The receding of glaciers as a consequence of global warming is predicted to severely impact human life. Rapid reduction in the glacial area of the third pole, Himalayan was reported and a relative reduction of -39% to -68% and –44% to –67% for Mekong and Salween basin is predicted by 2050, respectively. It is well agreed that arsenic contamination in Southeast Asia is featured by contaminated sediments naturally eroded from Himalayan. The mechanism governing the concentrations and the release of arsenic to pore water along the Mekong and Salween river sub-region groundwater remain unknown. Given the trans-boundary nature of both Mekong and the Salween Basin further limited access to arsenic concentration and its data collection. Therefore, data collection on arsenic concentration along the Salween and Mekong River sub-region groundwater and the estimation on arsenic mass balance in groundwater can act as a support for climate mitigation plans. In this study, sample collection will be conducted along the Mekong and Salween river, sub-region groundwater, sub-region soils, and sediment. Data collected will be run with several modelling tools to predicts arsenic mobility. It is expected that the mass balance of arsenic in the aquifers will be affected by the shift in the monsoon trend and increase in discharge due to climate change.