Fresh water resources in coastal areas are under intense pressure from groundwater consuming activities, sea level rise and extreme weather events, which effectively amplify salt water intrusion (SWI) into coastal freshwater aquifers. Literature on SWI describe the effects of SWI, model SWI scenarios and explain possible SWI mitigation strategies. To our knowledge there are, however, no studies that combine socioeconomic data with groundwater simulations to estimate SWI mitigation prevalence within an area. In this study, we demonstrate how a socioeconomic model can be combined with groundwater simulations to explore the possible role of behaviour willingness in finding suitable SWI adaptation/ mitigation strategies. The coastal province of Tra Vinh, located in the populated Vietnamese Mekong Delta, is an area affected by SWI and was used as case study area. Data collected from 313 households spread over nine communes, within the province, was used to construct a Bayesian Belief Network (BBN) model. The model integrates both socioeconomic (e.g. education, age) and psychosocial (behavioural) characteristics, to predict the willingness to change of the population; willingness to change from groundwater to a different source of water. The validated BBN model showed good model performances. The research found amongst others, using three model analysis, how the BBN model could be used on both regional (province) and local (commune) scale. The two different scales can help in defining both target groups and suitable locations for SWI mitigation/ adaptation interventions. Moreover, this study did not focus on finding suitable alternative water sources, that can serve as a substitute for groundwater abstraction. Though, the model analysis can help to more effectively define the possibilities of alternative sources and/ or water-saving interventions.