract A species list of identified oribatid mite taxa (Acari, Oribatida) in the fauna of Vietnam is provided. During 1967–2015, a total of 535 species/subspecies from 222 genera and 81 families was registered. Of these, 194 species/subspecies were described as new for science from Vietnam. PMID:26798306

  6. U.S.-Vietnam Relations: Background and Issues for Congress

    DTIC Science & Technology

    2006-03-02

    4,039.2 2005 6,522.3 1,151.3 7,673.6 -5,371.0 Major Imports from Vietnam clothing, footwear, wooden furniture, frozen shrimp, petroleum products, cashew ... nuts , coffee Major Exports to Vietnam aircraft, mining equipment, electronic machinery, steel wire, raw cotton, plastics Source: U.S. International

  7. Refighting the Last War: Afghanistan and the Vietnam Template

    DTIC Science & Technology

    2009-12-01

    exact political and military reenactment of the Vietnam War, and the lack of self-awareness of the repetition of events 50 years ago is deeply...as in the Bill Murray film ) epitomized by the paradigmatic tragedy of Hamburger Hill in Vietnam. Instead of “clear, hold and build,” what the U.S

  8. Effective Primary Schools in Geographically Isolated Areas of Vietnam

    ERIC Educational Resources Information Center

    Ikeda, Miyako

    2010-01-01

    This study identifies the major characteristics of "effective" primary schools in isolated areas in Vietnam. It suggests areas in which the implementation of beneficial changes can occur. Pupils in isolated areas of Vietnam are, in many respects, educationally disadvantaged. Usually, these pupils are in schools that have fewer…

  9. Transforming Vietnam's Medical Education through E-Learning

    ERIC Educational Resources Information Center

    Churton, Michael W.

    2011-01-01

    The costs for providing medical school education and services in Vietnam's universities continue to increase. Through a collaborative project between the Government of the Netherlands and Vietnam's Ministry of Health, a five year experimental program to develop in-country capacity and reduce the dependence upon a foreign medical service delivery…

  10. Reaction of Vietnam Veterans to the Persian Gulf War.

    ERIC Educational Resources Information Center

    Kobrick, Felice R.

    1993-01-01

    Reviews evolution of the concept of combat-related posttraumatic stress disorder and analyzes reports of Vietnam veterans' reactions to the Persian Gulf War. Presents case study of Vietnam veteran whose traumatic memories were reawakened with the onset of the Persian Gulf War, and discusses implications for social work practice. (Author/NB)

  11. Primary English Language Education Policy in Vietnam: Insights from Implementation

    ERIC Educational Resources Information Center

    Nguyen, Hoa Thi Mai

    2011-01-01

    The introduction of English in primary education curricula is a phenomenon occurring in many non-English-speaking countries in Asia, including Vietnam. Recently, the Ministry of Education and Training (MOET) in Vietnam issued guidelines for the piloting of an English as a foreign language (EFL) primary curriculum in which English is taught as a…

  12. Teaching English in Primary Schools in Vietnam: An Overview

    ERIC Educational Resources Information Center

    Hoa, Nguyen Thi Mai; Tuan, Nguyen Quoc

    2007-01-01

    This paper examines the English language situation at primary school level in Vietnam from a language planning perspective. It examines language policy for foreign language teaching in Vietnam to provide a picture of the role of English in foreign language education. It analyses language-in-education policy, curriculum and teaching materials, and…

  13. The History and Future of Community Colleges in Vietnam

    ERIC Educational Resources Information Center

    Le, Anh T.

    2013-01-01

    Since 1986, with the creation of the Renovation ("Doi moi") policy, Vietnam has demonstrated a strong commitment to the improvement of its higher education system. After 25 years of opening its doors to the global educational environment, Vietnam has achieved some notable accomplishments. The country's higher educational system has…

  14. Meiobenthos assemblages in the mekong estuarine system with special focus on free-living marine nematodes

    NASA Astrophysics Data System (ADS)

    Quang, Ngo Xuan; Vanreusel, Ann; Smol, Nic; Chau, Nguyen Ngoc

    2010-12-01

    Meiobenthos assemblages in eight estuaries of the Mekong river system were investigated in August 2008 (from the Cua Tieu estuary to the Tran De estuary). In each estuary, one sampling station was established for meiobenthos sampling. Twelve major taxa of meiobenthos were recorded in this estuarine system, including Nematoda, Copepoda, Turbellaria, Polychaeta, Oligochaeta, Tardigrada, Bivalvia, Ostracoda, Amphipoda, Cumacea, Gastrotricha, Gastropoda, and Crustacean Nauplii larvae. The densities of the meiobenthos range from 581 to 3168 inds/10 cm2. Nematodes always occupy the highest numbers with a percentage ranging from 64-99%. There are 135 nematode genera recorded in this study with the following as dominant genera Desmodora, Leptolaimus, Halalaimus, Thalassomonhystera, Theristus, Daptonema, Rhynchonema, Parodontophora, and Oncholaimus. Although the biodiversity of the meiobenthos at higher taxa level is not high compared to other marine environments, the estimates of nematode biodiversity at the genus level indicates high values. The increase in number of genera with increasing sampling intensity illustrate that the diversity is underestimated and would have been higher if the authors had considered a larger number of individuals, more replicates per station, and more sampling stations.

  15. Estimation of Vietnam national burden of disease 2008.

    PubMed

    Nhung, Nguyen Thi Trang; Long, Tran Khanh; Linh, Bui Ngoc; Vos, Theo; Huong, Nguyen Thanh; Anh, Ngo Duc

    2014-09-01

    Burden of disease has been used to assess population health status. This article presents the first estimations of burden of disease in Vietnam in 2008 using disability-adjusted life years (DALYs). DALYs were calculated using the Global Burden of Disease (GBD) methods. Incidence, prevalence of diseases, and causes of death was extracted from Vietnam data. Disability weights were borrowed from GBD and Dutch research. In 2008, the total burden of disease in Vietnam was 12.3 million DALYs. Noncommunicable diseases dominated the total burden of diseases in Vietnam, accounting for 71% of the total burden, and cardiovascular disease was the leading cause group of premature death. While pneumonia was an important cause of burden in Vietnamese children, stroke and depression were the main causes of disease burden among adults. The study provides a snapshot of Vietnamese health status and offers guidance for health policymaking in Vietnam.

  16. Vietnam: Echoes from the Wall. History, Learning and Leadership through the Lens of the Vietnam War Era. Teachers' Guide.

    ERIC Educational Resources Information Center

    Pearson, Patricia; Percoco, James; Sossaman, Stephen; Wilson, Rob

    Today, the Vietnam Veterans Memorial (The Wall) has moved beyond its role as an international symbol of healing and stands as a living history lesson, but many of today's young people have a limited knowledge of the Vietnam War. This guide consists of an interactive curriculum enabling teachers to delve into the lessons of that chaotic period and…

  17. Authoritative Voices and the Vietnam Experience: Teaching about Vietnam during the Gulf War.

    ERIC Educational Resources Information Center

    Sears, Laurie J.

    1991-01-01

    Experiences of a college teacher teaching a course on the Vietnam War during the Persian Gulf Crisis illustrate the impact that teaching history can have on the consciousness of students. Respect for other cultures and other races are essential before students can stop glorifying war. (SLD)

  18. [Delta-9-tetrahydrocannabinol pharmacokinetics].

