Risk analysis and reconstruction of the 1934 glacial lake outburst flood event in the Plomo basin (33º S), Central Andes of Argentina.

CORREAS GONZÁLEZ M.; MOREIRAS S.M.; MERGILI, M.

Encuentro; IAL-IPA 2022 joint meeting; 2022

In the last 230 years, the Plomo River (33º S, 70º W) was dammed at least three times by surges of the Glaciar Grande del Nevado del Plomo (GGNP) . The temporary lakes of ca. 60 x 106 m3 generated six Glacial Lake Outburst Floods (GLOFs) of different magnitudes (from 350 to 3,000 m3/s). Almost one century after the most catastrophic event happened on the 10th January of 1934, many changes in land use and an increase in human activities along the Mendoza River valley have occurred, exposing new elements to this threat. This research aims to reconstruct the main characteristics of the 1934 and 1985 temporary lakes and the outburst floods generated along the course of the Plomo River, tributary of the Tupungato River, to assess GLOF risk along the Mendoza River valley. Based on historical records, old topographic maps, and remote sensing, we elaborate the hazard and vulnerability thematic maps. The hazard (H) map is developed using data from the 1934 catastrophic event, whereas the vulnerability (V) is evaluated considering the current land use along the historically affected valley. Finally, GLOF risk (R) is assessed by the classical approach of R=HxV and the overlapping of hazard and vulnerability maps. In a second step, general flooding dynamics are being modeled to reconstruct the 1934 major event using the physically-based multi-phase mass flow model r.avaflow. A plausible flood reconstruction will be crucial for a better understanding of the flow dynamics. Our results show that increasing human activity in the valley and new investments aggravate the exposure and vulnerability against this potential hazard. In summary, our results will help to better understand not only GLOFs from the GGNP, but also the possible impact of GLOFs from other glaciers in the region which have experienced extraordinary advances in the past .