Reconstruction of the 1941 GLOF process chain at Lake Palcacocha (Cordillera Blanca, Peru)
- Author(s)
- Martin Mergili, Shiva Prasad Pudasaini, Adam Emmer, Jan-Thomas Fischer, Alejo Cochachin, Holger Frey
- Abstract
The Cordillera Blanca in Peru has been the scene of rapid deglaciation for many decades. One of numerous lakes formed in the front of the retreating glaciers is the moraine-dammed Lake Palcacocha, which drained suddenly due to an unknown cause in 1941. The resulting Glacial Lake Outburst Flood (GLOF) led to dam failure and complete drainage of Lake Jircacocha downstream, and to major destruction and thousands of fatalities in the city of Huaráz at a distance of 23 km. We chose an integrated approach to revisit the 1941 event in terms of topographic reconstruction and numerical back-calculation with the GIS-based open-source mass flow/process chain simulation framework r.avaflow, which builds on an enhanced version of the Pudasaini (2012) two-phase flow model. Thereby we consider four scenarios: (A) and (AX) breach of the moraine dam of Lake Palcacocha due to retrogressive erosion, assuming two different fluid characteristics; (B) failure of the moraine dam caused by the impact of a landslide on the lake; and (C) geomechanical failure and collapse of the moraine dam. The simulations largely yield empirically adequate results with physically plausible parameters, taking the documentation of the 1941 event and previous calculations of future scenarios as reference. Most simulation scenarios indicate travel times between 36 and 70 min to reach Huaráz, accompanied with peak discharges above 10 000 m3 s−1. The results of the scenarios indicate that the most likely initiation mechanism would be retrogressive erosion, possibly triggered by a minor impact wave and/or facilitated by a weak stability condition of the moraine dam. However, the involvement of Lake Jircacocha disguises part of the signal of process initiation farther downstream. Predictive simulations of possible future events have to be based on a larger set of back-calculated GLOF process chains, taking into account the expected parameter uncertainties and appropriate strategies to deal with critical threshold effects.
- Organisation(s)
- Department of Geography and Regional Research
- External organisation(s)
- Rheinische Friedrich-Wilhelms-Universität Bonn, Bundesforschungs- und Ausbildungszentrum für Wald, Naturgefahren und Landschaft (BFW), Universität Zürich (UZH), Autoridad Nacional del Agua, Universität für Bodenkultur Wien, Czech Academy of Sciences
- Journal
- Hydrology and Earth System Sciences
- Volume
- 24
- Pages
- 93-114
- No. of pages
- 22
- ISSN
- 1027-5606
- DOI
- https://doi.org/10.5194/hess-24-93-2020
- Publication date
- 01-2020
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105404 Geomorphology, 105902 Natural hazards, 102009 Computer simulation
- Keywords
- ASJC Scopus subject areas
- Water Science and Technology, Earth and Planetary Sciences (miscellaneous)
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/reconstruction-of-the-1941-glof-process-chain-at-lake-palcacocha-cordillera-blanca-peru(f01e9154-0109-490d-8227-655b7e4c0813).html