    PubMed

    Goullé, J-P; Saussereau, E; Lacroix, C

    2008-08-01

    Delta-9-tetrahydrocannabinol (Delta-9-THC) is the main psychoactive ingredient of cannabis. Smoking is currently most common use of cannabis. The present review focuses on the pharmacokinetics of THC. The variability of THC in plant material which has significantly increased in recent years leads to variability in tissue THC levels from smoking, which is, in itself, a highly individual process. This variability of THC content has an important impact on drug pharmacokinetics and pharmacology. After smoking THC bioavailability averages 30%. With a 3.55% THC cigarette, a peak plasma level near 160 ng/mL occurs approximately 10 min after inhalation. THC is eliminated quickly from plasma in a multiphasic manner and is widely distributed to tissues, which is responsible for its pharmacologic effects. Body fat then serves as a long-term storage site. This particular pharmacokinetics explains the noncorrelation between THC blood level and clinical effects as is observed for ethanol. A major active 11-hydroxy metabolite is formed after both inhalation and oral dosing (20 and 100% of parent, respectively). The elimination of THC and its many metabolites, mainly THC-COOH, occurs via the feces and urine for several weeks. Thus, to confirm abstinence, urine THC-COOH analysis would be a useful tool. A positive result could be checked by gas chromatography-mass spectrometry THC blood analysis, indicative of a recent cannabis exposure.

  19. Modelling Hydrologic Processes in the Mekong River Basin Using a Distributed Model Driven by Satellite Precipitation and Rain Gauge Observations.

    PubMed

    Wang, Wei; Lu, Hui; Yang, Dawen; Sothea, Khem; Jiao, Yang; Gao, Bin; Peng, Xueting; Pang, Zhiguo

    2016-01-01

    The Mekong River is the most important river in Southeast Asia. It has increasingly suffered from water-related problems due to economic development, population growth and climate change in the surrounding areas. In this study, we built a distributed Geomorphology-Based Hydrological Model (GBHM) of the Mekong River using remote sensing data and other publicly available data. Two numerical experiments were conducted using different rainfall data sets as model inputs. The data sets included rain gauge data from the Mekong River Commission (MRC) and remote sensing rainfall data from the Tropic Rainfall Measurement Mission (TRMM 3B42V7). Model calibration and validation were conducted for the two rainfall data sets. Compared to the observed discharge, both the gauge simulation and TRMM simulation performed well during the calibration period (1998-2001). However, the performance of the gauge simulation was worse than that of the TRMM simulation during the validation period (2002-2012). The TRMM simulation is more stable and reliable at different scales. Moreover, the calibration period was changed to 2, 4, and 8 years to test the impact of the calibration period length on the two simulations. The results suggest that longer calibration periods improved the GBHM performance during validation periods. In addition, the TRMM simulation is more stable and less sensitive to the calibration period length than is the gauge simulation. Further analysis reveals that the uneven distribution of rain gauges makes the input rainfall data less representative and more heterogeneous, worsening the simulation performance. Our results indicate that remotely sensed rainfall data may be more suitable for driving distributed hydrologic models, especially in basins with poor data quality or limited gauge availability.

  20. Observations on Neotricula aperta (Gastropoda: Pomatiopsidae) population densities in Thailand and central Laos: implications for the spread of Mekong schistosomiasis

    PubMed Central

    2012-01-01

    Background The snail Neotricula aperta transmits Mekong schistosomiasis in southern Laos and Cambodia, with about 1.5 million people at risk of infection. Plans are under consideration for at least 12 hydroelectric power dams on the lower Mekong river and much controversy surrounds predictions of their environmental impacts. Unfortunately, there are almost no ecological data (such as long term population trend studies) available for N. aperta which could be used in impact assessment. Predictions currently assume that the impacts will be the same as those observed in Africa (i.e., a worsening of the schistosomiasis problem); however, marked ecological differences between the snails involved suggest that region specific models are required. The present study was performed as an initial step in providing data, which could be useful in the planning of water resource development in the Mekong. Snail population density records were analyzed for populations close to, and far downstream of, the Nam Theun 2 (NT2) project in Laos in order to detect any changes that might be attributable to impoundment. Results The population immediately downstream of NT2 and that sampled 400 km downstream in Thailand both showed a long term trend of slow growth from 1992 to 2005; however, both populations showed a marked decline in density between 2005 and 2011. The decline in Thailand was to a value significantly lower than that predicted by a linear mixed model for the data, whilst the population density close to NT2 fell to undetectable levels in 2011 from densities of over 5000 m-2 in 2005. The NT2 dam began operation in 2010. Conclusions The impact of the NT2 dam on N. aperta population density could be more complex than first thought and may reflect the strict ecological requirements of this snail. There was no indication that responses of N. aperta populations to dam construction are similar to those observed with Bulinus and Schistosoma haematobium in Africa, for example. In view

  1. Field and remote sensing for findings on the functions and evolutions of deltas

    NASA Astrophysics Data System (ADS)

    Taramelli, A.; Valentini, E.

    2013-12-01

    erosion rates) using new monitoring techniques such as satellite remote sensing shows to be a specific added value that could be used for simulations over varying time scales and it should be considered as a potential ';add in' for an integrated management approach that could be exported in major delta (i.e. Mekong).

  2. Greenhouse Gas Emissions within Seasonally Flooded Tropical River Deltas

    NASA Astrophysics Data System (ADS)

    Salvador, A. K.; Schaefer, M.; Roberts, K. A.; Fendorf, S. E.; Benner, S. G.

    2015-12-01

    Soils contain the largest terrestrial carbon pool on Earth, and approximately one-third of soil carbon is stored in the tropics. Gas exchange between soil and the atmosphere occurs largely as a result of microbial degradation (mineralization) of organic carbon. The rate of soil organic matter (SOM) mineralization is determined by a combination of climatic factors and soil ecosystem properties, which dictate the dominant metabolic pathway(s) within soil at a given time; major changes in metabolic rate are particularly pronounced between aerobic and anaerobic mineralization. Here we assessed the impact of soil moisture, a major factor determining soil anaerobiosis, on greenhouse gas fluxes in a tropical, seasonally flooded wetland in the Mekong Delta. We monitored CO2, CH4, and N2O gas fluxes, porewater chemistry, and soil moisture content in a seasonal wetland. Additionally, we collected wetland soil cores (10 cm diameter) and manipulated them in the laboratory, allowing us to control soil moisture and drying rates, and to simulate multiple periods of wetting and drying. During drying, CH4 fluxes within the wetland initially increase to a maximum before decreasing as soil moisture decreases and oxygen diffusion into the soil increases. Maximum CH4 fluxes vary with moisture content, but the wettest sites produced fluxes >1000 mg C m-2 d-1 for short periods of time. As drying continues, CH4 fluxes decrease to nearly zero, and N2O fluxes begin to increase to ~3 mg N m-2 d-1 but do not appear to have reached a maximum before sampling ceased. Gas flux from soil core incubations (n=5) exhibit trends and values similar to field measurements. CH4 fluxes initially increase and reach >1000 mg C m-2 d-1 in cores while N2O fluxes reach up to 10 mg N m-2 d-1 and decrease with continued drying. CO2 fluxes in both field and laboratory are sustained until near desiccated conditions. Seasonal wetlands are characteristic of large tropical deltas. Our findings provide a means to

  3. [Tapeworm fauna of gallinaceans (Galliformes) of Vietnam].

    PubMed

    Nguen Thi, K y; Dubinina, M N

    1978-01-01

    131 specimens of 3 species of Galliformes from Vietnam were investigated (Gallus gallus dom., G. g. jaboruillei, Francolinus pintadeanus and Lophora nycthemerus). In them 9 species of cestodes were found as follows: Davainea proglottina (Davainea, 1860), Cotugnia digonopora (Pasquale, 1890), Raillietina tetragona (Molin, 1858), R. echinobothrida (Megnin, 1880), Skrjabinia cesticillus (Molin, 1858), Paroniella tinguiana Tubangui et Masilungan, 1937, Amoebotaenia cuneata (Linstow, 1872), Echinolepis carioca (Magalhaes, 1898), Dilepidoides bauchei (Joyeux, 1924). In domestic hens there were found all 9 species of cestodes while in wild Galliformes--only 7, which are mentioned for them for the first time.

