PEGASUS: Producing EnerGy and preventing hAzards from SUrface water Storage in Peru

The Peruvian Andes is home to 71% of the world's tropical glaciers, and the meltwater they supply is an essential resource for people downstream who depend on it for irrigation and sanitation. Further, hydropower plants driven by glacial meltwater provide more than 40% of Peru's electricity. However, Peru's glaciers are receding rapidly, threatening this supply, as well as releasing sediment to valley areas and revealing topographic depressions that may become natural reservoirs for glacier runoff. These thawing landscapes are also very active and can pose risks to downstream people and infrastructure. PEGASUS will assess the opportunities and threats that rapidly evolving landscapes, and natural resources, will bring to the people and businesses of three glacierised Cordilleras of the Peruvian Andes - Urubamba, Vilcabamba and Vilcanota - and make recommendations that will maximise the potential prosperity that can be gained in the face of continued environmental change.

Modelling the climate of mountain catchments such as those in Peru is complex because of the interaction of large-scale weather systems with local-scale winds and extreme relief. Uncertainties in modelling the climate feed into projections of glacier change, which themselves are limited by a lack of data on previous glacier behaviour for calibration, and downstream river flows for validation. Robust climate modelling is also required for predictions of permafrost (freezing) heights, which are a key control on ice and bedrock stability, and thus avalanche risk. PEGASUS will produce new and refined projections of climate that will drive cutting edge glacier and permafrost models, to yield firm predictions of how the glaciers and freezing levels will change on a 5-yearly interval from now until the end of the century.

As the glaciers recede and hillslopes become more active, sediment will be released into the valleys, and lakes will develop where ice existed. Some of the sediment will be trapped within these glacial lakes, and some will be transferred downstream by river flows. The rate of sediment release by glaciers in advanced states of recession is poorly known, and the role of lakes in capturing the sediment is also poorly quantified. PEGASUS will perform field measurements and modelling to improve understanding of the role of glacial lakes in removing, conveying and storing sediment being released from the glaciers, and characterise the impact this will have on downstream water quality and critical hydropower infrastructure.

The locations of future glacial lakes can be predicted by modelling the thickness of the current glaciers and identifying subglacial depressions that will be revealed as the ice recedes. Using a Digital Elevation Model (DEM) of this ice-free terrain, it is possible to make a quantitative assessment of the hazard that these new lakes, as well as existing glacial lakes, pose to downstream areas if they were to burst catastrophically. PEGASUS will carry out this assessment for the largest lakes in the Urubamba-Vicabamba-Vilcanota study area and then undertake additional fine-resolution and physically-based numerical modelling to robustly quantify the effects of flooding and debris flows on people, land, the downstream river dynamics, and hydropower infrastructure.

PEGASUS will then identify the barriers and opportunities that exist to the use of these lakes for water storage and hydropower development. This assessment will integrate consultations with government (CORECC), a large hydropower company (EGEMSA) and, crucially, communities living in the catchments of the lakes we have analysed. The recommendations that follow will provide information on the sustainability of existing and future hydropower schemes, how to manage water use in future decades and formulate policies that reflect the needs of all stakeholders, and the potential hazards that unstable mountain environments may pose to lives and livelihoods in future years.

This research will yield: climate, glacier and permafrost projections from present day until 2100, quantification of sediment transport, flux and storage in tropical deglaciating environments, quantitative assessments of hazard development and likely Glacial Lake Outburst Flood (GLOF) extents, and a comprehensive analysis of the social, political, cultural and economic pressures on water resource management in the region. These novel findings will be integrated to identify glacial lakes that are most suitable as reservoirs in coming decades, and that may be exploited as a hydropower resource without causing conflict between key stakeholders. The scientific data produced will be of specific interest to those working in the Andean region as well as for scientists working in other glacierised mountain regions of the world. Our methodological advances will be of interest to the technical climate and cryospheric communities, and process glaciologists and sedimentologists will be able to use the principles of our methods in their own applications elsewhere.

The main non-academic beneficiaries of the research will be 1) policy makers (e.g. project partner CORECC) in Peru concerned with securing future water availability and energy production, 2) hydropower businesses (e.g. project partner EGEMSA) with interests in securing existing energy supplies as well as identifying new sites for energy production to meet an ever increasing demand, 3) community groups (who we will work with in our study catchments) concerned about future environmental change and water supply, and 4) humanitarian aid agencies who require understanding of how continued changes in climate are likely to impact on some of the most vulnerable populations of the region. This will benefit the health of local people, and reduce the likelihood that UK-based organisations such as Department for International Development will need to fund emergency response activities as a result of unexpected changes in water supply or due to hazardous events.

Our Peruvian partners will benefit from working with new glaciological and hydrological field techniques (e.g. multibeam echosounding) as well as being trained in cutting edge modelling approaches (e.g. CAESAR, Delft3D, TOPKAPI). Through shared teaching and student supervision this knowledge will benefit future generations of scientists graduating from Peruvian universities in environmental disciplines. Additionally, our partners will benefit from enhanced profiles through joint high-impact publications and international press releases pertaining to our research outputs as they progress. Most importantly, they will benefit from the findings of our research i.e. enhanced knowledge of climate-glacier-hydrological interactions that will feed into regional management plans and provision of information to the public, and that they can build future research proposals on to expand the analysis to other regions in Peru.

Our Pathways to Impact provides full details of the methods we will employ to maximise the benefits of this research to end users. Briefly, they include focus groups and workshops that will run throughout the length of the project, provision of information summaries, infographics, educational materials and policy briefings to all relevant stakeholders in the region, and publication of all data on a University of Leeds project website for access by the academic community as well as the general public. Such forms of information dissemination can be implemented very quickly, so the timescales for the delivery of end user benefits are short (i.e. during the lifetime of the project). To ensure the impact of our research continues for some years beyond the lifetime of the project we aim to establish partnerships with both Lima-based and Cusco-based Universities to promote continued knowledge-exchange, capacity-building and potential joint PhD projects and staff exchanges.