South Central Coast Of Vietnam Research Articles

Contamination Levels and Accumulation Profiles of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from South Central Coast of Vietnam

Contamination Levels and Accumulation Profiles of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from South Central Coast of Vietnam

Effects of groundwater evaporation on the natural recharge to groundwater lenses residing in coastal dunes in Southern Central Vietnam

Groundwater lenses in the coastal dunes along the South Central coast of Vietnam are often of shallow table. The lithologic composition of the vadose zone in these areas is mainly fine to medium-grained sand, characterised by high porosity. The vegetation is sparse, the annual time of sunrise is long, the air temperature and surface evaporation are high. The above-mentioned conditions are favourable for the evaporation of the groundwater. This study utilised direct evaporation measurement by Lysimeter (LS) according to the principle of water balance. The LS measurement is designed to simulate the groundwater level at a depth of 0.9 m to monitor groundwater loss due to evaporation corresponding to the conditions of natural climate and the vadose zones. Monitoring results showed that the total amount of groundwater evaporation in 2022 at three stations Da Nang, Phu Yen and Binh Thuan is 259.9, 335.6, and 377.0 mm, respectively. With the assumed groundwater level at a depth of 0.9 m, the annual amount of groundwater evaporation has caused the reduction in the groundwater level in the aquifer in Da Nang, Phu Yen and Binh Thuan by 0.64, 0.78, and 0.92 m, respectively.

Reinforcing the Effect of Warm Ocean Anomalies in the South China Sea on the Extended Tropical-Depression-Induced Heavy Rainfall Event in Hainan Island

An unusually persistent and heavy rainfall event occurred in Hainan Island from 1 to 9 October 2010, in association with one extended tropical depression (TD) over the South China Sea (SCS). Based on rain-gauge precipitation, satellite altimetry, in situ Argo profile, air–sea enthalpy flux, and reanalysis data, this study investigates the impact of warm ocean anomalies in the SCS on the formation and intensification of the extended TD, and their reinforcing effect on TD-related heavy rainfall. The TD intensified and migrated northward to the vicinity of Hainan Island. A thicker-than-normal warm subsurface layer that was present beneath the positive sea surface temperature (SST) anomalies contained a sufficient upper-ocean heat content to effectively restrain the TD’s self-induced SST cooling effect, and available enthalpy fluxes were therefore sufficient to support the maintenance of the TD. The composite analyses confirm the reinforcing effect of warm oceanic anomalies in the central SCS off the south-central coast of Vietnam on heavy rainfall in Hainan Island, with the composite precipitation of “Warm eddy” cases being significantly larger in Hainan Island and northern Vietnam than that of the “Normal” cases, using reanalysis and remote sensing precipitation data over 29 years (1993–2021).

Essential oil profiles of seeds, peels, and leaves obtained from Limnocitrus littoralis (Miq.) swingle species, in the Southcentral coast of Vietnam

The essential oils of seeds, peels, and leaves from Limnocitrus littoralis (Miq.) Swingle growing wildly on the southcentral coast of Vietnam were extracted by hydrodistillation method. The yields of the oils were recorded. The organoleptic and physicochemical properties of the oils were defined and evaluated according to international standards at 25 °C. A total of forty-three, fifty, and sixty-five components of these oils were analysed and identified, respectively. Major constituents in the seed oil were β-pinene (3.7%, Quang Ngai; 24.0%, Ninh Thuan), β-myrcene (11.1%, Quang Ngai; 59.2%, Ninh Thuan), o-cymene (57.7%, Quang Ngai), and limonene (18.5%, Quang Ngai; 94.5%, Phu Yen; 8.5%, Ninh Thuan). Major constituents in the peel oil included α-pinene (11.3%, Ninh Thuan), β-pinene (3.9%, Quang Ngai; 62.6%, Ninh Thuan), and limonene (54.0%, Quang Ngai; 94.0%, Phu Yen; 3.5%, Ninh Thuan). Major constituents in the leaf oils consisted of β-pinene (36.4%, Ninh Thuan), β-myrcene (38.0%, Quang Ngai; 28.9%, Ninh Thuan), and limonene (17.3%, Quang Ngai; 93.2%, Phu Yen). This research highlighted the aromatic value of bearing oil plants growing wildly on the Southcentral coast of Vietnam.

