Climate change impacts and water security in the Cordillera Blanca, Peru
Chisolm, Rachel Elizabeth
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This dissertation addresses two aspects of climate change impacts on water resources in the Cordillera Blanca mountain range in Ancash, Peru: glacial lake outburst floods (GLOFs) and water availability. Peru is one of the countries most impacted by climate change, largely due to the abundance of glaciers that play an integral role in the water resources systems of the Peruvian Andes and the coastal region. A warming climate has resulted in the accelerated retreat of many of these glaciers in recent decades. The two greatest impacts of climate change on water security in the Cordillera Blanca are GLOFs and water scarcity during the dry season. This dissertation studies both of these facets of water security in the Cordillera Blanca, Peru. As new glacial lakes emerge and existing lakes continue to grow, they pose an increasing risk of GLOFs that can be catastrophic to the communities living downstream. In this work, particular emphasis is placed on the upper watershed processes that typically comprise a GLOF event. Dynamics of avalanche-generated impulse waves are investigated through three-dimensional hydrodynamic lake simulations of potential GLOF scenarios at Lake Palcacocha, Peru. At Artesonraju Glacier, an emerging lake has recently formed and continues to grow as the glacier retreats. Future lake volumes are projected from ground penetrating radar measurements of ice thickness. With these projections of future lake conditions, possible future hazard conditions are studied at vi Artesonraju, and a new analytical method is presented for calculating approximate overtopping volumes from avalanche-generated waves. Climate change impacts on water availability have been studied through the analysis of approximately 50 years of precipitation data from a weather station in the Cordillera Blanca. These data have been analyzed for trends and changes in variability in precipitation patterns. As a foundation for climate-resilient development, precipitation trends and changes in variability have been linked to possible impacts on agricultural projects. The results of the precipitation data analysis were compared to studies of local perceptions of climate change, and it was concluded that people’s perceptions of change in precipitation patterns often do not reflect the trends observed in the gauged data.