Increasing risk of floods as glaciers recede in Central Andes

A RESEARCHER at the University of Huddersfield has examined the rate at which glaciers have been retreating in the Central Andes and says further monitoring is needed to address the growing risk of ‘Glacial Lake Outburst Floods’ to communities located downstream from the melting glacier lakes.

Dr Ryan Wilson is a Senior Lecturer in Physical Geography from the Department of Biological and Geographical Sciences at the University of Huddersfield and has recently completed a project funded by the UK’s leading public funder of environmental science, the National Environment Research Council.

The project assessed past, present and future glacial hazards in Chile such as their changing magnitude, frequency, and distribution under current and future global climate change.

The research was a collaboration between experts from six countries and has led to the first complete inventory of historical ‘Glacial Lake Outburst Floods’ in Chile. The team identified sites where glacial hazards could develop in the future to better inform planners and decision-makers in Chile and other lower income countries around the world.

“Alarmingly, more ice-dammed and moraine-dammed lakes are now developing in Chile as glaciers continue to recede. They pose an increasing threat to people’s lives, their communities and infrastructure downstream.”

Dr Ryan Wilson

The researchers used physically based numerical models to simulate outburst floods at glacier sites identified as posing a high hazard and used these to make more accurate hazard and flood risk predictions.

The risk of flooding has increased over the last century as glaciers recede in response to global climate change forming a growing number of glacial lake systems.

Outburst floods can occur anywhere that water is stored beneath or on the surface of a glacier, where water becomes ponded behind an ice front or ice dam, or where water is stored in proglacial lakes that develop between a moraine and a receding glacier margin.

Dr Wilson explained that the moraine-dammed lakes are particularly hazardous because a collapse of the moraine dam can trigger the release of large volumes of ponded water.

Glacier retreat in response to climate change has resulted in the development of numerous glacial lakes. Image Credit: Dr Ryan Wilson.

In Peru outburst floods from glacial sources have caused 32,000 deaths in the 20th century alone, as well as the destruction of essential economic infrastructure, settlements and valuable arable land. In the Nepal Himalaya, estimated costs associated with the destruction of a mature single hydropower installation caused by an outburst flood were over $500 million USD.

“Alarmingly, more ice-dammed and moraine-dammed lakes are now developing in Chile as glaciers continue to recede,” said Dr Wilson who is a member of the University’s Centre for Human and Physical Geography.

“They pose an increasing threat to people’s lives, their communities and infrastructure downstream. Our study utilised various data sources to compile a detailed record of El Morado Glaciers retreat and thinning over the past century which has highlighted the need for further monitoring of glacierised areas in the Central Andes.

“We hope that our efforts facilitate a better understanding of the downstream impacts of glacier downwasting,” he added.

Dr Wilson and the team explain the findings of the research in an article published by the peer-reviewed Journal of Glaciology.

Additional research impact

As part of a project entitled ‘Ecosystems, geomorphology and glacial hazards in the context of climate change at Exploradores glacier, XI Aysén Region, Chile’ Dr Wilson, accompanied by the University’s Dr Emma Ranson-Jones and Dr Matthew Hill, travelled to the Chilean Patagonia to conduct a two-week field campaign centred on the Exploradores Glacier, a large outlet glacier of the Northern Patagonia Icefield.

The team were joined by researchers from Chile’s Centre for Ecosystem Research in Patagonia and the University of Concepción as well as experts from the universities of Aberystwyth and Exeter.

The project, which took place in early 2020, answered key questions about past, present and future impacts of climate change in Patagonia by using both drone aerial surveying and ground sampling techniques.

The results have helped to better inform climate change adaptation policies and glacial hazard assessments in the region.

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