Vietnamese Mekong River Delta Research Articles

An investigation of timber frame housing in Vietnamese Mekong River Delta

Timber frame housing is one of the most common structures in many countries in the world. In Vietnam, timber frame buildings are well-known for having special whittling techniques that should be considered a lesson for modern methods. In the Vietnamese Mekong River Delta, the housing in rural areas was built mostly with timber frames, and some housing was built with bamboo frames and used natural materials such as nipa-leave, and coconut-leave. Therefore, the study aims to investigate the characteristics of timber frame housing in the Mekong River Delta. To achieve this, firstly, an on-site investigation of ten local housings in the Vietnamese Mekong River Delta is carried out. Secondly, the architectural characteristics of local housing are introduced, and finally, we analyze the details of timber frames. The result shows that the timber frame housing in the Vietnamese Mekong River Delta has the following features: simple structure, light framing, and a flexible connection to other local materials. These characteristics should be considered in detail as a lesson for housing design in the region.

Quantifying Spatio-Temporal River Morphological Change and Its Consequences in the Vietnamese Mekong River Delta Using Remote Sensing and Geographical Information System Techniques

The evolution of delta and riverbank erosion within the river basin can significantly impact the environment, ecosystems, and lives of those residing along rivers. The Vietnamese Mekong Delta (VMD), counted among the world’s largest deltas, has undergone significant morphological alterations via natural processes and human activities. This research aims to examine these morphological alterations and their impacts on local economic and social conditions in the VMD. This study utilized satellite data from 1988 to 2020, coupled with population density and land use/land cover (LULC) maps from 2002, 2008, and 2015. The findings reveal that the VMD experienced widespread erosion over the past three decades, covering an area of 66.8 km2 and affecting 48% of the riverbank length (682 km). In contrast to riverbanks, islets showed an accretion trend with an additional area of 13.3 km2, resulting in a decrease in river width over the years. Riverbank and islet erosion has had a profound impact on the LULC, population, and economy of the provinces along the VMD. From 2002 to 2020, eight different land use types were affected, with agricultural land being the most severely eroded, constituting over 86% of the total lost land area (3235.47 ha). The consequences of land loss due to erosion affected 31,273 people and resulted in substantial economic damages estimated at VND 19,409.90 billion (USD 799.50 million) across nine provinces along the VMD. Notably, even though built-up land represented a relatively small portion of the affected area (6.58%), it accounted for the majority of the economic damage at 70.6% (USD 564.45 million). This study underscores the crucial role of satellite imagery and GIS in monitoring long-term morphological changes and assessing their primary impacts. Such analysis is essential for formulating effective plans and strategies for the sustainable management of river environments.

Saving the Vietnamese Mekong River Delta—People's attitudes, opinions and willingness to help

AbstractThe unique nature and environment of the Vietnamese Mekong Delta as well as its agricultural production and its traditional lifestyle are endangered by a rising sea level and increasing salinization of the ground and surface water. This paper aims at the assessment of Vietnamese people's information on and attitudes towards these problems as well as their respective convictions and beliefs. Imbedded in an online survey with 2000 completed interviews we also conducted a Contingent Valuation study with which we want to assess people's willingness to contribute personally and financially to saving the Mekong Delta as an indication of the benefits they would expect from such a project. We interviewed three different groups of respondents, one of which lives directly in the Mekong Delta, a second lives outside the Delta, but close to it, that is in Ho Chi Minh City, and the third group lives far away from the Delta in Hanoi. With these three subsamples of respondents we wanted to capture not only the use benefits but also the nonuse benefits accruing from such a project. In the course of the interviews, we found that the Mekong Delta is of great interest and importance to all interviewees, no matter in which part of Vietnam they live. They were mostly well informed on the problems there and had strong opinions on the causes of these problems as well as on suitable strategies to fight them. In our Contingent Valuation study, we assessed the willingness of people at the different study sites to contribute financially to a hypothetical project for the preservation of the Mekong Delta and the socio‐economic, attitudinal and psychological determinants of this willingness. Besides these empirical findings, we also obtained valuable insights regarding various methodological aspects of Contingent Valuation studies.

