Scarcity of fresh water resources in the Ganges Delta of Bangladesh

•Drastic drop in Ganges flow at post-barrage era (1975–2015) intrudes salinity.•Increase of temperature, evapotranspiration and decrease of rainfall trends.•Recharge is highly variable, showing a decreasing trend, leading to uncertainty.•Unsustainable groundwater withdrawal compared with recharge.•Unsustainable freshwater conditions considering quality and quantitative aspects.