In the background of increasing global consciousness that scarcity of water will become a major obstacle to sustainable development in the next century, this paper analyses the future challenges in water resource planning and management in the Ganges-Brahmaputra basin in Asia. It analyses the problems of water scarcity and regular annual flooding in some parts of the basin with the help of its geomorphological and climatic peculiarities. The ecological sustainability and economic viability of big dams in the Himalaya are examined. The problems of undertaking joint projects on water resources between the upstream countries of Nepal and Bhutan and the downstream country of India are analysed. Similarly, the problem of the sharing of Ganges waters between India and Bangladesh is presented. The paper summarizes some main elements of the challenges to be faced in the immediate future in order that the densely populated river basin can keep open the options of sustainable development in the future.