Improving Salt Leaching in a Simulated Saline Soil Column by Compost and Biochar in Vietnamese Mekong Delta

The problem of seawater intrusion in recent years has been serious in the coastal provinces of the Vietnamese Mekong River Delta. For rice cultivation in salt-affected areas, more effective techniques are required to remediate the saline soils for lowing salinity to secure rice growth and productivity. The objective of this study was to evaluate the potential reclamation of compost and biochar in laboratory experiment using a saline soil sample from the rice cropping system. Our hypothesis was that the addition of compost and biochar might improve the infiltration rate, resulted in more effectively salts removing from saline soil. The experiment was set up with compost and biochar at rates of 5 g kg-1, 10 g kg-1 and 20 g kg-1, respectively and 10 g kg-1 compost combined with 10 g kg-1 biochar. Soil chemical characteristics such as amount of Na+, K+, Ca2+, and Mg2+ cations removed from soil into eluent by leaching, soil availabe N, P after finishing leaching were analyzed. Results indicated that all compost and biochar amendments enhanced Na+ leaching process. This study proved that material amendment such as 20g kg-1 biochar and 10g kg-1 compost plus 10g kg-1 biochar could speed up water infiltration. Compost additions increase the available N and P content in the soil after leaching. Available N and P contents have not been improved in treatments supplemented with biochar.

Inland dry season saline intrusion in the Vietnamese Mekong River Delta is driving the identification and implementation of alternative crops to rice

Inland dry season saline intrusion in the Vietnamese Mekong River Delta is driving the identification and implementation of alternative crops to rice

The role of migration in enhancing resilience to climate change

AbstractMigration out of areas affected by climate change has long been considered a common adaptation strategy. More recent studies, however, claim that migration should not exclusively be seen as an escape from areas under threat, but that it can also be understood as a powerful strategy towards change and innovation in those areas. This article examines the relationship between environmental stress and migration in the Vietnamese Mekong River Delta, one of the global hotspots of climate change. Based on an extensive survey among households and interviews with key actors, our study shows that indeed environmental stress is an important factor—though not the only one—behind the development of migration corridors, particularly to Ho Chi Minh City. Low-income households are more likely to have experienced migration than high-income ones. Low-income households also account for the largest group of recipients of financial remittances, which are mainly spent on basic household needs and health care, and not on longer-term investments. Our research also shows the important role of non-financial remittances in supporting climate resilience among vulnerable (low-income) households. Actually, in the Mekong Delta case, the transfer of knowledge and skills proves to be more prominent than the sending of cash. Such skills are brought along by returning migrants, and then passed on to others, leading to a diversification of local economies so that these become more resilient to environmental degradation.

Ecosystem Service Modelling to Support Nature-Based Flood Water Management in the Vietnamese Mekong River Delta

Deltas are among the most productive and diverse global ecosystems. However, these regions are highly vulnerable to natural disasters and climate change. Nature-based solutions (Nbs) have been increasingly adopted in many deltas to improve their resilience. Among decision support tools, assessment of ecosystem services (ES) through spatially explicit modelling plays an important role in advocating for Nbs. This study explores the use of the Land Utilisation and Capability Indicator (LUCI) model, a high-resolution model originally developed in temperate hill country regions, to map changes in multiple ecosystem services (ES), along with their synergies and trade-offs, between 2010 and 2018 in the Vietnamese Mekong Delta (VMD). In so doing, this study contributes to the current knowledge in at least two aspects: high-resolution ES modelling in the VMD, and the combination of ES biophysical and economic values within the VMD to support Nbs implementation. To date, this is the highest resolution (5 by 5 m) ES modelling study ever conducted in the VMD, with ~1500 million elements generated per ES. In the process of trialling implementations of LUCI within the VMD’s unique environmental conditions and data contexts, we identify and suggest potential model enhancements to make the LUCI model more applicable to the VMD as well as other tropical deltaic regions. LUCI generated informative results in much of the VMD for the selected ES (flood mitigation, agriculture/aquaculture productivity, and climate regulation), but challenges arose around its application to a new agro-hydrological regime. To address these challenges, parameterising LUCI and reconceptualising some of the model’s mechanisms to specifically account for the productivity and flood mitigation capability of water-tolerant crops as well as flooding processes of deltaic regions will improve future ES modelling in tropical deltaic areas. The ES maps showed the spatial heterogeneity of ES across the VMD. Next, to at least somewhat account for the economic drivers which need to be considered alongside biophysical valuations for practical implementations of ES maps for nature-based solutions (Nbs) in the upstream VMD, economic values were assigned to different parcels using a benefit transfer approach. The spatially explicit ES economic value maps can inform the design of financing incentives for Nbs. The results and related work can be used to support the establishment of Nbs that ultimately contribute to the security of local farmers’ livelihoods and the sustainability of the VMD.

