Multi-Temporal Analysis of the Glacier Retreat Using Landsat Satellite Images in the Nevado of the Ampay National Sanctuary, Peru

Glaciers are humanity\u27s most extraordinary water reservoirs, covering approximately 10% of the total Earth surface. The investigation of the retreat of the glacier surface in the Ampay National Sanctuary is carried out using the historical series of Landsat images and applying the normalized snow differential index between the years 1991 to 2017. The meteorological data from the Tamburco and Abancay stations have been considered to determine the deglaciation and quantify the retreat of the Ampay glacier. The supervised classification spatial visualization method for the Landsat 2 Multispectral Scanner image and the normalized snow differential index have been used to determine the glacier cover area with Landsat 5, Landsat 7, and Landsat 8 Operational Land Imager/Thermal Infrared Sensor images. The results show a significant decrease in the surface of the Ampay glacier due to the increase in temperature. The surface of the Ampay glacier in 1991 was 2.13 km2 and in 2017 – 1.09 km2, showing a loss of 1.04 km2 (48.92%) as a consequence of significant climate variability (temperature and precipitation). In 2015, an apparent accumulation of snow was recorded on the Ampay glacier, reaching 2.595 km2, but in the following years, the glacier surface has been decreasing until it reached 1.086 km2 in 2017. It is concluded that the glacial retreat of the Ampay National Sanctuary in the last 25 years with a tendency to continuous deglaciation puts the water resource at risk