Articles | Volume 14, issue 12
Research article
05 Dec 2014
Research article |  | 05 Dec 2014

Moraine-dammed lake failures in Patagonia and assessment of outburst susceptibility in the Baker Basin

P. Iribarren Anacona, K.P. Norton, and A. Mackintosh

Abstract. Glacier retreat since the Little Ice Age has resulted in the development or expansion of hundreds of glacial lakes in Patagonia. Some of these lakes have produced large (≥ 106 m3) Glacial Lake Outburst Floods (GLOFs) damaging inhabited areas. GLOF hazard studies in Patagonia have been mainly based on the analysis of short-term series (≤ 50 years) of flood data and until now no attempt has been made to identify the relative susceptibility of lakes to failure. Power schemes and associated infrastructure are planned for Patagonian basins that have historically been affected by GLOFs, and we now require a thorough understanding of the characteristics of dangerous lakes in order to assist with hazard assessment and planning. In this paper, the conditioning factors of 16 outbursts from moraine-dammed lakes in Patagonia were analysed. These data were used to develop a classification scheme designed to assess outburst susceptibility, based on image classification techniques, flow routine algorithms and the Analytical Hierarchy Process. This scheme was applied to the Baker Basin, Chile, where at least seven moraine-dammed lakes have failed in historic time. We identified 386 moraine-dammed lakes in the Baker Basin of which 28 were classified with high or very high outburst susceptibility. Commonly, lakes with high outburst susceptibility are in contact with glaciers and have moderate (> 8°) to steep (> 15°) dam outlet slopes, akin to failed lakes in Patagonia. The proposed classification scheme is suitable for first-order GLOF hazard assessments in this region. However, rapidly changing glaciers in Patagonia make detailed analysis and monitoring of hazardous lakes and glaciated areas upstream from inhabited areas or critical infrastructure necessary, in order to better prepare for hazards emerging from an evolving cryosphere.

Short summary
In Patagonia at least 16 moraine-dammed lakes have failed in historical time. Commonly failed lakes were in contact with glaciers at the time of failure and had moderate (≥ 8°) to steep (≥15°) outlet slopes. Seven failed lakes are located in the Baker Basin, Chilean Patagonia, were hydro-electric generation plants are planned. We assessed the outburst susceptibility of moraine-dammed lakes in the Baker Basin and identified 28 lakes with high or very high outburst susceptibility.
Final-revised paper