Peruvian Glacier Retreat and its Impact on Water Security (Peru GROWS) Meltwater from glaciers in the Peruvian Andes provides an important and reliable water supply for local and downstream communities for domestic purposes, hydropower, subsistence and commercial agriculture, and industry; and to support rare, high-elevation wetlands and wider ecosystem functioning. However, this long-term, reliable water supply is threatened by increasing temperatures and changing precipitation patterns in the mountainous areas, resulting in shrinking of glaciers and changes in the amount and seasonality of meltwater runoff. A warming climate is also associated with an increasing frequency of extreme hydrological events, such as floods and droughts. Coupled with the stresses of Peru's rapid urbanisation and economic development, these changes are expected to lead to significant water scarcity, with the potential to inhibit economic growth and degrade vulnerable ecosystems (and the services they provide), which in turn will increase social vulnerability, adversely affect the equitable sharing of resources, increase social conflicts, and destabilise Peruvian societies (from local communities to the large coastal urban centres).  Peru GROWS aims to increase the resilience of Peruvian communities and ecosystems to hydrological changes arising from shrinking glaciers in the Andes. Working in the Rio Santa catchment - the most glacierised catchment of Peru - we will map the current socio-ecological system to identify where, and how, different communities and ecosystems are exposed to risks from water availability. We will then integrate field measurements and remote-sensing data into physically-based glacier and hydrological models, to simulate the past, present, and possible future changes (to the end of the twenty-first century) to the climate, the glaciers, and to river flows (including amounts, seasonality, and inter-annual variability).  In close partnership with local stakeholders, we will exploit this new knowledge to explore the direct and indirect impacts of projected change in glacier behaviour on different communities in the catchment, with a focus on food security, aquatic and terrestrial ecosystems, and energy production. We will provide information on the current state of the water balance and hotspots of potential water scarcity/trade-offs that can be easily understood by key stakeholders and will provide the basis for adaptation planning at local and regional level.   Key stakeholders and end-users have been closely involved in the design of Peru GROWS and will co-deliver the research. Two key NGOs, with a long history of work in this region (CARE and the Mountain Institute) as well as social scientists at the National Glacier and Mountainous Ecosystems Research Institute and the Pontifical Catholic University of Peru, will act as an interface with  the local stakeholders, especially vulnerable rural communities. Together, they will have a key role in co-designing appropriate adaptation strategies for water resources management and agriculture that will create lasting positive impact. With this, we lay a firm foundation from which multiple impacts can emerge during and after the project. The Newton Fund builds research and innovation partnerships with developing countries across the world to promote the economic development and social welfare of the partner countries.