Application of HEC-HMS model and satellite precipitation products to restore runoff in Laigiang river basin in Vietnam

The Laigiang river basin in the South Central Coast of Vietnam plays an important role in the socio-economic development of Binhdinh Province. In recent decades, the region has experienced commonly flooding in vast areas. This research aims to simulate event-based rainfall-runoff modelling, a historical flood event in December 2016, by applying the HEC-HMS model and rainfall data from CHIRPS. The CHIRPS data is an acceptable potential data input of the hydrology model. These have been confirmed through reliable validation indexes: The peak flood flow rate of 2,542.6 m3/s corresponds to the flood frequency of 5%; NSE with the value at 0.95; R2 coefficient reached 0.87; PBIAS being around 0.45, and PFC being at 0.89. It shows better performance in the rainy season than in the dry season. Inclusive, the CHIRPS rainfall data set and the HEC model could be used for some operational purposes in weather forecasting, especially for flood warnings in river basins in the South Central Coast, Vietnam.

Fingerprinting and source apportionment of dioxin contamination of soils and chicken eggs in Southeast and Central Vietnam.

Free-range chicken eggs and topsoil samples from private households in Southeast and South Central Coast of Vietnam were investigated to identify potential PCDD/F sources using Positive Matrix Factorization (PMF) approach. The PMF-extracted egg congener patterns were transformed to soil patterns using bioaccumulation factors and then compared to extracted soil and known dioxin sources patterns described in the literature. Free-range chicken egg PCDD/F profiles allowed to more precisely identify and distinguish potential PCDD/F sources. Five main PCDD/F sources were identified: open burning, vehicle emissions, background atmospheric deposition, Agent Orange, and so-called OCDD dechlorination pattern. The latter is characteristic for natural formation or ultimate weathering under tropical conditions of any primary source with predominant OCDD. Agent Orange source contribution ranged from 48 to 96% in soils, from 9 to 94% in eggs in hotspots, and from 10 to 31% in soil and from 4 to 45% in eggs in sprayed areas, respectively. Contributions of other sources varied significantly between sites.

Integration of GIS and Markov chain model for land use change assessment: A case study in the upstream Ba river basin, Gia Lai province

Ba river is the biggest river system in the South-Central Coast of Vietnam and plays a significant role in the socio-economic development of the region. Recently, land-use changes in Gia Lai province have been significantly transformed. Hence, to provide the information for land-use planning, there is an urgent need for land-use change assessment in the upstream Ba river basin. This study employed the Markov chain coupled with GIS to assess land-use changes between 2010 - 2015 and 2015 - 2020 periods. The results showed that during the period 2010 - 2015, there was no significant conversion of agricultural and reserve forest land. Meanwhile, a large proportion of unused (86%) and water and aquacultural land (57.5%) was converted into the other land-use types. Between 2020 and 2015, unused land decreased while the surface water and aquacultural land increased. The forest land accounted for a significant area (51.16%) during the 2015 - 2020 period. In addition, the driving forces leading to these changes were also analyzed, providing a more comprehensive of land-use change in the study area. In general, GIS and Markov were suitable for assessing land-use change. This study outcomes provide a general framework for land-use planning in Gia Lai province.