  4. Mackenzie River Delta, Canada

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Mackenzie River in the Northwest Territories, Canada, with its headstreams the Peace and Finley, is the longest river in North America at 4241 km, and drains an area of 1,805,000 square km. The large marshy delta provides habitat for migrating Snow Geese, Tundra Swans, Brant, and other waterfowl. The estuary is a calving area for Beluga whales. The Mackenzie (previously the Disappointment River) was named after Alexander Mackenzie who travelled the river while trying to reach the Pacific in 1789.

    The image was acquired on August 4, 2005, covers an area of 55.8 x 55.8 km, and is located at 68.6 degrees north latitude, 134.7 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  5. Colorado River Delta

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Colorado River ends its 2330 km journey in the Gulf of Mexico in Baja California. The heavy use of the river as an irrigation source for the Imperial Valley has dessicated the lower course of the river in Mexico such that it no longer consistently reaches the sea. Prior to the mid 20th century, the Colorado River Delta provided a rich estuarine marshland that is now essentially desiccated, but nonetheless is an important ecological resource.

    The image was acquired May 29, 2006, covers an area of 44.3 x 57.5 km, and is located at 32.1 degrees north latitude, 115.1 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  6. Forest transition in Vietnam and displacement of deforestation abroad

    PubMed Central

    Meyfroidt, Patrick; Lambin, Eric F.

    2009-01-01

    In some countries across the globe, tropical forest cover is increasing. The national-scale reforestation of Vietnam since 1992 is assumed to contribute to this recovery. It is achieved, however, by the displacement of forest extraction to other countries on the order of 49 (34–70) M m3, or ≈39% of the regrowth of Vietnam's forests from 1987 to 2006. Approximately half of wood imports to Vietnam during this period were illegal. Leakage due to policies restricting forest exploitation and displacement due to growing domestic consumption and exports contributed respectively to an estimated 58% and 42% of total displacement. Exports of wood products from Vietnam also grew rapidly, amounting to 84% of the displacement, which is a remarkable feature of the forest transition in Vietnam. Attribution of the displacement and corresponding forest extraction to Vietnam, the source countries or the final consumers is thus debatable. Sixty-one percent of the regrowth in Vietnam was, thus, not associated with displacement abroad. Policies allocating credits to countries for reducing deforestation and forest degradation should monitor illegal timber trade and take into account the policy-induced leakage of wood extraction to other countries. PMID:19805270

  7. Using Shoreline Video Assessment for coastal planning and restoration in the context of climate change in Kien Giang, Vietnam

    NASA Astrophysics Data System (ADS)

    Van Cuong, Chu; Russell, Michael; Brown, Sharon; Dart, Peter

    2015-06-01

    Kien Giang, bordering Cambodia in the Mekong River Delta, is one of the two most vulnerable provinces in the region to coastal erosion and flooding. Coastal protection can conflict with current land use and economic development activities. The conditions of the mangrove forest and mainland coastline of the Kien Giang province were assessed using the Shoreline Video Assessment Method (SVAM) backed up with information from satellite images. Half of the 206 km Kien Giang coastline has been eroded or is being eroded. Protective mangrove forests naturally occurred in 74% of the coastline but have been under threat from illegal cutting, erosion and coastal retreat. Accurate information on the state of the coastline and mangrove forest health provided invaluable data for developing a new coastal rehabilitation plan to guard against future sea level rise. In contrast to the current boundary management of land and natural resources, this plan divided the provincial coastline into 19 sections based on the landscape condition and exposure to erosion. Priority strategic actions for erosion management, mangrove restoration and sustainable livelihood development for local communities for each section of coast were developed based on an integrated cross sectoral approach and practical experience in the Conservation and Development of the Kien Giang Biosphere Reserve Project.

  8. Evaluation and application of newest GPM product with a distributed hydrological model at Mekong River basin

    NASA Astrophysics Data System (ADS)

    Wang, W.; Lu, H.; Sothea, K.

    2015-12-01

    Precipitation is a key input variable for a hydrological model. In this study, the newest released satellite-based precipitation product-Global Precipitation Measurement (GPM) IMERGE data is evaluated with a distributed hydrological model-Geomorphology Based Hydrological Model (GBHM) over the Mekong River Basin(MRB), which is the most important trans boundary river in Southeast Asia. Compared with Tropical Rainfall Measuring Mission (TRMM), GPM IMERGE has a higher temporal and spatial resolution (0.1°, 30mins). Firstly, a comparison between GPM IMERGE and TRMM 3B42 is carried out at grids during 2014/3/12-10/31 at MRB. It is found that, GPM IMERGE stays quite consistent with TRMM, but GPM is more sensitive to small rainfall events especially during dry seasons, which means GPM may have a better performance in dry seasons. Then GBHM is set up and calibrated at MRB, and the model is driven by GPM IMERGE and TRMM 3B42 respectively to simulate hydrology cycle between Chiang Saen and Krait, in order to remove the influences of dam operation in upstream. The simulated streamflow is compared against the observed daily time series at five gauges on mainstream. Generally, the simulated streamflow driven by GPM is closer to observation at gauges located downstream while those driven by TRMM 3B42 have a better performance at upstream gauges. On the other hand these two results stay agreement with each other and both of them have a quite good performance with Nash-Sutcliffe efficiency higher than 0.75 and relative bias less than 10%. This study demonstrates that for daily scale application, TRMM and GPM have almost the same performance. But GPM is more promising to be applied at fine temporal and spatial scales owing to its advantage of finer temporal and spatial resolution and ability to catch small rainfall events.

  9. Linking ecology to hydrology and geomorphology using river reach classification for the Greater Mekong Region

    NASA Astrophysics Data System (ADS)

    Ouelette Dallaire, Camille; Lehner, Bernhard

    2016-04-01

    Large-scale development projects, such as hydropower dams, in the Greater Mekong Region (GMR) are putting high pressure on freshwater resources. Environmental impact assessments are needed in the region to understand the possible impacts of these projects. These assessments often require biodiversity data that can be costly to acquire both in terms of time and money. It is often assumed that river or ecosystem classes, based on geo-physical characteristics, can be used as biodiversity proxies in large scale assessments to account for a lack of biodiversity data. However, there has been little research to compare the spatial distribution of river classes and fish species. It is unclear how well river classes are able to represent the distribution of fish and, more generally, biodiversity. To address this question, a set of two classifications were compared to a newly available dataset of fish species distribution in the GMR (Allen et al., 2012). The classifications were derived from two different methods to test which could potentially better represent fish assemblages. The first classification is derived using regional expert knowledge and the second using K-mean analysis. Both are using the same geophysical datasets. The two datasets were used in a Redundancy Analysis (RDA) to calculate which proportion of the variability in the fish species data can be explained by the river classes. The RDA resulted in R2 of 0.44 for the supervised classification and 0.41for the statistical classification, showing a moderate correlation between the datasets. Based on these results, using river classes as biodiversity proxy is deemed reasonable. However, some of the variability in the distribution of fish species cannot be related simply to geophysical factors. River classes may capture different elements such as unique habitats and associated, possibly unknown, endemic species that indices based only on biological data do not. Hence, river classes can be a good alternative and

  10. Current status of arsenic exposure and social implication in the Mekong River basin of Cambodia.

    PubMed

    Phan, Kongkea; Kim, Kyoung-Woong; Huoy, Laingshun; Phan, Samrach; Se, Soknim; Capon, Anthony Guy; Hashim, Jamal Hisham

    2016-06-01

    To evaluate the current status of arsenic exposure in the Mekong River basin of Cambodia, field interview along with urine sample collection was conducted in the arsenic-affected area of Kandal Province, Cambodia. Urine samples were analyzed for total arsenic concentrations by inductively coupled plasma mass spectrometry. As a result, arsenicosis patients (n = 127) had As in urine (UAs) ranging from 3.76 to 373 µg L(-1) (mean = 78.7 ± 69.8 µg L(-1); median = 60.2 µg L(-1)). Asymptomatic villagers (n = 108) had UAs ranging from 5.93 to 312 µg L(-1) (mean = 73.0 ± 52.2 µg L(-1); median = 60.5 µg L(-1)). About 24.7 % of all participants had UAs greater than 100 µg L(-1) which indicated a recent arsenic exposure. A survey found that females and adults were more likely to be diagnosed with skin sign of arsenicosis than males and children, respectively. Education level, age, gender, groundwater drinking period, residence time in the village and amount of water drunk per day may influence the incidence of skin signs of arsenicosis. This study suggests that residents in Kandal study area are currently at risk of arsenic although some mitigation has been implemented. More commitment should be made to address this public health concern in rural Cambodia.

