Patagonia and the central Andes – February 2017

Fieldwork location: Lago Chileno (Patagonia) and Laguna El Morado (central Andes)

Date: January 28th – February 16th 2017

Team: Dr Ryan Wilson (Aberystwyth University), Dr Stephan Harrison (University of Exeter), Dr John Reynolds (Reynolds International Ltd.), Olaf Wuendrich (Mountain guide – ColibriVentura) and Jammie Valdivia (Logistics and support – ColibriVentura)

Summary:
Between the 28th January and 16th February 2017 team members from the Glacial Hazards in Chile project conducted fieldwork in the central Andes and southern Patagonia. The ultimate aim of the expedition was to better understand the physical characteristics of glacial lakes in Chile and the processes which result, in some cases, in large glacial lake outburst floods (GLOFs). The initial task of identifying possible field sites was in itself quite challenging with Chile containing >3000 glacial lakes distributed throughout the northern, central and Patagonian Andes. In the end, two lakes were chosen based on scientific interest and accessibility. The first of these, Lake Chileno in southern Patagonia, had recently produced a large GLOF which had resulted in significant damage to the downstream floodplain, and the second, Laguna El Morado, was identified as one of the fastest growing lakes in the central Andes. In order to survey these two lakes and their surroundings, the team took with them a fixed wing drone and dGPS system (very kindly lent to the team by Professor Alun Hubbard from Aberystwyth University and meticulously put together and packaged by his PhD student Jonathan Ryan), a DJI quadcopter and a custom built bathymetry boat (designed and built by Dr Mark Neal from Aberystwyth University). Thanking their lucky stars that the surveying equipment together with the copious number Li-po batteries needed to power it all had arrived safe and intact from the UK, the expedition began in Santiago de Chile. From here the team boarded an internal flight to Balmaceda where they met up with Olaf and spent a night in nearby Coyhaique. We cannot speak highly enough of Olaf and Jammie who run the mountaineering company ColibriVentura. Together they organised all our necessary permits, managed our expedition logistics and mountain equipment needs and most importantly led us safely in and out of both field sites. The expedition could not have been a success without them and we highly recommend them to anybody planning outdoor adventures in Chile. For more details see:

ColibriVentura: http://colibriventura.com


Location of the Laguna El Morado and Chileno Valley field sites in Chile.


Harvest time along the road from Balmaceda airport to Coyhaique, Patagonia.

Chileno valley – Patagonia: 31st January to 6th February 2017

Bright and early on 31st January we began our southerly travels towards camp site 1, driving first along the scenic Carretera Austral to Puerto Río Tranquilo, situated on the shores of Lake General Carrera, before checking ourselves in at the local police station and heading west towards the terminal moraines of Exploradores glacier. Exploradores glacier flows down from the slopes of Monte San Valentín and is located at the northern tip of the Northern Patagonia Icefield. Here, we met our support team (headed by the excellent Marcos) and then embarked on a 4 hour trek through thick temperate forest, transporting all the equipment to camp site 1, located around 1 km from the mouth the Chileno valley. Where possible, we trekked along the crest of the large lateral moraines impounding the main glacier snout which offered excellent views of the now downwasting and heavily debris covered ice surface. Fully rested, the next day we entered the Chileno valley itself and established base camp within the floodplain of the recent GLOF event. The Chileno valley, once a densely vegetated meadow, was completely re-worked by the recent GLOF event. Large boulders, sediment, trees and debris now lay strewn across the floodplain and the post-GLOF river channel has changed course and lowered in elevation by several meters in some places. Topographic narrowings located towards the head and mouth of the valley have also been heavily eroded and are now considerably wider than their original state. Despite the scene of destruction in the valley below, when we reached the GLOF source, Lake Chileno, on the 2nd February we found a relatively tranquil and benign site with no initial sign of what might have triggered the GLOF evident. However, the water marks visible on the surrounding rocks suggest the lake level has dropped considerably. Over the coming months we will conduct a forensic analysis of the Chileno valley using elevation models produced from the drone imagery acquired, high-resolution satellite imagery, meteorological data and the lake bathymetry data collected to try to piece together clues as to what triggered the GLOF event. This information will help us understand the trigger mechanisms of past GLOF events in Patagonia and better estimate the susceptibility of future events in this region.


On our way to Puerto Rio Tranquilo, the turquoise waters of Lake General Carrera can be seen in the background.


Trekking through temperate forest on our way to basecamp in the Chileno valley, Patagonia. Olaf leads the group at the front whilst Stephan and the others follow behind.


As the main snout continues to downwaste, a number of lakes have developed around the margins of Exploradores glacier. The team pass by one of these ice-marginal lakes whilst trekking to the mouth of the Chileno valley.