Application of Remote Sensing Imagery and Algorithms in Google Earth Engine platform for Drought Assessment

In Vietnam, drought is one of the natural disasters caused by high temperatures and lack of precipitation, especially with El Nino and the global warming phenomenon. It affects directly environmental, economical, social issueproblems, and the lives of humans. Many methods have been used to assess drought, andin which remote sensing indices are considered the most commonly used tool today. They are used to analyze spatio-temporal distribution of drought conditions and identify drought severity. Especially with the launch of Google Earth Engine (GEE) - a cloud-based platform for geospatial analysis, it is easy to access high-performance computing resources for processing multi-temporal satellite data online. With the GEE platform, we focus on writing and running scripts with the indicators suitable for evaluating drought phenomenon, instead of calculating on software and downloading remote sensing imagery with large size. In this study, we collected 26 Landsat 8 images in the dry season in 2019 (from April to July) in Tay Hoa district, Phu Yen – a region in the South Central Coast of Vietnam where agricultural drought occurs frequently. wWe assessed the distribution of drought conditions in the dry season in 2019 in Tay Hoa district, Phu Yen – a region in the South Central Coast of Vietnam where agricultural drought occurs frequently by using a drought index (VHI index – Vegetation Health Index) produced from Landsat satellite data in the GEE platform. The study results indicated that the drought (from mild to severe) concentrated in the North of the region, corresponding to high surface temperature and NDVI low or NDVI moderate values. VHI maps were visually compared with the drought map of the South Central Coast and the Central Highlands. In general, the results also reflect the the method’s reliability and can be used to support the managers to plan policies, making long-term plans to cope with climate change in the future at Tay Hoa in particular and other regions in general.

Persistent Clones and Local Seed Recruitment Contribute to the Resilience of Enhalus acoroides Populations Under Disturbance

Human-induced land use in coastal areas is one of the main threats for seagrass meadows globally causing eutrophication and sedimentation. These environmental stressors induce sudden ecosystem shifts toward new alternative stable states defined by lower seagrass richness and abundance. Enhalus acoroides, a large-sized tropical seagrass species, appears to be more resistant toward environmental change compared to coexisting seagrass species. We hypothesize that reproductive strategy and the extent of seedling recruitment of E. acoroides are altered under disturbance and contribute to the persistence and resilience of E. acoroides meadows. In this research, we studied eight populations of E. acoroides in four lagoons along the South Central Coast of Vietnam using 11 polymorphic microsatellite loci. We classified land use in 6 classes based on Sentinel-2 L2A images and determined the effect of human-induced land use at different spatial scales on clonal richness and structure, fine-scale genetic structure and genetic diversity. No evidence of population size reductions due to disturbance was found, however, lagoons were strongly differentiated and may act as barriers to gene flow. The proportion and size of clones were significantly higher in populations of surrounding catchments with larger areas of agriculture, urbanization and aquaculture. We postulate that large resistant genets contribute to the resilience of E. acoroides meadows under high levels of disturbance. Although the importance of clonal growth increases with disturbance, sexual reproduction and the subsequent recruitment of seedlings remains an essential strategy for the persistence of populations of E. acoroides and should be prioritized in conservation measures to ensure broad-scale and long-term resilience toward future environmental change.

THE CREATION OF BIOCLIMATIC VEGETATION MAP TO DEVELOP SUSTAINABLE AGRO FORESTRY IN BA AND KONE RIVER BASIN, VIETNAM

Bioclimate and natural vegetation have a long - term relationship that identify the potential vegetation distribution at different areas. For that reason, bioclimatic classification system was applied to the territory of Ba and Kone river basin, Vietnam. The precipitation and temperature dataset of Ba and Kone river basin was collected from 17 climate, hydrology, rain gauge stations which allowed to create a bioclimatic map at a scale of 1:250.000. Three bioclimatic factors of thermal-moisture basic conditions such as annual temperature (TN), annual rainfall (RN), length of dry season (n) are selected as criteria system of Ba and Kone river basin’s bioclimate. In order to describe the relationships between bioclimatic variables and zonal vegetation units, the resulting map presented 12 bioclimatic units corresponding distribution of vegetation from low to high altitudes. By building bioclimatology map in Ba and Kone river basin, the government can develop sustainable agro forestry in Central Highlands and South Central Coast of Vietnam.

