Glacial Lakes in Peru: Evolution, Hazards and impacts of climate change.

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Glaciers in Peru are undergoing rapid recession in response to climate change and this has helped produce numerous large glacial lakes, many of which are dammed by moraines and are likely to drain catastrophically if the moraine dams fail or are overtopped. A major trigger of lake drainage is rock slides and debris flows into lakes from recently-exposed valley walls and unstable moraines. Glacial Lake Outburst Floods (GLOFs) from these lakes pose a significant hazard to communities and infrastructure and also impact water supplies in the region. In Peru, outburst floods from glacial lakes have caused ~ 32,000 deaths in the 20th century, as well as destroying vital economic infrastructure, settlements and valuable arable land. Despite the importance of these lakes, there are many unanswered questions concerning their future behaviour and the future risk of GLOFs. For instance, we do not know how many glacial lakes there are in Peru, nor whether these are growing in size, nor whether they are becoming more or less vulnerable to rapid drainage caused by rock slides and debris flows. We therefore do not know which lakes might cause GLOFs, nor whether the risk of GLOFs is increasing or decreasing. As a result, this project will answer questions concerning the past, present and future development of glacial lakes and glacier hazards in Peruvian mountains. We will produce the first complete inventory of glacial lakes in all the glaciated mountain regions of Peru, assess their changes in size over time in response to past and future glacier recession and assess changes in their vulnerability to sudden drainage. We will investigate the changing magnitude, frequency, and distribution of GLOFs under current and future global climate change; produce the first complete inventory of historical GLOFs in Peru and identify sites that have the potential to develop glacial hazards in the future. We will, for the first time, assess the risk of landslides into glacial lakes now and into the future. We will use physically-based numerical models to simulate GLOFs at sites identified as posing a high hazard and use these simulations to make hazard and flood risk predictions that can inform decision-makers in Peru. To do this we will focus on five main issues:1. Glacial lake development and GLOF inventories in the past and presentUsing literature, remote-sensing and fieldwork, we will compile an inventory of all glacial lakes and past GLOF sites in the glaciated regions of Peru. 2. Climate modellingUse the latest generation of climate models to assess mountain areas of Peru at most risk of future warming and precipitation change. This will enable us to identify areas of future lake drainage risk and we will develop a ranking of mountain areas for future risk of lake drainage.3. Assessment of lake vulnerabilityWe will identify current and likely future glacier hazards focusing on the developing landslide and debris flow risk as glaciers recede; establish the locations of potential future vulnerable lakes and potential GLOF sites.4. Model GLOFs.We will (a) establish the physical processes that govern GLOF behaviour; (b) analyse flood hydrographs of selected former GLOFs to establish downstream impacts. 5. Assess the socio-economic effects of GLOFs in Peru and GLOF prediction: We will (a) identify potential GLOF sites across Peru and assess potential socio-economic vulnerability; (b) reconstruct former GLOFs and their impacts; (c) conduct numerical simulations of downstream impacts for potential GLOF sites.This proposal is ODA compliant as it will promote the economic development of Peru by providing improved risk reduction methods that can be applied to hydropower projects and high-altitude mines as well as to local communities through relevant government agencies. The GLOF risk protocols developed in this project can be applied to other DAC-listed countries where GLOF hazards exist (e.g. Argentina)