The Ganges Delta in Bangladesh, a transboundary rural river basin, is an example of water-related calamities due to natural and human-induced stresses. It is an agriculture-dominated area with the presence of Sundarbans mangrove forest. Recently this area is facing unfavorable conditions due to limitations in quantity, quality, and timing of available freshwater. As a result, floods, droughts, water scarcity, stream depletion, salinity intrusion, excessive sedimentation are becoming common phenomena. These calamities are making this area unsuitable for agriculture and vulnerable to the Sundarbans’ ecosystem. This study aims to provide technical insight into issues related to water scarcity and projected agricultural water demand for 2020-2100 considering the climate change uncertainties. We addressed three critical areas to attain this purpose. As a first task, this study attempted to analyze and understand the observed hydrological changes over the past six decades to fathom the critical reasons for freshwater scarcity. Secondly, interdependency, availability, and accessibility of surface water and groundwater were analyzed to investigate the adequacy of current water demand and supply in agriculture, industrial and domestic sectors. Irrigation demand is much higher than others and occupies 93% of the total water demand. Similarly, irrigation is 96% of total water withdrawal. This high demand in the agriculture sector led to our next objective to estimate agricultural demand for this century. It helps to understand an overall agricultural water consumption scenario for the future. This study provides necessary background information, which is vital for hydro-economically feasible agricultural water management plans.