  11. Surveillance on chronic arsenic exposure in the Mekong River basin of Cambodia using different biomarkers.

    PubMed

    Phan, Kongkea; Sthiannopkao, Suthipong; Kim, Kyoung-Woong

    2011-12-01

    Thousands of Cambodia populations are currently at high risks of both toxic and carcinogenic effects through drinking arsenic-rich groundwater. In order to determine and assess the use of arsenic contents in different biological samples as biomarkers of chronic arsenic exposure from drinking arsenic-rich groundwater in Cambodia, individual scalp hair, fingernail and toenail were collected from three different provinces in the Mekong River basin of Cambodia. After washing and acid-digestion, digestate was analyzed for total arsenic by an inductively coupled plasma mass spectrometry. Chemical analysis of the acid-digested hair revealed that among 270 hair samples cut from Kandal, 78.1% had arsenic content in scalp hair (As(h)) greater than the typical As(h) (1.00 μg g(-1)), indicating possible arsenic toxicity. Concurrently, 1.2% and 0.6% were found elevated in Kratie (n=84) and Kampong Cham (n=173), respectively. Similarly, the upper end of the ranges for arsenic contents in fingernail (As(fn)) and toenail (As(tn)) clipped from Kandal (fingernail n=241; toenail n=187) were higher than the normal arsenic content in nail (0.43-1.08 μg g(-1)), however, none was observed elevated in both Kratie (fingernail n=76, toenail n=42) and Kampong Cham (fingernail n=83; toenail n=52). Significant positive intercorrelations between groundwater arsenic concentration (As(w)), average daily dose (ADD) of arsenic, As(h), As(fn) and As(tn) suggest that As(h), As(fn) and As(tn) can be used as biomarkers of chronic arsenic exposure from drinking arsenic-rich groundwater, in which As(h) is more favorable than As(fn) and As(tn) due to the ease of sample processing and analytical measurements, respectively.

  12. Monitoring agricultural drought in the Lower Mekong Basin using MODIS NDVI and land surface temperature data

    NASA Astrophysics Data System (ADS)

    Son, N. T.; Chen, C. F.; Chen, C. R.; Chang, L. Y.; Minh, V. Q.

    2012-08-01

    Drought is a complex natural phenomenon, and its impacts on agriculture are enormous. Drought has been a prevalent concern for farmers in the Lower Mekong Basin (LMB) over the last decades; thus, monitoring drought is important for water planning and management to mitigate impacts on agriculture in the region. This study explored the applicability of monthly MODIS normalized difference vegetation index (NDVI) and land surface temperature (LST) data for agricultural drought monitoring in LMB in the dry season from November 2001 to April 2010. The data were processed using the temperature vegetation dryness index (TVDI), calculated by parameterizing the relationship between the MODIS NDVI and LST data. The daily volumetric surface soil moisture from the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and monthly precipitation from the Tropical Rainfall Measuring Mission (TRMM) were collected and used for verification of the results. In addition, we compared the efficiency of TVDI with a commonly used drought index, the crop water stress index (CWSI), derived from the MODIS LST alone. The results achieved from comparisons between TVDI and AMSR-E soil moisture data indicated acceptable correlations between the two datasets in most cases. There was close agreement between TVDI and TRMM precipitation data through the season, indicating that TVDI was sensitive to precipitation. The TVDI compared to CWSI also yielded close correlations between both datasets. The TVDI was, however, more sensitive to soil moisture stress than CWSI. The results archived by analysis of TVDI indicated that the moderate and severe droughts were spatially scattered over the region from November to March, but more extensive in northeast Thailand and Cambodia. The larger area of severe drought was especially observed for the 2003-2006 dry seasons compared to other years. The results achieved from this study could be important for drought warnings and irrigation scheduling.

  13. The Kriging Method for Combining Multi-Mission Altimetry over the Mekong River

    NASA Astrophysics Data System (ADS)

    Boergens, Eva; Buhl, Sven; Dettmering, Denise; Schwatke, Christian; Seitz, Florian

    2016-08-01

    In recent years, water level variations of inland water bodies such as lakes, reservoirs, and rivers measured by satellite altimetry got well established. Most inland water level time series are only assembled from measurements of one pass of one single satellite mission. Only a few multi-mission approaches combine different missions and passes over lakes and reservoirs in order to increase the accuracy and temporal resolution of the time series. This is possible because the lake surface can be considered to be constant everywhere at a given time. However, it is not possible so far to combine different altimeter missions and passes over rivers.We developed a new methodology to combine altimetry data from different missions in a statistical robust way along the river. The methodology is based on kriging which is an interpolation method originating from geostatistics. We expanded the concept to spatio-temporal kriging along the river. The interpolation is a weighted average of available measurements based on empirical correlations not only in the spatial domain but in the temporal domain as well. The higher the correlation, the more weight a measurement obtains in the average. With this approach we are able to combine data not only along the river at a given time or a given location but also data at another location at another time. We developed a statistical model to describe the dependencies between different measurement locations; a prerequisite for the kriging algorithm.We employed the kriging method on altimeter measurements of the Mekong River in South-east Asia. Data of the Envisat, Envisat EM, Jason-2, and SARAL/AltiKa mission were incorperated. With this we are able to achieve a higher temporal resolution time series at any given location. The resulting estimated time series are compared to in-situ data from gauging stations along the river and show a high agreement with these.

  14. Observed river discharge changes due to hydropower operations in the Upper Mekong Basin

    NASA Astrophysics Data System (ADS)

    Räsänen, Timo A.; Someth, Paradis; Lauri, Hannu; Koponen, Jorma; Sarkkula, Juha; Kummu, Matti

    2017-02-01

    The Upper Mekong Basin is undergoing extensive hydropower development and its largest dams have recently become operational. Hydropower is built to improve the regional energy supply, but at the same time, it has considerable transboundary impacts on downstream discharge regime and further on aquatic ecosystems, riparian livelihoods and food security. Despite the transboundary significance of the impacts, there is no public information on the hydropower operations or on the already observed downstream discharge impacts since the completion of the largest dams. Therefore, in this study we assess the discharge changes using observed river discharge data and a distributed hydrological model over the period of 1960-2014. Our findings indicate that the hydropower operations have considerably modified the river discharges since 2011 and the largest changes were observed in 2014. According to observed and simulated discharges, the most notable changes occurred in northern Thailand (Chiang Saen) in March-May 2014 when the discharge increased by 121-187% and in July-August 2014 when the discharge decreased by 32-46% compared to average discharges. The respective changes in Cambodia (Kratie) were 41-74% increase in March-May 2014 and 0-6% decrease in July-August 2014 discharges. The earlier model-based predictions of the discharge changes are well in line with the observed changes, although observed changes are partly larger. The discharge impacts are expected to vary from year to year depending on hydropower operations. Altogether, the results highlight the need for strong transboundary cooperation for managing the downstream impacts.

