Investigating glacial recession in the Cordillera Blanca of Peru using Landsat imagery

The high peaks of the Cordillera Blanca in the Ancash region of Peru contain the highest concentration of tropical glaciers in the world. These glaciers function as an important water supply during the region’s winter season when precipitation is low. Climate change is accelerating the mass balance loss of these glaciers, and receding ice has exposed sulfide-rich geologic formations that influence the chemistry of glacial runoff. In an effort to predict future change, glacial recession in the Cordillera Blanca was analyzed through the analysis and classification of Landsat thematic mapper (TM) imagery acquired over a multi-year period. Snow and ice coverage was extracted from Landsat images through the implementation of a Normalized Differenced Snow Index (NDSI), which utilized the green (TM band 2) and short wave infrared (TM band 5) portions of the electromagnetic spectrum. Additionally, a water mask was created to reduce noise and misclassification associated with alpine streams and glacial lakes. The extent of snow and ice was calculated for each year to produce a linear regression and examine trends in coverage loss throughout the study period. Trends in glacial recession were then compared to water quality data from several valleys in the Cordillera Blanca that was gathered between the years of 2012-2016 on yearly research expeditions. This research could shed light on the implications of glacial recession and suggest a mechanism for declining water quality in the Ancash region of Peru