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It is feared that climate change could have dramatic effects on the socioeconomic and environmental settings in which human societies reside. It is projected that the Vietnamese Mekong Delta (VMD) will be among the most heavily impacted areas, as its coastal plains are considered to be highly vulnerable to both sea level rise and upstream discharge changes. This fluctuation in discharge could come about as a consequence of different changes further upstream, including shifting hydrological and land cover patterns, and socioeconomic development (especially hydropower development). In this chapter, the change in water resource patterns is presented to provide the general context of the situation in the VMD. Then the problems currently being experienced in the coastal plains are discussed, in order to illustrate changes in patterns of saline intrusion and its consequent impacts. Finally, water management strategies to sustain the development of the coastal plain in the context of climate change and upstream development are discussed.

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.

This chapter presents the application and comparison of three land-use planning (LUP) approaches in the coastal area of the Mekong Delta (MD), Vietnam. The land use of the studied area is diverse, quickly shifting and strongly contrasting. The contrast is not only in terms of resources but also in economic profitability and environmental sustainability. We wanted to use LUP approaches representing various levels of complexity and computation intensity, from empirical and qualitative to mechanistic and quantitative. From the variety of methods available, we selected a participatory LUP (PLUP) methodology, the guidelines for LUP by FAO enhanced with multi-criteria evaluation (FAO-MCE) and the land-use planning and analysis system (LUPAS) using interactive, multiple-goal linear programming. We used the same planning goal, worked in the same study area and the same period and produced three land-use plans. We compared the credibility, which is the technical and scientific appropriateness of the approach, and the stakeholder acceptability, which is the perception of the stakeholders of its practical value. The LUPAS map was best appreciated by stakeholders, but it also was the most expensive method. When comparing land-use plans of 2003 with actual land use of 2004, the PLUP map, which is disagreed with most strongly by the scientists, agrees best with the actual land use by the farmers. In the dynamic and contrasting land-use systems of the coastal MD, PLUP seems the most suitable approach for short-term advice, but for longer-term planning a combination of methods will probably work best.