Model of Hazards from GLOF to Huaraz, Peru

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By Daene C. McKinney, Marcelo Somos-Valenzuela, Rachel Chisolm, and Denny Rivas 

University of Texas at Austin, March 2014 

We modeled the complete Glacial Lake Outburst Flood (GLOF) process chain from the top of the glacier above Laguna Palcacocha to the city of Huaraz. The results show that Huaraz is exposed to significant flood hazards.

ABSTRACT

 

One of the consequences of recent glacier recession is the formation and rapid growth of lakes formed at the snout of glaciers. One risk is that moraines damming these glacial lakes could fail releasing a huge volume of water and creating a glacial lake outburst flood. This happened December 12, 1941, at Lake Palcacocha, Peru, flooding the city of Huaraz and killing several thousand people. Recently Lake Palcacocha has been declared in a state of emergency state because its volume has again reached dangerous levels, threatening a flood that would quickly reach Huaraz causing major devastation and potentially loss of life. An analysis has been performed of the glacial hazards for the city of Huaraz from Lake Palcacocha. This analysis consists of physical models of each process in the chain of events that results in a glacial lake outburst flood: rock and ice avalanche; wave generation, propagation and moraine overtopping; terminal moraine breaching and draining of the lake; and downstream inundation and impacts in the city of Huaraz. A worst-case scenario was analyzed starting with a large avalanche of 3 million m3 that produces a 35-40 m surge wave in Lake Palcacocha and initiates an erosional process in the terminal moraine that could drain over 16 million m3 of water from the lake. The flood wave from this event would take about one hour to reach Huaraz, exposing an area of 5 km2 to inundation greater than 20 cm, including portions of the city near the Quillcay and Santa Rivers where much of the commerce and infrastructure are located in the very high hazard zone.

The complete paper is available from Center for Research in Water Resources, University of Texas at Austin, Austin, Texas USA

Attached below are the slides from a presentation to the city of Huaraz in March, 2014. (49MB)

 

Document Format: 
Huaraz GLOF presentation
Location: 
Peru
Where we work: