The Vietnamese Mekong Delta (VMD) has experienced a series of unprecedented disasters in the last decade, resulting from a combination of drought and saline intrusion in the 2015-2016 and 2019-2020 dry seasons. These events have severely impacted the region's agricultural sustainability and people's livelihoods, prompting an urgent need to explore their root causes and derive lessons for future prevention. Despite a growing body of literature on disaster vulnerability, little has been done to address these questions in the Vietnamese context. This article seeks to bridge this gap by critically examining Vietnam's food politics and agricultural modernisation policies in relation to changes in water resource management, disaster risk management and farming practices. Through a case study of Tan Hung commune in Soc Trang province, the article argues that the current vulnerability to disasters, exemplified by the unsustainable system of triple rice cultivation, is an unintended consequence of Vietnam's agricultural reform and biased water management approach, which relies heavily on large-scale irrigation infrastructure.