In the face of climatic and other socioeconomic changes, most South Asian countries having large and growing population, limited land resources, and increasing water stress face a common challenge of how to grow more food with the same or less land, less water, and increased energy prices. This concept paper seeks deeper understanding of the interlinkages among water, energy, and food, which is crucial to formulate cross-sectoral policies for more resilient and adaptable societies. In South Asia, such a nexus approach inevitably needs to take Himalayan ecosystem services into account. Rice and wheat, the staple foods in South Asia, require huge amounts of both water and energy. The Indus-Ganges-Brahmaputra plain - the sub-region's grain basket and one of the world's largest areas of irrigated agriculture - depends in large part on the Himalayan mountain system as a source of both surface and groundwater for irrigation; as a source of hydropower; and as a regulator of climate and a repository of agro-biodiversity. To sustain these services and to ensure both upstream and downstream food, water, and energy security in South Asia, policies and strategies must therefore promote improved management of Himalayan watersheds, forests, wetlands, and rangelands. Recommended measures include:

restoration of natural water storage capacity in the Himalayan watersheds through conservation of soil, ice, wetlands, permafrost, lakes, and aquifers
development of climate smart, environmentally and socially sound infrastructure to provide water for agriculture, hydropower generation, and downstream irrigation as well as to reduce runoff and flood risks to downstream areas
adequate investment for management of Himalayan watersheds, wetlands, and biodiversity
mechanisms for providing incentives to mountain communities for managing Himalayan ecosystems