Assessing the Performance of Climate Smart Rice Production Systems in the Upper Part of the Vietnamese Mekong River Delta

Climate smart agriculture (CSA) has gained considerable attention in Vietnam due to its potential to increase food security and farming system resilience while decreasing greenhouse gas emissions. In recent years, several CSA practices have been introduced in rice production, the most important sub-sector of Vietnam’s agriculture. However, few studies have been done in Vietnam to produce comprehensive assessments of CSA performance in the rice sector. This research proposes a comprehensive approach to assess CSA practices through a new set of evaluation indicators. A case study in An Giang province of the Vietnamese Mekong River Delta was implemented to evaluate the performance of five CSA models versus that of the triple rice crop system (i.e., benchmarking model). Results show that rice-shrimp and rice-lotus rotations are most profitable, low-risk, and applicable at a larger scale. Given that the current study analyzed and calculated only a small number of indicators and types of CSA practices, further research is necessary to test all indicators and diversified types of CSA models.

Cost-Benefit Analysis of Mixing Gray and Green Infrastructures to Adapt to Sea Level Rise in the Vietnamese Mekong River Delta

This study evaluated inundation impacts and the economic damage resulting from sea level rise (SLR) in the Vietnamese Mekong River Delta (VMRD), and identified the effectiveness of mixing gray and green infrastructures using cost-benefit analysis. The results showed that the VMRD could potentially be heavily affected by SLR. Without the implementation of proper adaptations, more than 90% of this area could be below sea level and nearly 20 million people could be affected by inundation by the end of the 21st century. The total economic damage could reach more than 22,000 billion US$ (2010 real value) by 2100 with no discount rate. These threats may increase the pressure on the region to ensure well-being, equity, and progress towards achieving sustainable development goals. However, achieving these goals will require the implementation of adaptations for upgrading and restoring in the region. This study assessed the effectiveness of adaptations and demonstrated that mixing gray and green infrastructures could benefit coastal inhabitants at a cost of 12 to 19 billion US$.

Impacts of farmers' adaptation to drought and salinity intrusion on rice yield in Vietnam's Mekong Delta

PurposeThe Vietnamese Mekong River Delta (VMD) is one of the most affected deltas by climate change in the world. Several studies have investigated factors influencing farmers' climate change adaptation behaviors in the region; however, little is known about the effectiveness of such measures. This paper examines the determinants of adaptation strategies among VMD rice farmers and assesses the impacts of such practices on rice yield.Design/methodology/approachEndogenous switching regressions were employed using a survey data of 300 rice-producing households in An Giang and Tra Vinh provinces in 2016.FindingsThe results show that farmers receiving early disaster warnings are more likely to adopt adaptation measures to climate change. If nonadaptors had chosen to respond, their rice yield would have increased by 0.932 tons/ha/season.Research limitations/implicationsThe data sample is small and collected from two provinces in the VMD only; therefore, the results may be specific for the study sites. However, future research can adopt the proposed method for other regions.Originality/valueThe study estimates the production impacts of farmers' decisions on whether or not to adapt to extreme climate events. The proposed approach allows for capturing both observed and unobserved behaviors.