  15. Land Use and Water Quality Along a Mekong Tributary in Northern Lao P.D.R.

    NASA Astrophysics Data System (ADS)

    Ribolzi, Olivier; Cuny, Juliette; Sengsoulichanh, Phonexay; Mousquès, Claire; Soulileuth, Bounsamai; Pierret, Alain; Huon, Sylvain; Sengtaheuanghoung, Oloth

    2011-02-01

    Improving access to clean water has the potential to make a major contribution toward poverty reduction in rural communities of Lao P.D.R. This study focuses on stream water quality along a Mekong basin tributary, the Houay Xon that flows within a mountainous, mosaic land-use catchment of northern Lao P.D.R. To compare direct water quality measurements to the perception of water quality within the riparian population, our survey included interviews of villagers. Water quality was found to vary greatly depending on the location along the stream. Overall, it reflected the balance between the stream self-cleaning potential and human pressure on the riparian zone: (i) high bacteria and suspended load levels occurred where livestock are left to free-range within the riparian zone; (ii) very low oxygen content and high bacteriological contamination prevailed downstream from villages; (iii) high concentrations of bacteria were consistently observed along urbanized banks; (iv) low oxygen content were associated with the discharge of organic-rich wastewater from a small industrial plant; (v) very high suspended load and bacteria levels occurred during flood events due to soil erosion from steep cultivated hill slopes. Besides these human induced pollutions we also noted spontaneous enrichments in metals in wetland areas fed by dysoxic groundwater. These biophysical measurements were in agreement with the opinions expressed by the majority of the interviewees who reported poor and decreasing water quality in the Houay Xon catchment. Based on our survey, we propose recommendations to improve or maintain stream water quality in the uplands of northern Lao P.D.R.

  16. Perspective: Towards environmentally acceptable criteria for downstream fish passage through mini hydro and irrigation infrastructure in the Lower Mekong River Basin

    SciTech Connect

    Baumgartner, Lee J.; Daniel Deng, Z.; Thorncraft, Garry; Boys, Craig A.; Brown, Richard S.; Singhanouvong, Douangkham; Phonekhampeng, Oudom

    2014-01-01

    Tropical rivers have high annual discharges optimal for hydropower and irrigation development. The Mekong River is one of the largest tropical river systems, supporting a unique mega-diverse fish community. Fish are an important commodity in the Mekong, contributing a large proportion of calcium, protein, and essential nutrients to the diet of the local people and providing a critical source of income for rural households. Many of these fish migrate not only upstream and downstream within main-channel habitats but also laterally into highly productive floodplain habitat to both feed and spawn. Most work to date has focused on providing for upstream fish passage, but downstream movement is an equally important process to protect. Expansion of hydropower and irrigation weirs can disrupt downstream migrations and it is important to ensure that passage through regulators or mini hydro systems is not harmful or fatal. Many new infrastructure projects (<6 m head) are proposed for the thousands of tributary streams throughout the Lower Mekong Basin and it is important that designs incorporate the best available science to protect downstream migrants. Recent advances in technology have provided new techniques which could be applied to Mekong fish species to obtain design criteria that can facilitate safe downstream passage. Obtaining and applying this knowledge to new infrastructure projects is essential in order to produce outcomes that are more favorable to local ecosystems and fisheries.

  17. Proposed Training Plan to Improve Building Energy Efficiency in Vietnam

    SciTech Connect

    Yu, Sha; Evans, Meredydd

    2013-01-01

    Vietnam has experienced fast growth in energy consumption in the past decade, with annual growth rate of over 12 percent. This is accompanied by the fast increase in commercial energy use, driven by rapid industrialization, expansion of motorized transport, and increasing energy use in residential and commercial buildings. Meanwhile, Vietnam is experiencing rapid urbanization at a rate of 3.4 percent per year; and the majority of the growth centered in and near major cities such as Hanoi and Ho Chi Minh City. This has resulted in a construction boom in Vietnam.

  18. 77 FR 64471 - Circular Welded Carbon-Quality Steel Pipe From the Socialist Republic of Vietnam: Final Negative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-22

    ... Vietnam: Final Negative Countervailing Duty Determination AGENCY: Import Administration, International... welded carbon-quality steel pipe (``circular welded pipe'') from the Socialist Republic of Vietnam (``Vietnam''). DATES: Effective Date: October 22, 2012. FOR FURTHER INFORMATION CONTACT: Christopher...

  19. Characterizing and Exploring the Implications of Maritime Irregular Warfare

    DTIC Science & Technology

    2012-01-01

    on rivers for mobility. However, we included them in our analysis because they entail the use of maritime capabilities and therefore may inform...forces from flowing by sea between North and South Vietnam. Operation Game Warden was a riverine operation that used river -patrol boats to disrupt VC...supply traffic on the major rivers of the Mekong Delta. Both Market Time and Game Warden were external operations, as defined in Chapter Two. The

  20. Thermometric well testing on the Vietnam offshore

    SciTech Connect

    San, T.N.; Shtyrlin, V.F.; Vakhitov, G.G.; Loi, L.M.; Listengarten, L.; Hien, D.L.

    1994-12-31

    It is impossible to control and adjust an oil and gas field development without determining the flow intervals of production wells. For that it is preferable to get production profiles by using the downhole flowmeter. There are, however, some main restrictions for wide-spread application of them on the offshore of Vietnam as follows: the flowmeter spinner velocity cannot indicate correctly in the open hole wells having a nonuniform diameter; it is unable to carry out in the case when the tubing shoe is lower than top formation on 300--500m. In this paper, the authors present a summary of temperature profile method to determine the flowing and intaking intervals of wells drilled in basement of the White Tiger Field on Vietnam offshore. For the last 2 years more than 30 wells were surveyed by this method in the above mentioned conditions. This paper presents the theory and practice of well temperature profile surveys, the concrete examples of data interpretation using the software Oiltest.

  1. Magnetic minerals in three Asian rivers draining into the South China Sea: Pearl, Red, and Mekong Rivers

    NASA Astrophysics Data System (ADS)

    Kissel, Catherine; Liu, Zhifei; Li, Jinhua; Wandres, Camille

    2016-05-01

    The use of the marine sedimentary magnetic properties, as tracers for changes in precipitation rate and in oceanic water masses transport and exchanges, implies to identify and to characterize the different sources of the detrital fraction. This is of particular importance in closed and/or marginal seas such as the South China Sea. We report on the magnetic properties of sedimentary samples collected in three main Asian rivers draining into the South China Sea: the Pearl, Red, and Mekong Rivers. The geological formations as well as the present climatic conditions are different from one catchment to another. The entire set of performed magnetic analyses (low-field magnetic susceptibility, ARM acquisition and decay, IRM acquisition and decay, back-field acquisition, thermal demagnetization of three-axes IRM, hysteresis parameters, FORC diagrams, and low-temperature magnetic measurements) allow us to identify the magnetic mineralogy and the grain-size distribution when magnetite is dominant. Some degree of variability is observed in each basin, illustrating different parent rocks and degree of weathering. On average it appears that the Pearl River is rich in magnetite along the main stream while the Mekong River is rich in hematite. The Red River is a mixture of the two. Compared to clay mineral assemblages and major element contents previously determined on the same samples, these new findings indicate that the magnetic fraction brings complementary information of great interest for environmental reconstructions based on marine sediments from the South China Sea.

