Water and energy are two fundamental elements for achieving sustainable development in South Asia, a region facing many challenges of achieving the sustainable development goals under resource constraints. Water and energy are inherently inter‐dependent which requires a nexus perspective to address their synergy. However, sectoral approaches have been often used to deal with these twos interacting issues. It is therefore important to understand the quantitative linkage of water and energy and therefore find the opportunities by addressing the nexus at the planning stage for better resource management and utilization. This study aims to conduct an integrated assessment on water‐energy nexus which will be influenced by climate change up to 2050. An empirical study for the Ganges Basin have been conducted to develop and apply a methodology by linking different modelling techniques (hydrological modelling, energy scenario analysis and GIS spatial analysis) to address the practical conflicts between water and energy supply. This case study in Nepal provided relevant data on the projection of water availability and the projection on water demand in agriculture sector, industrial sector and domestic sector based on literature reivew for the river basin within the borders of Bangladesh. With the water availability projection to be conducted in Year 2 of this project, this study can be expected to deliver an assessment on the balance of water supply and demand and the scenarios on cross-border energy transmission.