Sustainable and conventional intensification: how gendered livelihoods influence farming practice adoption in the Vietnamese Mekong River Delta

The Vietnamese Mekong River Delta emerged as a rice production giant in the 1990s. Currently, the Vietnamese government is attempting to reduce environmental impacts resulting from the triple annual rice crop regime. This article explores how gender influences farming practice adoption using household livelihood survey data from Tien Giang Province. Each farm is disaggregated into male-managed, female-managed, and jointly managed plots. The study uses correlation to explore how sustainable intensification (SI) and conventional intensification (CI) practices are applied in complementary packages, and then a binary logistic regression to determine if livelihood approaches within households influence adoption of farming practices. The study finds that CI practices are more than twice as popular as SI practices, and that CI and SI practices are adopted in pairs that complement each other. The research also shows that gendered plot management is directly associated with SI and CI practice adoption, including decreased fertilizer use (p < .0005) and increased pesticide use (p = .047) on male-managed plots; and decreased likelihood of using organic fertilizers or compost (p = .013) or adopting integrated pest management (p = .004) on female-managed plots. Across all SI and CI practices, there is a significant indirect gendered impact due to unequal access between the sexes to natural and human capitals that are associated with increased SI adoption, such as education and extension trainings. This research contributes empirical evidence toward understanding the tension between CI and SI practice adoption and uniquely explores the gendered implications of the recent SI push in Vietnamese agriculture.

Enrichment of Polyunsaturated fatty acids from catfish oil with immobilized Rhizopus oryzea lipase

Nowadays, Pangasius hypophthalmus fillet is one of the main marine products in Vietnamese Mekong River Delta with over three hundred thousand tons per year. One of the byproducts of this industry is fat, about one hundred thousand tons per year. That byproduct has been only used in animal foodstuff industry after oil extracting or it becomes waste. In order to increase the quality of Pangasius hypophthalmus oil, we have enriched PUFA in the oil by hydrolysis with immobilized Rhizopus oryzea lipase. Lipase has been immobilized on celite by absorption method. Immobilization experiments have been designed in a two-level full factorial model with three factors. The fish oil has been hydrolyzed with immobilized lipase to enrich PUFA with optimized parameters found out: the ratio&#x0D; of enzyme to support of 1:10 g/g, the ratio of phosphate buffer volume to support weight of 30.55 ml/g, incubation time of 5.15 hours. The result has showed that 60-minute hydrolysis is the most appropriate. Additionally, the oil iodine value has increased from 71.4 to 97.4, and DHA concentration has risen from 1156mg/kg to 1916mg/kg.

Identifying Alternative Wetting and Drying (AWD) Adoption in the Vietnamese Mekong River Delta: A Change Detection Approach

Alternative wetting and drying (AWD) is an increasingly popular water-saving practice in rice production in the Vietnamese Mekong River Delta, especially considering the impact of projected climate change and reduced water availability. Unfortunately, it is very difficult to determine adoption without deploying thousands of costly household surveys. This research used European Space Agency Sentinel-1a and 1b radar data, combined with in-situ moisture readings, to determine AWD adoption through change detection of a time series wetness index (WI). By using a beta coefficient of the radar data, the WI avoided the pitfalls of cloud cover, surface roughness, and vegetative interference that arise from the sigma coefficient data. The analysis illustrated an AWD adoption likelihood scale across the delta and it showed potential for the use of remotely sensed data to detect adoption. Trends across the Vietnamese delta showed higher adoption rates inland, with lower adoption of AWD in the coastal provinces. These results were supported by a simultaneous effort to collect household level adoption data as part of the same project. However, correlation between the WI values and in situ soil moisture meter readings were most accurate in alluvial soils, illustrating a particularly strong relationship between soil type and WI model robustness. The research suggests that future change detection efforts should focus on retrieving a multi-season dataset and employing a power density analysis on the time series data to fully understand the periodicity of dry down patterns.

Energy development in Vietnam's Mekong river delta: a 'green' or 'grey' outlook?

The Vietnamese Mekong river delta (MD) is recognised as the biggest agriculture and aquaculture region of Vietnam. The MD plays an important role in ensuring food security for the country. The MD also has many sensitive ecosystems reliant on the ecology of the Mekong river basin. However, during the last decade, many electricity generation plants, both renewable and non-renewable power projects, have been built and some will be built in the near future in the MD. These energy plants' construction and operation may prove to be a challenge to the national energy strategy. This paper is a monograph review of two sides of energy sector industrialisation in the MD with a focus on 'green' and 'grey' socio-economic development (as 'xanh' and 'xam' in Vietnamese respectively). 'Green' energy is understood as the electricity generated from inexhaustible sources and known as renewable energy. It emits fewer greenhouse gases and causes less harm to habitats in comparison to traditional fossil fuels and hydropower. 'Grey' energy is another word for non-renewable energy or polluting energy, which can have negative effects on human health, environment, and climate. This paper finds that the MD's energy development plans at present might not be as 'green' as expected, due to more 'grey' power plans in the planning pipeline. This paper also considers an outlook on energy prices and impacts on long-term sustainable development of the MD.

