Drivers of change and adaptation pathways of agricultural systems facing increased salinity intrusion in coastal areas of the Mekong and Red River deltas in Vietnam

Agricultural systems are increasingly considered complex adaptive systems. They are dependent on the integrated nature of biophysical and social sub-systems, continuously adapt to changing conditions and often display non-linear responses to various drivers of change at multiple scales. This research applied the lens of complex adaptive systems theory to analyze current and historical drivers of change and adaptation pathways of agricultural systems to increased salinity intrusion in coastal areas of the Red River and Mekong deltas in Vietnam since 1975. The analysis is based on 27 in-depth interviews with officials of local and national authorities as well as 198 semi-structured interviews and 11 focus group discussions conducted with farmers along three salinity transects in both deltas in 2015-2016. The results show that a dynamic interplay and feedback of various drivers of change such as policy intervention, farmers’ desire for profit maximization, changing salinity conditions, and technological development at different levels of the deltaic social-ecological system have shaped the changes and adaptations in agricultural systems over the last decades. In response to increased salinity intrusion, as exemplified by the historic salinity levels recorded in the Mekong Delta in 2015–2016, various adaptation options have been considered. These include adaptations that would lock-in agricultural production in particular systems or constrain changes in others, which is potentially problematic in light of the high uncertainty related to future changes. The study recognizes the need to apply both incremental and transformative changes and select adaptation pathways which allow for continuous change or that are reversible in order to avoid lock-ins and address future challenges. Additionally, attention should be drawn to interactions and feedbacks in future changes within and across adaptation pathways in order to prevent further increases in salinity intrusion and lock-in effects in agricultural systems within the deltas

Vulnerability and risk of deltaic social-ecological systems exposed to multiple hazards

Coastal river deltas are hotspots of global change impacts. Sustainable delta futures are increasingly threatened due to rising hazard exposure combined with high vulnerabilities of deltaic social-ecological systems. While the need for integrated multi-hazard approaches has been clearly articulated, studies on vulnerability and risk in deltas either focus on local case studies or single hazards and do not apply a social-ecological systems perspective. As a result, vulnerabilities and risks in areas with strong social and ecological coupling, such as coastal deltas, are not fully understood and the identification of risk reduction and adaptation strategies are often based on incomplete assumptions. To overcome these limitations, we propose an innovative modular indicator library-based approach for the assessment of multi-hazard risk of social-ecological systems across and within coastal deltas globally, and apply it to the Amazon, Ganges-Brahmaputra-Meghna (GBM), and Mekong deltas. Results show that multi-hazard risk is highest in the GBM delta and lowest in the Amazon delta. The analysis reveals major differences between social and environmental vulnerability across the three deltas, notably in the Mekong and the GBM deltas where environmental vulnerability is significantly higher than social vulnerability. Hotspots and drivers of risk vary spatially, thus calling for spatially targeted risk reduction and adaptation strategies within the deltas. Ecosystems have been identified as both an important element at risk as well as an entry point for risk reduction and adaptation strategies

Resilience of agricultural systems facing increased salinity intrusion in deltaic coastal areas of Vietnam

The resilience concept has provided a new insight and approach to the conventional perspective of agricultural management by emphasizing the need to maintain a diversity of future options to adapt to inevitable and often unpredictable changes. The concept has been taken up by various academic disciplines and development sectors, yet ways to define and operationalize resilience as a measurable concept are still being developed. We contributed to this ongoing effort by implementing a subjective resilience assessment method based on farmers’ perceptions of three resilience components: (1) the sensitivity of their agricultural systems to increased salinity intrusion, (2) the capacity to recover from salinity damage, and (3) the capacity to change to other systems if salinity increases in the future. We conducted 27 in-depth interviews with local and national authorities, 11 focus group discussions, and 118 semistructured and 219 structured interviews with farmers in case study villages located along salinity transects in the Mekong Delta and at different distances to sea dikes in the Red River Delta in Vietnam in 2015-2016. Results from the subjective resilience assessment reveal that none of the agricultural systems studied systematically scored higher than the other systems on all three resilience components, implying that an increase in one resilience component by switching agricultural systems would negatively affect others. Agricultural responses to this salinity problem will influence current and long-term adaptability of the systems to future changes in salinity intrusion and other social-ecological developments in the deltas. Improving resilience components, e.g., through policies and interventions, resource allocation, and farming system changes, to sustain agricultural production or facilitate transformation to alternative systems when necessary is critically important for agricultural systems facing stress. Complementing subjective resilience assessments with qualitative data is thus crucial for understanding the drivers of resilience to improve components of resilience for agricultural systems in the respective deltas

Occurrence and dissipation of the antibiotics sulfamethoxazole, sulfadiazine, trimethoprim, and enrofloxacin in the Mekong Delta, Vietnam

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 aquatic environment, yet the persistence of these antibiotics is of concern and might lead to chronic exposure of aquatic organisms as well as humans

Advancing ecosystems and disaster risk reduction in policy, planning, implementation, and management

No abstract available

Comparing index-based vulnerability assessments in the Mississippi Delta: Implications of contrasting theories, indicators, and aggregation methodologies

