HARVEST: High-mountain Asia - building Resilience to water Variability using Experiments, Surveys and accounts of Tradition. The glaciers and snowfields of the Himalayan mountain range provide meltwater that is critical for the many millions of people living in downstream areas, in Pakistan, India, Nepal and Bhutan for example. Their predominantly subsistence, agriculturally-based economies are entirely dependent on this supply of water during the dry (winter) season. These natural reservoirs are receding in the face of a warming climate, threatening food security in years to come. It is critical that vulnerable communities start to plan now for future water shortages, and develop simple but effective methods for harvesting and storing water during the rainy season, for use when the river discharge is low.  At the present time, how the contribution of meltwater to river flows varies through space and time is poorly quantified. We need to know this to be able to identify those communities that will experience the greatest reductions in water supply in the future. We also know relatively little about the communities that depend most on this resource - those in the mountains, generally marginalised from wider society and the national economy. We need to better understand their needs so that we can work with them to develop adaptation solutions. Our understanding of the history behind their current methods for irrigation and water capture and the politics and arrangements that determine their access to water is also very superficial. This needs to be better defined so that we can respect community heritage and offer adaptation solutions that are successfully integrated into current practices and are, ultimately, sustainable.  HARVEST will explore the methods with which we can close these knowledge gaps. Our team comprises scientists, social scientists, an environmental historian, an engineer, and an expert in public health. Critically, we are working with Practical Action, a leading international NGO based in Kathmandu, with expertise in grassroots development and poverty alleviation.  The scientists will take river water samples at different times of the year and at different locations, and use the concentration of stable isotopes (i.e. chemical signatures) to determine how much of the flow comprises snow and ice melt. This will provide quantitative data to identify those communities that will experience the greatest future water shortages. The social scientists will design and implement a household survey that will explore current issues of water use in the mountains, as well as irrigation and water harvesting/storage methods. The environmental historian will explore the British and Nepali archives for information on water use in Nepal, and establish the political and social contexts on which current access arrangements operate. Our engineer will work with the health scientist and Practical Action to identify adaptation measures that have been used in the past in rural mountain communities, and establish mechanisms by which the findings of the research team can be best used within these communities. Rather than offering particular solutions at this stage, the HARVEST team will have gathered experience and knowledge that will form the foundation of a broader-scale project across the Himalaya in a future funding call. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.