Managing flood risks in the Mekong Delta: How to address emerging challenges under climate change and socioeconomic developments

Climate change and accelerating socioeconomic developments increasingly challenge flood-risk management in the Vietnamese Mekong River Delta—a typical large, economically dynamic and highly vulnerable delta. This study identifies and addresses the emerging challenges for flood-risk management. Furthermore, we identify and analyse response solutions, focusing on meaningful configurations of the individual solutions and how they can be tailored to specific challenges using expert surveys, content analysis techniques and statistical inferences. Our findings show that the challenges for flood-risk management are diverse, but critical challenges predominantly arise from the current governance and institutional settings. The top-three challenges include weak collaboration, conflicting management objectives and low responsiveness to new issues. We identified 114 reported solutions and developed six flood management strategies that are tailored to specific challenges. We conclude that the current technology-centric flood management approach is insufficient given the rapid socioecological changes. This approach therefore should be adapted towards a more balanced management configuration where technical and infrastructural measures are combined with institutional and governance resolutions. Insights from this study contribute to the emerging repertoire of contemporary flood management solutions, especially through their configurations and tailoring to specific challenges.

Integrating indigenous knowledge for participatory land use planning (PLUP) in Tra Hat hamlet, a climate-smart village in the Mekong River Delta, Vietnam

Agriculture is a primary source of livelihood in the Vietnamese Mekong River Delta with different land use activities. There are different potential conflicts in agricultural land use, including: water resources use and interests. Therefore, establishing feasible land use planning (LUP) in an area needs an in-depth participation and discussion among stakeholders (including: governments at different levels, local farmers, and national and international scientists). Indigenous knowledge of local farmers plays an important role in making land use decision, which can support solving land-use conflicts to achieve the most sustainable management of land resources. In this study, we integrated local knowledge into a land use planning process to assess the suitability of land use types and to project potential impacts of climate change conditions on land use decisions in the Tra Hat hamlet, one of the climate-smart village (CSV) sites in the Vietnamese Mekong River Delta. A total of two consultation meetings, using simple tools (resources mapping, timeline, seasonal calendar, wealth ranking, Venn diagram, pair wise ranking, and key informants’ interviews), were conducted, and 130 households were interviewed during a field visit in 2015. As a result, a participatory land use planning (PLUP) was implemented with active participation of the concerned communities to establish a suitable land use planning and identify the potential adaptation techniques in the near future (2020). Land use planning at the hamlet was discussed to get the agreement and the coordination among local governments, farmers and scientists on adaptation practices.

Mapping rice paddy extent and intensification in the Vietnamese Mekong River Delta with dense time stacks of Landsat data

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. Vietnam, one of the largest exporters of rice globally, grows most of its rice in the Mekong River Delta, but this low-lying and heavily populated area is susceptible to major land cover changes. To properly monitor and manage rice crops in this region, remote sensing with satellite imagery has been particularly useful; however, most efforts to map regional paddy area utilize coarse resolution MODIS or AVHRR data due to their high temporal frequency. Because the average size of a rice paddy field in the region is smaller than a coarse resolution pixel, we map the Mekong study area using finer-scale Landsat data collected across multiple growing seasons. First, we exploit dense Landsat time stacks for circa 2000 and circa 2010 to map rice paddy extent using vegetation trajectories, then combine these pixel-based rice maps with image-based segments to generate a polygon-based rice map. The results show that this method can map rice paddies with over 90% overall accuracy (and errors of omission and commission ranging from 6 to 25%) at a finer spatial resolution than previous efforts. Next, we differentiate between single-, double-, and triple-cropped rice paddies in the delta using a supervised classification based on exemplars of these different cropping trends. From circa 2000 to circa 2010, we find that triple-cropped rice fields have nearly doubled in area from one-third to nearly two-thirds of paddy area. Our work also highlights the importance of scenes that capture flooded fields, and the utility of cloud-covered scenes within the dense time stacks of data, to achieve higher classification accuracies. Methods to map rice paddies are vital to understanding the sustainability of these agricultural systems, and the work presented here makes strides toward routine monitoring at a field-level resolution.