Key Factors Affecting Sustainable Tourism in the Region of South Central Coast of Vietnam

Sustainable tourism is the development of tourism activities to meet the current needs of tourists and indigenous peoples while paying attention to the conservation and improvement of resources for the development of tourism activities in the future (World Tourism Organization, 2013). With the aim of identifying factors affecting the development of sustainable tourism in the South Central Coast of Vietnam, the study conducted a typical survey of 160 tourism managers and 240 tourists traveling or have participated in tourism activities of 8 provinces in the South Central Coast of Vietnam, and used the exploratory factor analysis (EFA) analysis and regression analysis for analyzing the data. The research results show that 11 factors impact the development of sustainable tourism in the South Central Coast namely Institutions and policies for tourism development, Infrastructure, Tourism resources, Human resources for tourism, Diversity of tourism services, Relevant support services, Activities of association and cooperation for tourism development, Tourism promotion and encouragement, Tourists' satisfaction, Local community, and Other factors. At the same time, among the above factors, the factors Institutions and policies for tourism development, Infrastructure, Tourism resources, and Local community strongly impact the development of sustainable tourism in the region.

Morpho-anatomical characteristics and antimicrobial activity of crude extract of Tephrosia villosa (L.) Pers. growing on sandy soil of Phan Thiet City, Binh Thuan Province, Vietnam

Tephrosia villosa (L.) Pers. is an herb species distributed mainly in arid sandy lands of the South Central Coast of Vietnam, including Binh Thuan province. The existing Vietnamese folk remedies have mentioned the medicinal effects of this herb in the treatment of edema and diabetes. Documents available in Vietnam provided only basic information on the morphology of this species. Therefore, this study aimed to investigate the morphological and anatomical characteristics of stems, leaves and roots of the plants in the analysis of relation to climatic conditions of the region. Antibacterial activity was initially studied as a basis for subsequent pharmacological studies. The crude ethanolic extracts were tested for inhibitory against Pseudomonas aeruginosa and Staphylococcus aureus by agar well diffusion method. The results showed that the plants had formed the morpho-anatomical characteristics to adapt to strong wind, strong light, high temperature, and dry sandy soils of the region. The ability to inhibit the two mentioned bacteria via the diameters of the halo was 10.8 – 12.7 mm, respectively. The recommendation was to continue to study the anatomical characteristics of the primary roots to complete the data and further investigate the antibacterial and antifungal activities of extracts of Tephrosia villosa.

A Hybrid Approach Using GIS-Based Fuzzy AHP–TOPSIS Assessing Flood Hazards along the South-Central Coast of Vietnam

Flood hazards affect the local economy and the livelihood of residents along the South-Central Coast of Vietnam. Understanding the factors influencing floods’ occurrence potentially contributes to establish mitigation responses to the hazards. This paper deals with an empirical study on applying a combination of the fuzzy analytic hierarchy process (AHP), the fuzzy technique for order of preference by similarity to ideal solution (TOPSIS), and a geographic information system (GIS) to assess flood hazards along the South-Central Coast of Vietnam. Data are collected from focus group discussions (FGDs) with five communal authorities; a questionnaire completed by eight hamlet heads in the Phuoc Thang commune (Binh Dinh province); and documents, reports, and thematic maps provided from official sources. A total of 12 maps of flood factors are prepared. The results show that terrain elevation, creek-bottom terrains, high tide-induced flooding area, and distance to water body are the main factors affecting flood hazards. The An Loi hamlet faces the highest risk for floods, followed by Lac Dien, Luong Binh, and Pho Dong. The map of flood hazards indicates the western part is assessed as low hazard, whereas the eastern part is a very high hazard area. The study findings show that the hybrid approach using GIS-based fuzzy AHP–TOPSIS allows connecting decision makers with the influencing factors of flooding. To mitigate floods, both the Vietnam national government and the Binh Dinh provincial government should integrate natural hazard mitigation into socio-economic development policies.

Orchidantha anthracina (Lowiaceae), a new species from Vietnam

Orchidantha anthracina (Lowiaceae), discovered at the south central coast of Vietnam, is described and illustrated, bringing the total number of species in the family to 26, of which four occur in Vietnam. The notes on distribution, habitat and etymology are given and a preliminary conservation assessment is provided. The species is compared with O. vietnamica, with which it shares flowers of similar size and colours, but from which it is readily distinguished by a narrow and strongly reflexed dorsal sepal and spreading lateral sepals, not supporting the labellum. Notes with additional comparison to all species with a similar arrangement of lateral sepals are also provided.

