Since Vietnam government adopted a comprehensive reform known as Doi Moi policy in 1986, agricultural sector, especially intensive rice production, has played a critical role in a substantial growth and contributed significantly to poverty reduction in the Mekong Delta. In promoting rice intensification and agricultural diversification, a series of high dyke systems and embankments have recently been installed in many inundation areas of the Mekong Delta to provide flood protection so that farmers could grow rice even during flooding seasons. Local government assumed that farmers in new flood-protected areas are able to diversify and intensify agriculture, particularly rice production, thereby improve local livelihoods. Innovations in artificial hydraulic management and changes in agricultural production, however, have not only generated a great impact on environment and ecology of the Mekong Delta, but also triggered a process of social differentiation, causing the appearance of marginalized groups who must struggle for access resources to maintain their survival. Studies on the aspects of social differentiation and local efforts to cope with such adverse impacts have been rare. This paper aims to investigate recent trends of human intervention to regulate floodwater flows for agricultural intensification in the Mekong Delta and to explore the diversity and dynamics of farmers in adapting with these changes by examining their livelihood strategies. The mixed method comprising participatory rural appraisal (PRA), field observations, in-depth interviews with key informants and household surveys was employed to collect necessary data. The analysis suggests that the local people’s livelihoods constitute dynamic, complex and diverse paths to respond to changing social, economic and environmental conditions after the appearance of the high dyke systems. Households and individual farmers differ in the degree of emphasis and choice of livelihood strategies, according to their own capacity in the broader socio-political and economic context and the structure of their internal size, composition and capital. However, the small-scale farmers and poor landless group have been seen at the losing end in the trade-off and thereby excluded from the development process.