Future scenerios of glacier lake outburst flow occurrence over Andean tropical areas in Peru: Palcacoha lake case.

Abstract:

At December 13th, 1941, changes in the climatic variables, over tropical mountain regions, might cause an overflow of the Palcacocha lake, which impacted the center Peruvian mountain region where thousands of people perished. Palcacoha glacier lake is actually a representative case of dangerous Peruvian Andes glacier lakes. In a context of climate change, here is presented the results of relating precipitation (Pr), max (Tx), min (Tn), and mean air temperature (Ta) variables against Palcacocha lake volume using observed daily data since 2017-2019. Later, ETA regional climate model output data were bias corrected with observed data to analyze historical and future (RCP4.6 and RCP8.5) scenarios, from 1961 to the end of the 21st century, from three global climate models. Additionally, the glacial area around Palcacocha was calculated and related with bias corrected ERA5 reanalysis product over 1979-2019 period. The results showed that Ta is linear related with glacial area retreat, as several previously researches had shown, in this context Ta can be used as proxy to runoff from glacier areas. Then Ta was used as proxy to amount of (superficial and underground) freshwater release from glacier areas. Another analysis showed that anomalies of Ta is positively and linearly correlated with the glacier lake volume anomalies (R²>0.32, P-value>0.001). On the other hand, Pr has not presented significant tendency and linear correlation against lake volume, then it can´t be considered a volume predictor. Using the empirical linear relationship between Ta and lake volume, was assessed the potential future lake volume levels for the RCP4.5 and RCP8.5. The results pointing out that the increase in the lake volume would generate that the lake level increase (2080-2099) will be between 13 to 21% than current level. Several glacier lakes over Peruvian Andes will suffer similar increment due to future state of Ta. Hence, several tropical glacier lakes will increment in volume, and these would generate increase in glacier lakes outburst flow occurrence, due to more potential energy will be collected through time in this glacier lakes. Those results are showing significant negative impacts due to future climate change conditions, and this research helps to prevent future natural hazards.