Microbiome dataset analysis from a shrimp pond in Ninh Thuan, Vietnam using shotgun metagenomics.

Vietnam is one of the top shrimp producing and exporting countries in the world [1]. However, viral and bacterial epidemic diseases cause severe damages to shrimp farming, resulting in millions of US dollars losses annually [2]. Furthermore, inappropriate use of antibiotics in shrimp rearing lead to increased emergence of drug resistant pathogens [3]. Current practices for water quality control, mostly based on chemical and physical parameters; neglected biological criteria necessary for maintaining pond health.Ninh Thuan is a region situated in the South Central Coast of Vietnam. Due to its geographic location, a large part of this region is dedicated to shrimp (Litopenaeus vannamei) post-larvae production and rearing. This article presents a microbiome dataset from two water samples collected in a shrimp rearing pond in Ninh Thuan. We used Oxford Nanopore Technologies (ONT) for metagenomic sequencing of the samples to characterize microbial communities and antibiotic resistance profiles. The metagenome dataset generated will provide an understanding and comparison framework of the microbial diversity and functionality among shrimp ponds with potential application in health management and shrimp rearing industry.

Spatial patterns of health vulnerability to heatwaves in Vietnam.

The increasing frequency and intensity of heat events have weighty impacts on public health in Vietnam, but their effects vary across regions. In this study, we have applied a vulnerability assessment framework (VAF) to systematically assess the spatial pattern of health vulnerability to heatwaves in Vietnam. The VAF was computed as the function of three dimensions: exposure, sensitivity, and adaptive capacity, with the indicators for each dimension derived from the relevant literature, consultation with experts, and available data. An analytic hierarchy process (AHP) was used to determine the weight of indicators. Each province in Vietnam's vulnerability to the health impacts of heatwaves was evaluated by applying the vulnerability index, computed using 13 indicators (sensitivity index, 9; adaptive capacity index, 3; and exposure index, 1). As a result of this analysis, this study has identified heatwave vulnerability 'hotspots', primarily in the Southeast, Central Highlands, and South Central Coast of Vietnam. However, these hotspots are not necessarily the same as the area most vulnerable to climate change, because some areas that are more sensitive to heatwaves may have a higher capacity to adapt to them due to a host of factors including their population characteristics (e.g. rates of the elderly or children), socio-economic and geographical conditions, and the availability of air-conditioners. This kind of information, provided by the vulnerability index framework, allows policymakers to determine how to more efficiently allocate resources and devise appropriate interventions to minimise the impact of heatwaves with strategies tailored to each region of Vietnam.

Coral reef fishes in the banks and rocky islands in the offshore waters of Binh Thuan province

Binh Thuan province is located in the South Central Coast of Vietnam with favorable conditions for living coral reefs. The coral reefs were mainly investigated in coastal water areas and Phu Quy island, meanwhile other areas such as the banks and rocky islands seem to lack information. This study was conducted to evaluate the species composition and distribution of coral reef fish communities in the Royal Bishop banks and around rocky islands in Julia shoal in the offshore waters of Binh Thuan province in April 2019. A total of 151 species belonging to 86 genera and 33 families of coral reef fishes were recorded. Among them, 4 species for the first time recorded in Vietnam are Helcogramma striata (Hansen, 1986) (Tripterygiidae), Pseudanthias squamipinnis (Peters, 1855) (Serranidae), Bodianus bilunulatus (Lacepède, 1801) and Coris aygula (Lacepède, 1801) (Labridae). The total average density of coral reef fish in the offshore waters of Binh Thuan is quite high at 1,104.9 ± 617 individuals/250 m2, most of them are small sized fish and ornamental fish group, the large sized fish and target fish group accounts for a relatively low rate, but their density here is much higher compared to that in the coastal waters of Binh Thuan province. The comparative analysis also shows that sites in coral reef around rocky islands have species richness and density of coral reef fish higher than the bank area.

