6.4.1. Contributions regarding the multidisciplinary methodology
My study used a multidisciplinary methodology to assess the impacts of agricultural land- use dynamics and adaptation measures across spatial and temporal scales, considering three assessment dimensions: hydro-environmental, social and economic. Integration of different approaches helped to answer the research questions, representing a procedure typical of research addressing complex social problems and assessing multiple impacts of a natural phenomenon while exploring adaptation measures. The findings from my study should therefore help others tackle similar issues in the future, while also helping Vietnam choose priority actions on the issues examined.
This study builds on and expands the scientific literature concerning floodwater management on delta floodplains. The study advances the debate on whether existing strategies, often featuring development of hard infrastructure for land and floodwater management, are sustainable for a delta as a whole. In view of the repercussions of the extensive dike construction scenario associated with agricultural intensification, new strategies are clearly needed, offering sustainable adaptation measures for the delta system. Chapters 2 through 5 demonstrated many negative impacts of the existing land and floodwater management strategy, from the local to the delta level. A recommended alternative is more flood-friendly farming systems with low-dike protection where needed, to exploit the benefits of floodwaters and retain floodwaters on the delta floodplains. The methodology and conceptual framework used in the current study could be adapted for use on other deltas, such as in Bangladesh and Myanmar, as these face similar problems of agricultural intensification, especially on floodplains. With different cultures, socio- economic developments as well as physical conditions, the studies could be comparative based on the findings from the same methodology and conceptual framework applied. In addition, the conceptual framework, based on assessment of adaption measures considering the three dimensions of sustainability (hydro-environmental, social and economic) could be applied to assess adaptation measures in other fields. Clearly, this study in itself will thus contribute to comparative research in the future.
Application in the current research of the three-dimensional method across both spatial and temporal scales also constitutes a comprehensively referenced addition to this research tradition. Our application to the assessment over time and scale is yielding important insights. Over the temporal scale, the economic costs-benefits and environmental impacts of rice intensification were assessed since environmental degradation is a slow progressive process that affects cost benefits at farm level over time. This research on the assessment of different dike conversion periods has been instrumental in this regard. Over the spatial scale, water balance were assessed across scales to explain where the floodwater goes. This is also crucial to understand how the 1D-quasi2D modeling approach can return stable water flows in changing conditions by diverting water elsewhere. Cost and benefit were spatially evaluated from farm to delta scales, as local benefits may be off-set by external costs and impacts at the delta level. These are difficult to assess, but provide a scientific insight in delta-scale dynamics and perspectives, and my research indicates that these should be accounted for in delta policies.
The study contributes to the scientific knowledge base developed for the Mekong Delta Plan (2013). In that plan, Dutch experts proposed four scenarios for development of a safe, prosperous and sustainable delta. The overall strategy recommended is the use of no-regret measures and prioritization of short-term and long-term interventions for three delta regions: the Upper Delta, the Middle Delta and the Coastal Zone. However, the general
Chapter 6
121 measures recommended have not been expanded with, for example, case studies involving community perspectives. The research presented here explored adaptive measures for the Upper Delta, thus contributing case study-based knowledge to actions proposed within the Mekong Delta Plan. In particular, my findings provide a reference for the strategy, “coping with increased seasonal fluvial floods and enhancing the water retention capacity through adapted land and water use” recommended by Mekong Delta Plan for the upper floodplains. In the most promising scenario for a sustainable delta, so-called “agro-based industrialization” proposed by the Dutch experts, land-use policies are to be implemented that enhance seasonal flood-based agriculture within the floodplains. This is in line with my study’s findings.
6.4.2. Contributions regarding the conceptual framework
From a hydrodynamic perspective, this research contributes valuable knowledge on the hydrodynamic impacts of land-use changes associated with extensive construction of high dikes on the floodplains of a major delta. These impacts have been a topic of debate in recent decades. My findings shed light explicitly on where floodwaters go under the influence of land-use changes, based on water balance calculations. Furthermore, the limitations of 1D-quasi2D modeling in simulating floodwater dynamics were explored and a recommendation was made to develop a 2D or 3D hydrodynamic model for the delta. From a social perspective, my research helps people, especially decision makers and scientists, to better understand farmer perspectives on their livelihood systems and on various flood protection scenarios, both low dike and high dike. My research also explored alternative farming systems and assessed these based on the views expressed by farmers and experts, using a sustainable livelihood perspective. Additionally, the environmental implications of various farming systems were presented, alongside the impacts of these on farmers’ livelihoods in the long term.
From an economic perspective, the research showed that triple rice is not profitable over the long term and that it results in unsustainable livelihoods for rice farmers. Moreover, various scenario-based land-use development strategies were evaluated using cost-benefit analysis at the delta level. These economic evaluations will be useful for scientists and decision makers seeking strategies for sustainable development of the delta in the long term.