  2. Artificial delta growth

    NASA Astrophysics Data System (ADS)

    Mikeš, Daniel

    2010-05-01

    A deltaic sedimentary system has a point source; sediment is carried over the delta plain by distributary channels away from the point source and deposited at the delta front by distributary mouth bars. The established methods to describe such a sedimentary system are "bedding analysis", "facies analysis", and "basin analysis". We shall call the ambient conditions "input" and the rock record "output". There exist a number of methods to deduce input from output, e.g. "Sequence stratigraphy" (a.o. Vail et al. 1977, Catuneanu et al. 2009), "Shoreline trajectory" (a.o. Helland-Hansen & Martinsen 1996, Helland-Hansen & Hampson 2009) on the one hand and the complex use of established techniques on the other (a.o. Miall & Miall 2001, Miall & Miall 2002). None of these deductive methods seems to be sufficient. I claim that the common errors in all these attempts are the following: (1) a sedimentary system is four-dimensional (3+1) and a lesser dimensional analysis is insufficient; (2) a sedimentary system is complex and any empirical/deductive analysis is non-unique. The proper approach to the problem is therefore the theoretical/inductive analysis. To that end we performed six scenarios of a scaled version of a passive margin delta in a flume tank. The scenarios have identical stepwise tectonic subsidence and semi-cyclic sealevel, but different supply curves, i.e. supply is: constant, highly-frequent, proportional to sealevel, inversely proportional to sealevel, lagging to sealevel, ahead of sealevel. The preliminary results are indicative. Lobe-switching occurs frequently and hence locally sedimentation occurs shortly and hiatuses are substantial; therefore events in 2D (+1) cross-sections don't correlate temporally. The number of sedimentary cycles disequals the number of sealevel cycles. Lobe-switching and stepwise tectonic subsidence cause onlap/transgression. Erosional unconformities are local diachronous events, whereas maximum flooding surfaces are regional

  3. Exploring Vietnam: A Multiple Intelligence Portfolio of Learning.

    ERIC Educational Resources Information Center

    Hoover, Linda A.; Taylor, Randall

    1998-01-01

    Provides guidelines for implementing portfolios in the social studies classroom that focus on the Vietnam era and incorporate Howard Gardner's multiple intelligences. Outlines the portfolio project, lists eleven portfolio components, and addresses the intelligence of each. (CMK)

  4. Local environmental predictors of cholera in Bangladesh and Vietnam.

    PubMed

    Emch, Michael; Feldacker, Caryl; Yunus, Mohammad; Streatfield, Peter Kim; DinhThiem, Vu; Canh, Do Gia; Ali, Mohammad

    2008-05-01

    Environmental factors have been shown to be related to cholera and thus might prove useful for prediction. In Bangladesh and Vietnam, temporal cholera distributions are related to satellite-derived and in-situ environmental time series data in order to examine the relationships between cholera and the local environment. Ordered probit models examine associations in Bangladesh; probit models examine associations at 2 sites in Vietnam. Increases in ocean chlorophyll concentration are related to an increased magnitude of cholera in Bangladesh. Increases in sea surface temperature are most influential in Hue, Vietnam, whereas increases in river height have a significant role in Nha Trang, Vietnam. Cholera appearance and epidemic magnitude are related to the local environment. Local environmental parameters have consistent effects when cholera is regular and more prevalent in endemic settings, but in situations where cholera epidemics are rare there are differential environmental effects.

  5. Post-Traumatic Stress Disorder and the Canadian Vietnam Veteran

    DTIC Science & Technology

    1989-03-30

    Documentation Page, DD Form 1473 (is)(is not) attached. Title Post - Traumatic Stress Disorder and the Canadian Vietnam Veteran Author(s) Robert H. Stretch...EDITIONS WILL BE USED U. Post - Traumatic Stress Disorder and the Canadian Vietnam Veteran MAJ Robert H. Stretch, Ph.D. U.S. Army Medical R&D Command... Post - Traumatic Stress Disorder (PTSD). PTSD results from exposure to trauma that is generally outside the range of normal human experience. It is

  6. Dioxin in Vietnam: fighting a legacy of war.

    PubMed

    Booker, S M

    2001-03-01

    Singapore was the site of an East-West convergence over the week of 27 November-1 December 2000. At the behest of their respective governments, scientists from the United States and Vietnam came together for what promises to be the first of many meetings. Their mission: to explore the possibility of launching a joint research program to study the human and environmental health effects resulting from spraying Agent Orange and other herbicides during the Vietnam War.

  7. Vietnam’s Drive to Modernize Militarily - Causes and Implications

    DTIC Science & Technology

    2014-12-01

    Jon Grevatt, “IHS Jane’s - Vietnam Buys Twin Otter Amphibians ,” May 7, 2010, https://janes.ihs.com.libproxy.nps.edu/CustomPages/Janes/DisplayPage.aspx...ItemId=+++1145015&Pubabbrev=JDIN. ———. “IHS Jane’s - Vietnam Buys Twin Otter Amphibians ,” May 7, 2010. https://janes.ihs.com.libproxy.nps.edu/CustomPages

  8. Supersonic aerodynamics of delta wings

    NASA Technical Reports Server (NTRS)

    Wood, Richard M.

    1988-01-01

    Through the empirical correlation of experimental data and theoretical analysis, a set of graphs has been developed which summarize the inviscid aerodynamics of delta wings at supersonic speeds. The various graphs which detail the aerodynamic performance of delta wings at both zero-lift and lifting conditions were then employed to define a preliminary wing design approach in which both the low-lift and high-lift design criteria were combined to define a feasible design space.

  9. Design and methods of the national Vietnam veterans longitudinal study.

    PubMed

    Schlenger, William E; Corry, Nida H; Kulka, Richard A; Williams, Christianna S; Henn-Haase, Clare; Marmar, Charles R

    2015-09-01

    The National Vietnam Veterans Longitudinal Study (NVVLS) is the second assessment of a representative cohort of US veterans who served during the Vietnam War era, either in Vietnam or elsewhere. The cohort was initially surveyed in the National Vietnam Veterans Readjustment Study (NVVRS) from 1984 to 1988 to assess the prevalence, incidence, and effects of post-traumatic stress disorder (PTSD) and other post-war problems. The NVVLS sought to re-interview the cohort to assess the long-term course of PTSD. NVVLS data collection began July 3, 2012 and ended May 17, 2013, comprising three components: a mailed health questionnaire, a telephone health survey interview, and, for a probability sample of theater Veterans, a clinical diagnostic telephone interview administered by licensed psychologists. Excluding decedents, 78.8% completed the questionnaire and/or telephone survey, and 55.0% of selected living veterans participated in the clinical interview. This report provides a description of the NVVLS design and methods. Together, the NVVRS and NVVLS constitute a nationally representative longitudinal study of Vietnam veterans, and extend the NVVRS as a critical resource for scientific and policy analyses for Vietnam veterans, with policy relevance for Iraq and Afghanistan veterans.

  10. United States national security policy making and Vietnam

    SciTech Connect

    Davidson, M.W.

    1985-01-01

    The United States failed to achieve its goals in waging a war in Vietnam. This thesis endeavors to show that this failure was due to errors in the formulation of American national security policy regarding Vietnam. The policy making process went astray, at least in part, due to a narrowing of the role of senior military officers as national security policy makers. The restricted role of senior officers as national security policy makers adversely affected American policy formulation regarding Vietnam. The United States response to the coup against Diem in 1963 and the deployment of conventional American forces to ground combat in Vietnam, in 1965 were undertaken without a clear recognition of the considerable costs of the commitments being assumed. Senior military officers had prompted such a recognition in similar previous crises but were not in a policy making position to do so concerning Vietnam. The policymaking input that was absent was ethical counsel of a fundamental nature. Clausewitz viewed the mortality of a war as being embodied in the national will to fight that war. The absence of an accurate appreciation of the costs of a military solution in Vietnam denied civilian officials a critical policy making factor and contributed significantly to the defeat of the American purpose there.

  11. Evolution and phylogeographic dissemination of endemic porcine picornaviruses in Vietnam

    PubMed Central

    Lu, Lu; Van Dung, Nguyen; Bryant, Juliet E.; Carrique-Mas, Juan; Van Cuong, Nguyen; Anh, Pham Honh; Rabaa, Maia A.; Baker, Stephen; Simmonds, Peter; Woolhouse, Mark E.