There are many index-based approaches for assessing vulnerability to socio-natural hazards with differences in underlying theory, indicator selection and aggregation methodology. Spatially explicit output scores depend on these characteristics and contrasting approaches can therefore lead to very different policy implications. These discrepancies call for more critical reflection on index design and utility, a discussion that has not kept pace with the impetus for vulnerability assessments and respective index creation and application following the Hyogo Framework for Action 2005–2015. Comparing index outputs is an effective approach in this regard. Here, the Social Vulnerability Index (SoVI®) and the vulnerability component of the Global Delta Risk Index (GDRI) are applied at census tract level in the Mississippi Delta and visually and quantitatively compared. While the SoVI® is grounded in the hazard/risk research paradigm with primarily socio-economic indicators and an inductive principal component methodology, the GDRI incorporates advancements from sustainability science with ecosystem-based indicators and a modular hierarchical design. Maps, class rank changes, and correlations are used to assess the convergence and divergence of these indexes across the delta. Results show that while very different theoretical frameworks influence scores through indicator selection, methodology of index calculation has an even greater effect on output. Within aggregative methodology, the treatment of inter-indicator correlation is decisive. Implications include the need for an increased focus on index methodology and validation of results, transparency, and critical reflection regarding assessment limitations, as our results imply that contradictory risk reduction policies could be considered depending on the assessment methodology used

Drought vulnerability and risk assessments: state of the art, persistent gaps, and research agenda

Reducing the social, environmental, and economic impacts of droughts and identifying pathways towards drought resilient societies remains a global priority. A common understanding of the drivers of drought risk and ways in which drought impacts materialize is crucial for improved assessments and for the identification and (spatial) planning of targeted drought risk reduction and adaptation options. Over the past two decades, we have witnessed an increase in drought risk assessments across spatial and temporal scales drawing on a multitude of conceptual foundations and methodological approaches. Recognizing the diversity of approaches in science and practice as well as the associated opportunities and challenges, we present the outcomes of a systematic literature review of the state of the art of people-centered drought vulnerability and risk conceptualization and assessments, and identify persisting gaps. Our analysis shows that, of the reviewed assessments, (i) more than 60% do not explicitly specify the type of drought hazard that is addressed, (ii) 42% do not provide a clear definition of drought risk, (iii) 62% apply static, index-based approaches, (iv) 57% of the indicator-based assessments do not specify their weighting methods, (v) only 11% conduct any form of validation, (vi) only ten percent develop future scenarios of drought risk, and (vii) only about 40% of the assessments establish a direct link to drought risk reduction or adaptation strategies, i.e. consider solutions. We discuss the challenges associated with these findings for both assessment and identification of drought risk reduction measures and identify research needs to inform future research and policy agendas in order to advance the understanding of drought risk and support pathways towards more drought resilient societies

Salinity-independent dissipation of antibiotics from flooded tropical soil: a microcosm study

River deltas are frequently facing salinity intrusion, thus challenging agricultural production in these areas. One adaption strategy to increasing salinity is shrimp production, which however, heavily relies on antibiotic usage. This study was performed to evaluate the effect of increasing salinity on the dissipation rates of antibiotics in tropical flooded soil systems. For this purpose, paddy top soil from a coastal Vietnamese delta was spiked with selected frequently used antibiotics (sulfadiazine, sulfamethazine, sulfamethoxazole, trimethoprim) and incubated with flood water of different salt concentrations (0, 10, 20 g L−1). Antibiotic concentrations were monitored in water and soil phases over a period of 112 days using liquid chromatography and tandem mass spectrometry. We found that sulfamethazine was the most persistent antibiotic in the flooded soil system (DT50 = 77 days), followed by sulfadiazine (DT50 = 53 days), trimethoprim (DT50 = 3 days) and sulfamethoxazole (DT50 = 1 days). With the exception of sulfamethoxazole, the apparent distribution coefficient increased significantly (p < 0.05) for all antibiotics in course of the incubation, which indicates an accumulation of antibiotics in soil. On a whole system basis, including soil and water into the assessment, there was no overall salinity effect on the dissipation rates of antibiotics, suggesting that common e-fate models remain valid under varying salinity

Population dynamics, delta vulnerability and environmental change: comparison of the Mekong, Ganges–Brahmaputra and Amazon delta regions

Tropical delta regions are at risk of multiple threats including relative sea level rise and human alterations, making them more and more vulnerable to extreme floods, storms, surges, salinity intrusion, and other hazards which could also increase in magnitude and frequency with a changing climate. Given the environmental vulnerability of tropical deltas, understanding the interlinkages between population dynamics and environmental change in these regions is crucial for ensuring efficient policy planning and progress toward social and ecological sustainability. Here, we provide an overview of population trends and dynamics in the Ganges–Brahmaputra, Mekong and Amazon deltas. Using multiple data sources, including census data and Demographic and Health Surveys, a discussion regarding the components of population change is undertaken in the context of environmental factors affecting the demographic landscape of the three delta regions. We find that the demographic trends in all cases are broadly reflective of national trends, although important differences exist within and across the study areas. Moreover, all three delta regions have been experiencing shifts in population structures resulting in aging populations, the latter being most rapid in the Mekong delta. The environmental impacts on the different components of population change are important, and more extensive research is required to effectively quantify the underlying relationships. The paper concludes by discussing selected policy implications in the context of sustainable development of delta regions and beyond

Making SDGs work for climate change hotspots

The impacts of climate change on people's livelihoods have been widely documented. It is expected that climate and environmental change will hamper poverty reduction, or even exacerbate poverty in some or all of its dimensions. Changes in the biophysical environment, such as droughts, flooding, water quantity and quality, and degrading ecosystems, are expected to affect opportunities for people to generate income. These changes, combined with a deficiency in coping strategies and innovation to adapt to particular climate change threats, are in turn likely to lead to increased economic and social vulnerability of households and communities, especially amongst the poorest