Using a Risk Cost-Benefit Analysis for a Sea Dike to Adapt to the Sea Level in the Vietnamese Mekong River Delta

The purpose of this study is to conduct an economic valuation of creating a concrete sea dike system as an adaptation measure to counter the impacts of a rise in sea level using a risk cost-benefit analysis framework. It uses an ex-ante approach with risk considerations for storms, floods, and salinity by specifying probability distribution functions in a simulation process, in order to incorporate these risk factors into the analysis. The results showed that the benefits of storms and floods avoided dominated the dike options. The benefit of salinity avoided was also valuable, with annual rice and aquaculture productivity losses avoided of USD 331.25 per ha and USD 915 per ha, respectively. This study evaluated a range of dike options to adapt to climate change in the Vietnamese Mekong Delta, showing high levels of benefits compared to costs. The larger in scale the dike system options were, the higher the expected net present values (ENPVs) were. Of the dike alternatives applicable to the Vietnamese Mekong Delta, considering the impacts of sea level rise of storms, floods and raised salinity in soil from flooding, small scale dikes that can subsequently be increased in height should be a priority choice. The sensitivity analyses showed that the ENPVs of dike options were very sensitive with changes in discount rate but were not sensitive with increases in salinized areas at all. The findings provide evidence to support the necessity of the construction of a concrete sea dike system in the Vietnamese Mekong Delta, given the context of global climate change.

Measuring Household Resilience to Floods: a Case Study in the Vietnamese Mekong River Delta

The flood is a well-known phenomenon in the Vietnamese Mekong River Delta (MRD). Although people have experienced the impact of floods for years, some adapt well, but others are vulnerable to Resilience to floods is a useful concept to study the capacity of rural households to cope with, adapt to, and benefit from Knowledge of the resilience of households to floods can help disaster risk managers to design policies for with Most researchers attempt to define the concept of resilience; very little research operationalizes it in the real context of living with floods. We employ a subjective well-being approach to measure households' resilience to Items that related to households' capacity to cope with, adapt to, and benefit from floods were developed using both a five-point Likert scale and dichotomous responses. A factor analysis using a standardized form of data was employed to identify underlying factors that explain different properties of households' resilience to Three properties of households' resilience to floods were found: (1) households' confidence in securing food, income, health, and evacuation during floods and recovery after floods; (2) households' confidence in securing their homes not being affected by a large flood event such as the 2000 flood; (3) households' interests in learning and practicing new flood-based farming practices that are fully adapted to floods for improving household income during the flood season. The findings assist in designing adaptive measures to cope with future flooding in the MRD.

The palaeoenvironmental development of the northeastern Vietnamese Mekong River Delta since the mid Holocene

Three radiocarbon-dated sediment cores from the northeastern Vietnamese Mekong River Delta have been analysed with a multiproxy approach (grain size, pollen and spores, macro-charcoal, carbon content) to unravel the palaeoenvironmental history of the region since the mid Holocene. During the mid-Holocene sea-level highstand a diverse, zoned and widespread mangrove belt (dominated by Rhizophora) covered the extended tidal flats. The subsequent regression and coeval delta progradation led to the rapid development of a back-mangrove community dominated by Ceriops and Bruguiera but also represented locally by e.g. Kandelia, Excoecaria and Phoenix. Along rivers this community seems to have endured even when the adjoining floodplain had already shifted to freshwater vegetation. Generally this freshwater vegetation has a strong swamp signature but locally Arecaceae, Fabaceae, Moraceae/ Urticaceae and Myrsinaceae are important and mirror the geomorphological diversity of the delta plain. The macro-charcoal record implies that natural burning of vegetation occurred throughout the records, however, the occurrence of the highest amounts of macro-charcoal particles is linked with modern human activity.