    2016-01-01

    Members of the Picornaviridae are important and often zoonotic viruses responsible for a variety of human and animal diseases. However, the evolution and spatial dissemination of different picornaviruses circulating in domestic animals are not well studied. We examined the rate of evolution and time of origin of porcine enterovirus G (EV-G) and porcine kobuvirus species C lineages (PKV-C) circulating in pig farms in Vietnam and from other countries. We further explored the spatiotemporal spread of EV-G and PKV-C in Southwest Vietnam using phylogeographic models. Multiple types of EV-G are co-circulating in Vietnam. The two dominant EV-G types among isolates from Vietnam (G1 and G6) showed strong phylogenetic clustering. Three clades of PKV-C (PKV-C1-3) represent more recent introductions into Vietnam; PKV-C2 is closely related to PKV-C from Southwest China, indicating possible cross-border dissemination. In addition, high virus lineage migration rates were estimated within four districts in Dong Thap province in Vietnam for both EV-G types (G1, G6) and all PKV-C (C1-3) clades. We found that Chau Thanh district is a primary source of both EV-G and PKV-C clades, consistent with extensive pig trading in and out of the district. Understanding the evolution and spatial dissemination of endemic picornaviruses in pigs may inform future strategies for the surveillance and control of picornaviruses. PMID:27774295

  12. 77 FR 65712 - Circular Welded Carbon-Quality Steel Pipe From Vietnam; Termination of Investigation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-30

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Circular Welded Carbon-Quality Steel Pipe From Vietnam; Termination of Investigation AGENCY... investigation concerning circular welded carbon-quality steel pipe from Vietnam (investigation No....

  13. Molecular epidemiology of rabies virus in Vietnam (2006-2009).

    PubMed

    Nguyen, Anh K T; Nguyen, Dong V; Ngo, Giang C; Nguyen, Thu T; Inoue, Satoshi; Yamada, Akio; Dinh, Xuyen K; Nguyen, Dung V; Phan, Thao X; Pham, Bao Q; Nguyen, Hien T; Nguyen, Hanh T H

    2011-01-01

    This study was aimed at determining the molecular epidemiology of rabies virus (RABV) circulating in Vietnam. Intra vitam samples (saliva and cerebrospinal fluid) were collected from 31 patients who were believed to have rabies and were admitted to hospitals in northern provinces of Vietnam. Brain samples were collected from 176 sick or furious rabid dogs from all over the country. The human and canine samples were subjected to reverse transcription-polymerase chain reaction analysis. The findings showed that 23 patients tested positive for RABV. Interestingly, 5 rabies patients did not have any history of dog or cat bites, but they had an experience of butchering dogs or cats, or consuming their meat. RABV was also detected in 2 of the 100 sick dogs from slaughterhouses. Molecular epidemiological analysis of 27 RABV strains showed that these viruses could be classified into two groups. The RABVs classified into Group 1 were distributed throughout Vietnam and had sequence similarity with the strains from China, Thailand, Malaysia, and the Philippines. However, the RABVs classified into Group 2 were only found in the northern provinces of Vietnam and showed high sequence similarity with the strain from southern China. This finding suggested the recent influx of Group 2 RABVs between Vietnam and China across the border. Although the incidence of rabies due to circulating RABVs in slaughterhouses is less common than that due to dog bite, the national program for rabies control and prevention in Vietnam should include monitoring of the health of dogs meant for human consumption and vaccination for workers at dog slaughterhouses. Further, monitoring of and research on the circulating RABVs in dog markets may help to determine the cause of rabies and control the spread of rabies in slaughterhouses in Vietnam.

  14. The flood pulse as the underlying driver of vegetation in the largest wetland and fishery of the Mekong Basin.

    PubMed

    Arias, Mauricio E; Cochrane, Thomas A; Norton, David; Killeen, Timothy J; Khon, Puthea

    2013-11-01

    The Tonle Sap is the largest wetland in Southeast Asia and one of the world's most productive inland fisheries. The Mekong River inundates the Tonle Sap every year, shaping a mosaic of natural and agricultural habitats. Ongoing hydropower development, however, will dampen the flood pulse that maintains the Tonle Sap. This study established the current underlying relationship among hydrology, vegetation, and human use. We found that vegetation is strongly influenced by flood duration; however, this relationship was heavily distorted by fire, grazing, and rice cultivation. The expected flood pulse alteration will result in higher water levels during the dry season, permanently inundating existing forests. The reduction of the maximum flood extent will facilitate agricultural expansion into natural habitats. This study is the most comprehensive field survey of the Tonle Sap to date, and it provides fundamental knowledge needed to understand the underlying processes that maintain this important wetland.

  15. Schistura sexnubes, a new diminutive river loach from the upper Mekong basin, Yunnan Province, China (Teleostei: Cypriniformes: Nemacheilidae)

    PubMed Central

    Endruweit, Marco

    2014-01-01

    An ichthyofaunistic survey of Mekong tributaries in Lincang Prefecture, Yunnan Province, China yielded a new species of nemacheilid loach, herein described as Schistura sexnubes species nova. The new species is readily distinguishable from its congeners by the following combination of characters: 8+8 branched caudal fin rays, an incomplete lateral line, a dissociated caudal bar, a shallow caudal peduncle depth (7.6%−9.6% SL; respectively caudal peduncle 1.76−1.95 times longer than deep), a diminutive size of less than 50 mm SL, and no sexual dimorphism. A dorsocephalic pattern consisting of a black, forward directed V-shaped formation located between the nares, and a white, ovoid blotch on the upper operculum serves as an autapomorphy. PMID:24470455

  16. The DELTA Synchrotron Light Interferometer

    SciTech Connect

    Berges, U.

    2004-05-12

    Synchrotron radiation sources like DELTA, the Dortmund Electron Accelerator, a third generation synchrotron light source, need an optical monitoring system to measure the beam size at different points of the ring with high resolution and accuracy. These measurements also allow an investigation of the emittance of the storage ring, an important working parameter for the efficiency of working beamlines with experiments using the synchrotron radiation. The resolution limits of the different types of optical synchrotron light monitors at DELTA are investigated. The minimum measurable beamsize with the normal synchrotron light monitor using visible light at DELTA is about 80 {mu}m. Due to this a synchrotron light interferometer was built up and tested at DELTA. The interferometer uses the same beamline in the visible range. The minimum measurable beamsize is with about 8 {mu}m one order of magnitude smaller. This resolution is sufficient for the expected small vertical beamsizes at DELTA. The electron beamsize and emittance were measured with both systems at different electron beam energies of the storage ring. The theoretical values of the present optics are smaller than the measured emittance. So possible reasons for beam movements are investigated.

  17. 78 FR 35643 - Frozen Warmwater Shrimp from China, Ecuador, India, Indonesia, Malaysia, Thailand, and Vietnam...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-13

    ... COMMISSION Frozen Warmwater Shrimp from China, Ecuador, India, Indonesia, Malaysia, Thailand, and Vietnam..., Malaysia, Thailand, and Vietnam of frozen warmwater shrimp, provided for in subheadings 0306.17.00, 1605.21... found to be subsidized by the Governments of China, India, Malaysia, Thailand, and Vietnam and that...

  18. 77 FR 3737 - Steel Wire Garment Hangers From the Socialist Republic of Vietnam: Initiation of Countervailing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-25

    ... International Trade Administration Steel Wire Garment Hangers From the Socialist Republic of Vietnam: Initiation... concerning imports of steel wire garment hangers from the Socialist Republic of Vietnam (Vietnam) filed in... of Antidumping Duties on Steel Wire Garment Hangers from Taiwan and the Social Republic of...

  19. 76 FR 4292 - Certain Frozen Fish Fillets From the Socialist Republic of Vietnam: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-25

    ... International Trade Administration Certain Frozen Fish Fillets From the Socialist Republic of Vietnam...'') published in the Federal Register the antidumping duty order on certain frozen fish fillets from the Socialist Republic of Vietnam (``Vietnam''). See Notice of Antidumping Duty Order: Certain Frozen...

  20. 76 FR 20627 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-13

    ...-Market Economy Country Status In every case conducted by the Department involving Vietnam, Vietnam has been treated as a non-market (``NME'') country. In accordance with section 771(18)(C)(i) of the Act... NME countries. \\6\\ See Certain Frozen Fish Fillets From the Socialist Republic of Vietnam:...