An Assessment of Sustainable Development in the South Central Coast of Vietnam during the Period from 2010 to 2016

In the context of global change, the rapidly increase of socio-economic development can trigger the negative impacts on coastal resources, environment and ecosystems, causing the deterioration of the system sustainability. Vietnam is one of the most vulnerable countries by climate change. Of which, the South Central Coast (SCC) is a highly vulnerable area to climate extreme events and sea level rise. This research aimed to build a theoretical framework for evaluating the level of sustainable development in the SCC. By using Delphi method, Interpolation method and Evaluation method, the research proposed a set of indicators, which consists of 32 indicators of the four dimensions (Economic; Social; Environmental; Infrastructure and Governance) in order to evaluate the sustainable development index (SDI) of the SCC provinces. Results show that the SDI had an increased tendency from 2010 to 2016. In general, Da Nang is the capital of the region and the SDI was highest which increased from 0.38 in 2010 to 0.61 in 2016 through the development of economic, infrastructure and urban governance dimensions. In contrast, during the survey, Binh Dinh and Phu Yen’s SDI were still lower than other provinces. Results suggested that it is necessary to enhance the policy and planning to implement the sustainable development goals together with the economy, society, environment and infrastructure development. The sustainable development indicators can potentially contribute to apply to monitor the sustainable development in other coastal regions in Vietnam.
 
 

Simulation of Storm Surges in the South Central Coast of Vietnam Under Climate Change

The research was supported by National Research Project Program of Vietnam: science and technology in response to climate change, natural resources and environmental management in the 2016-2020 period (program number: BĐKH/16-20), Developing a sustainable socio-economic model adapting to extreme natural disasters under climate change in the South Central region of Viet Nam. A case study of Ninh Thuan province (grant number: BĐKH.04/16-20). Abstract This paper presents the results of storm surge simulation in the South Central region of Vietnam using the Mike 21-FM HD model. Wind pressure fields of typical storms were first identified in period of 1986-2005 using the parametric wind field model. Storm surge risk was then simulated based on the rare 10, 50 and 100-year frequency corresponding to 2030, 2050, and 2100 scenarios. Storm surge model was finally calibrated and validated using the level of water measured in the November 2009 Typhoon Mirinae and October 2013 Typhoon Nari. The results show that storm surges were consistent with water level variation and amplitude; the maximum and minimum storm surges were 2.34m in the Binh Thuan coastal area and 0.78m in the Khanh Hoa coastal area, respectively. The results of this study demonstrated the use of MIKE 21-FM HD model for the simulation of storm surges in the future plays an important role in damage risk reduction caused by storm surges. Keywords: storm surge simulation, climate change, Mike 21-FM HD model, South Central coast of Vietnam. DOI : 10.7176/JEES/9-6-08 Publication date :June 30 th 2019

A survey on electrical appliance use and energy consumption in Vietnamese households: Case study of Tuy Hoa city

The domestic sector is responsible for approximately a third of total energy consumption in Vietnam. However, research on the details of energy consumption in this sector is relatively poor and there is a lack of data on actual energy use in households. This study attempts to fill the gap by providing an analysis of appliance penetration, usage behavior, and actual energy consumption of Vietnamese homes. Data were collected from a survey of 60 households in Tuy Hoa City on the South-Central Coast of Vietnam in 2017. The result shows that the average energy consumption was 4492 kWh per household per year, in which electricity and liquefied petroleum gas accounted for 74.4% and 25.6% respectively. The breakdown of current energy consumption revealed that cooling was the primary consuming end-use with 31.9% of the total, followed by cooking gas with 25.6% and kitchen appliances with 18.5%. Energy consumption for typical households with various ownership levels of air conditioner were also predicted. The results of this study are therefore a valuable reference for policy makers, energy planners and Vietnamese households themselves to understand the existing energy consumption characteristics and identify potential ways to improve energy efficiency in dwellings.