Resilience and shifts in agro-ecosystems facing increasing sea-level rise and salinity intrusion in Ben Tre Province, Mekong Delta

Coastal areas of the Mekong Delta in Vietnam are increasingly experiencing salinity intrusion in freshwater systems, in part due to climate change induced sea-level rise, compromising agricultural production and domestic water supply. In order to determine which development trajectories could result in resilient agro-ecosystems, a study area in Thanh Phu district, Ben Tre province was selected where the influence of salinity intrusion on agro-ecosystem can be studied along spatial and temporal salinity gradients. The district is divided in three sub-regions: sub-region 3, closest to the coastline, is principally dedicated to brackish-water shrimp farming; more inland, sub-region 2 has a mix of rice-shrimp farming; and further inland, sub-region 1, which is protected from salinity intrusion by a system of dykes, is dedicated principally to rice farming. Household and expert interviews, focus group discussions and a review of policy documents were used to capture historical salinity problems as well as shifts in farming systems. Agricultural activities have changed in the last decades, mainly driven by national-level policies. At present, the development of engineered infrastructures is favoured whereas complementary or alternative solutions to increase the resilience of social-ecological systems with respect to salinity intrusion exist. These include regeneration of coastal ecosystems, agronomic measures, upstream flow control and shifts in agro-ecosystems. The latter would increasingly enable farmers to work under the influence of both saline and freshwater systems allowing income diversification. National authorities have an opportunity to change the business as usual mode of tackling water-related problems including extreme events in the Mekong Delta through infrastructure development by looking at these alternative solutions.