  1. Treatment Failure of Dihydroartemisinin/Piperaquine for Plasmodium falciparum Malaria, Vietnam

    PubMed Central

    Phuc, Bui Quang; Duong, Tran Thanh; Dong, Le Than; Loi, Mai Anh; Ménard, Didier; Tarning, Joel; Bustos, Dorina; Ringwald, Pascal; Galappaththy, Gawrie Loku; Thieu, Nguyen Quang

    2017-01-01

    We conducted a study in Binh Phuoc, Vietnam, in 2015 on the therapeutic efficacy of dihydroartemisinin/piperaquine for Plasmodium falciparum malaria. A high number of treatment failures (14/40) was found, and piperaquine resistance in Vietnam was confirmed. A change in the malaria treatment policy for Vietnam is in process. PMID:28322709

  2. Stratification and the Emergence of the Postsecondary Private Education Sector in Vietnam

    ERIC Educational Resources Information Center

    Goyette, Kimberly Ann

    2012-01-01

    Vietnam has a strong public postsecondary education sector that has only recently begun to experience growth in nonpublic institutions. I investigate how the growth of nonpublic institutions may be related to stratification in Vietnam. I find that these institutions are more likely to serve more advantaged students from South Vietnam. Students pay…

  3. 3 CFR 8789 - Proclamation 8789 of March 29, 2012. Vietnam Veterans Day

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Vietnam War is a story of service members of different backgrounds, colors, and creeds who came together... Vietnam. Yet, in one of the war’s most profound tragedies, many of these men and women came home to be..., ceremonies, and activities that commemorate the 50-year anniversary of the Vietnam War. IN WITNESS WHEREOF,...

  4. Making History Come Alive with the Nonfiction Literature of the Vietnam War.

    ERIC Educational Resources Information Center

    Johannessen, Larry R.

    2003-01-01

    Considers student response to nonfiction Vietnam War literature and discusses why students should study Vietnam War nonfiction. Presents strategies for teaching nonfiction Vietnam War literature. Presents follow-up research and writing activities that are designed to enable students to connect reading, writing, and thinking. Concludes that the…

  5. 78 FR 10210 - Utility Scale Wind Towers From China and Vietnam

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-13

    ... COMMISSION Utility Scale Wind Towers From China and Vietnam Determinations On the basis of the record \\1... with material injury by reason of imports of utility scale wind towers from China and Vietnam, provided... of imports of utility scale wind towers from China and Vietnam. Commissioner Dean A....

  6. 77 FR 9701 - Steel Wire Garment Hangers From Taiwan And Vietnam

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-17

    ... COMMISSION Steel Wire Garment Hangers From Taiwan And Vietnam Determinations On the basis of the record \\1... injured by reason of imports from Taiwan and Vietnam of steel wire garment hangers, provided for in... the United States at less than fair value (LTFV) and steel wire garment hangers from Vietnam that...

  7. 77 FR 76170 - Presumption of Exposure to Herbicides for Blue Water Navy Vietnam Veterans Not Supported

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-26

    ... AFFAIRS Presumption of Exposure to Herbicides for Blue Water Navy Vietnam Veterans Not Supported ACTION... Veterans were exposed to Agent Orange-associated herbicides during the Vietnam War. After careful review of... establishing a presumption of exposure to herbicides for Blue Water Navy Vietnam Veterans. VA will continue...

  8. 75 FR 60730 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Initiation of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-01

    ... International Trade Administration Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam... antidumping duty order on certain frozen warmwater shrimp (``shrimp'') from the Socialist Republic of Vietnam...: Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam, 70 FR 5152 (February 1,...

  9. 38 CFR 3.313 - Claims based on service in Vietnam.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Claims based on service... Evaluations; Service Connection § 3.313 Claims based on service in Vietnam. (a) Service in Vietnam. Service in Vietnam includes service in the waters offshore, or service in other locations if the conditions...

  10. 38 CFR 3.313 - Claims based on service in Vietnam.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Claims based on service... Evaluations; Service Connection § 3.313 Claims based on service in Vietnam. (a) Service in Vietnam. Service in Vietnam includes service in the waters offshore, or service in other locations if the conditions...

  11. 38 CFR 3.313 - Claims based on service in Vietnam.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Claims based on service... Evaluations; Service Connection § 3.313 Claims based on service in Vietnam. (a) Service in Vietnam. Service in Vietnam includes service in the waters offshore, or service in other locations if the conditions...

  12. 38 CFR 3.313 - Claims based on service in Vietnam.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Claims based on service... Evaluations; Service Connection § 3.313 Claims based on service in Vietnam. (a) Service in Vietnam. Service in Vietnam includes service in the waters offshore, or service in other locations if the conditions...

  13. 38 CFR 21.5020 - Post-Vietnam era veterans' educational assistance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Post-Vietnam era veterans... AFFAIRS (CONTINUED) VOCATIONAL REHABILITATION AND EDUCATION Post-Vietnam Era Veterans' Educational Assistance Under 38 U.S.C. Chapter 32 General § 21.5020 Post-Vietnam era veterans' educational...

  14. 38 CFR 21.5020 - Post-Vietnam era veterans' educational assistance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2013-07-01 2013-07-01 false Post-Vietnam era veterans... AFFAIRS (CONTINUED) VOCATIONAL REHABILITATION AND EDUCATION Post-Vietnam Era Veterans' Educational Assistance Under 38 U.S.C. Chapter 32 General § 21.5020 Post-Vietnam era veterans' educational...

  15. 38 CFR 21.5020 - Post-Vietnam era veterans' educational assistance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2012-07-01 2012-07-01 false Post-Vietnam era veterans... AFFAIRS (CONTINUED) VOCATIONAL REHABILITATION AND EDUCATION Post-Vietnam Era Veterans' Educational Assistance Under 38 U.S.C. Chapter 32 General § 21.5020 Post-Vietnam era veterans' educational...

  16. 77 FR 39613 - Presidential Determination on a U.S. Export Import Bank Transaction with Vietnam

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ...--Presidential Determination on a U.S. Export-Import Bank Transaction With Vietnam #0; #0; #0; Presidential... Presidential Determination on a U.S. Export Import Bank Transaction with Vietnam Memorandum for the Secretary... States to extend a loan in the amount of approximately $125,870,890 to the Vietnam Post...

  17. 38 CFR 21.5020 - Post-Vietnam era veterans' educational assistance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2014-07-01 2014-07-01 false Post-Vietnam era veterans... AFFAIRS (CONTINUED) VOCATIONAL REHABILITATION AND EDUCATION Post-Vietnam Era Veterans' Educational Assistance Under 38 U.S.C. Chapter 32 General § 21.5020 Post-Vietnam era veterans' educational...

  18. 3 CFR - Presidential Determination on a U.S. Export-Import Bank Transaction With Vietnam

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Bank Transaction With Vietnam Presidential Documents Other Presidential Documents Presidential... With Vietnam Memorandum for the Secretary of State Pursuant to section 2(b)(2)(D) of the Export-Import...,890 to the Vietnam Post and Telecommunications Group, a wholly state-owned company, for the...

  19. 76 FR 16384 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Initiation of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-23

    ... International Trade Administration Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam... antidumping duty order on certain frozen warmwater shrimp (``shrimp'') from the Socialist Republic of Vietnam (``Vietnam''), received on February 28, 2011, meets the statutory and regulatory requirements for...

  20. 38 CFR 21.5020 - Post-Vietnam era veterans' educational assistance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2011-07-01 2011-07-01 false Post-Vietnam era veterans... AFFAIRS (CONTINUED) VOCATIONAL REHABILITATION AND EDUCATION Post-Vietnam Era Veterans' Educational Assistance Under 38 U.S.C. Chapter 32 General § 21.5020 Post-Vietnam era veterans' educational...