Lush vegetation beside the debris-covered ice of the main snout of Exploradores glacier.


Transporting the bathymetry boat on foot through vegetation on our way to the Chileno valley.


Camping rest stop on our way to Chileno valley with Exploradores glacier looming in the background.


The team reach the mouth of the Chileno valley, heavily scarred and eroded as a result of a large GLOF event.


GLOF floodplain, Chileno valley.


John and Stephan wind their way around large boulders and across thick sediment deposits transported by the recent GLOF event.


Shoreline of Lake Chileno, the source of the recent GLOF event.

Defying the weatherman’s predictions, sunshine and clear skies prevailed from 3rd February onwards prompting a dash to get the fixed drone image acquisitions done and dusted. However, our good luck temporally faulted when……disaster struck. Having successfully launched the fixed wing drone, it quickly became apparent that there was a fault with the steering mechanism and upon attempting to land the drone veered off course and wallop……went full speed ahead into a large tree nestled in the valley side! Fearing the worst, we trudged off into the forest to retrieve what was left of the drone but to our surprise found it almost intact with only a few scratches and scrapes to show for its impact (something to be said for the strength of polystyrene). Disaster averted, the steering issue was resolved and the fixed wing acquisition missions were successfully completed over the next the days. In addition, more detailed aerial surveys were conducted of the upper valley using the quadcopter drone and Ground Control Points (GCPs) were surveyed using a dGPS systems. These GCPs will be used to aid the image orientation process once back in the office. The bathymetry surveys were also a success and the remote-controlled system performed well. However, if you do happen to be standing around in deepest Patagonia for prolonged periods of time with a remote control in your hand, be warned, there are plenty of overzealous horse fly’s about intent on distracting you : ) A cork hat is certainly recommended!


The calving front of Chileno glacier with its steep-sided tributary in the background.


Bathymetry boat surveying Lake Chileno.


Aerial drone imagery of Lake Chileno looking down valley towards Exploradores glacier.


Aerial drone imagery of the Chileno valley. The newly incised river channel towards the left drains into a large ice-marginal lake.


Ground control points whose locations where surveying by a dGPS system will be used to orientate aerial drone imagery acquired.


Mind bending oblique aerial image of Exploradores glacier.

Laguna El Morado – central Andes: February 10th to February 12th

Having successfully trekked out of the Chileno valley and made our way back up the Carretera Austral to Coyhaique, we arrived back in Santiago on 9th February. The next day we hired a 4×4 and began our ascent up the high central Andes to the Refugio Lo Valdés which would be our base for the next 3 days. Located in the Cajón del Maipo, around 70 km east of Santiago, the dry and arid landscape surrounding the refugio was in stark contrast to Patagonia, with high mountain peaks and large rocky spree slopes replacing lush forests and lakes. The area receives a steady flow of tourists throughout summer, owing to the proximity of the El Morado Natural Monument, and was easily accessible using the good quality roads that feed the several large mining operations located further up valley. The Laguna el Morado, our second field site, is located at around 3250 m (a.s.l.) and is within the valley Las Arenas. The lagoon is accessible from the Refugio Lo Valdés first by road, driving for an hour up-valley, followed by a fairly pleasant 2 hour trek up the mountain side towards Cerro El Morado. With an area of roughly 0.14 km2, Laguna el Morado is small compared to Lake Chileno but has grown in size recently due to the retreat of Colgante del Morado glacier which actively calves into the lagoon. Initial assessments of the drone and lake bathymetry data acquired at this site suggests that that the lagoon poses no imminent threat of outburst and the downstream GLOF risk is fairly low. However, outburst risks associated with specific glacial
lakes can evolve through time and continual vigilance is needed. The main trunk of Colgante del Morado glacier, for example, flows over a steep sided slope and, if the snout continues to retreat, this portion of the glacier may hang ominously over the lagoon posing a future ice avalanche threat. Such scenarios will be examined by the team over the
coming months as part of a more detailed GLOF risk assessment of the central Andes.


Road to Refugio Lo Valdés with Volcán San José in the background.


Refugio Lo Valdés, Cajón del Maipo, Chilean central Andes.


Stephan leads the way up to Laguna El Morado.


Colgante del Morado glacier calving into Laguna El Morado, San José de Maipo, Chile.


Bathymetry survey of Laguna El Morado.


Aerial drone image of moraine dam impounding Laguna El Morado. Glacial push-moraines are visible running parallel to the moraine crest.


Ryan (left), Olaf (centre) and Stephan prior to the final ascent.


Our field efforts have been featured in the March 2017 edition of Science:

Chile’s glacial lakes pose newly recognized flood threat