He joined the International Rice Research Institute (IRRI) in the Philippines in 1997 to conduct research in GIS and water modeling for rice and shrimp production in the coastal area, crop modeling and socio-economic analysis for regional and national balancing of rice supply and demand, and developing optimization models for land use planning with many case studies in India, Malaysia, the Philippines, Thailand and Vietnam. In 2001, he was awarded a medal by the Ministry of Agriculture and Rural Development of Vietnam in recognition of his contributions to Agriculture and Rural Development.

From May 2003, he has served with the International Water Management Institute (IWMI) as a senior, then a principal researcher for water resources to study water modeling for managing conflicts between agriculture and aquaculture, analyzing climate change scenarios and companion modeling that combines role-playing games with agent-based models for facilitating integrated water resources management. He also  served as an international specialist for the Mekong River Commission (MRC) to analyze impacts of climate change on Mekong flow,  as theme leader for irrigation for the Mekong Program on Water Environment and Resilience (M-Power), and as research coordinator of SUMERNET. After his retirement in 2014, he returned to Vietnam and continued as an IWMI emeritus scientist. At present, he is a Science and Policy Advisor for LMPPI, SEI Affiliated Researcher, and Chair of the Steering Commitee of SUMERNET.