Evaluation of full-dike system impact on the flow regime in a flood prone area of the Mekong Delta.
The Mekong Delta is an important agricultural production region in Vietnam. The expansion of irrigated cultivated area has increased food production rapidly from 6.3 million tons in 1985 to 24 million tons in 2013, contributing more than 53% of food production of the country and over 90% of rice exports. Being a low-lying coastal region, the Mekong Delta is particularly susceptible to both riverine and tidal flooding, threatening not only agricultural production but also the safety of delta residents. The construction of flood protection "full-dikes" in the delta has progressed rapidly over the last twenty years, notably in flood-prone areas such as An Giang and Dong Thap Provinces, to protect inner paddy rice fields against flooding. However, adverse effects caused by a lack of floodwaters on the farmland and using triple rice cropping systems soon became apparent. They were not confined to protected areas: they also involved adjacent regions. This study updates and refines a quasi-2D hydraulic model for the entire Mekong Delta using MIKE 11 to simulate and evaluate water level changes during the flood season before and after full dike construction. Based on these results, recommendations for future dike development and flood risk management will be derived for the Vietnamese part of the Mekong Delta.