Walking on Water: a Journey to Peru’s Andean Water Towers / / by Jon Mackay

Dr Jon Mackay is a hydrologist at the British Geological Survey and has recently begun work, contracted from the University of Birmingham, for a NERC and Newton-fund project on Peruvian glacial retreat and water security. Here, he recounts his experience on the project’s first field campaign to the Peruvian Andes, to deploy a low-cost monitoring network to measure glacier melt and catchment hydrology in Peru’s Andean water towers...

'Water towers' in the Peruvian Andes

In November 2019, I arrived at Jorge Chavez International Airport in Lima, the starting point of a journey from the coastal lowlands of Peru to the high Andes. I had traveled here as part of the NERC and Newton-fund RAHU project led by Imperial College, where I was working with Peruvian colleagues to collect field data to help understand how climate change and rapidly retreating glaciers in the Andes are affecting the availability of fresh water. Meltwater from glacierised mountain ranges, such those in the tropical Andes, is a vital water source to communities living downstream, which is why they are often referred to as nature’s 'water towers'. On this trip, our aim was to access one of Peru’s glaciers in the Andean water towers, Suyuparina, so that we could begin measuring its rapid retreat.

Meeting with Dr Pedro Rau (project PI) and students Andres and Walescka at UTEC, Lima

I spent the first two days of my trip in Lima meeting up with the project PI, Dr Pedro Rau at Peru's University of Engineering and Technology (UTEC) and Fabian Drenkhan (Imperial College), an expert in glacier-retreat hazards. We discussed fieldwork plans and attended a conference on managing water scarcity in Lima with green infrastructure. The conference reinforced how imperative our research into future water supplies from Peru’s mountains is. In Lima, for example, water now has to be trucked in when the three mountain-fed rivers, on which the city relies, cannot meet demand.

My time in Lima also gave me the chance to sample some of Peru’s truly diverse cuisine, from ceviche (freshly caught fish cured in lime juice, chilli and onions) to chifa (traditional Chinese recipes made with Peruvian ingredients). There was no chance of going hungry!

Dusk in the Centro Histórico, Cusco

Feeling motivated from the conference, and significantly heavier after all the food, my next stop was Cusco, a city nestled in the foothills of the Andes, which was once the capital of the Inca Empire. Today it is awash with backpackers who use it as a stepping-stone to nearby Machu Picchu. I was here to meet the field team which Fabian had been busy organising back in Lima. My first field companion, Jan Baiker, met me at the airport. Originally from Switzerland, Jan now works and lives in Cusco and has a keen interest in the Andean 'bofedales' (wetlands). These bofedales are found in many glacierised valleys and are thought to be an important water store for the Andean mountains. Over the next two days we met the rest of the team which included mountain guides, glaciologists and hydrologists from UNSAAC state university. With a day to spare before we headed to Suyuparina, the team suggested I visit Macchu Pichu. Of course, I obliged.

Trucks fully loaded, as we make our way to Phinaya

By the evening of the next day, we had arrived at our home for the following five days: Phinaya, a small village situated at 4800m elevation, only a stone’s throw away from Suyuparina. Here we met the president of the local 'ronda de campesinos', David. He was interested in our work and agreed to help us over the coming days. This collaboration would prove extremely beneficial to working in the remote highlands, as the local communities are often wary of outsiders given the ongoing threat to their land and livelihoods from commercial mining companies. In David we had someone who the locals knew and respected and could speak the indigenous Quechua language to explain our reason for being there.

Alfredo drills the ice

Over the next two days we set about installing a set of ablation stakes on the Suyuparina glacier. These are wooden sticks drilled into the ice. A periodic check of the exposed length allows us to build up a record of how much the ice has melted over time. Each stake had to be drilled 6 m into the ice by hand – no mean feat at over 5000m elevation!
Walking on water, David (left) and Adrian (right) navigate Suyuparina

Working on these frozen water towers left me with a huge amount of admiration for the communities living in this remote region. The high Andes is an incredibly hostile environment. The air is bone-dry and the atmosphere desperately thin, leaving you gasping for breath while simultaneously being exposed to intense UV radiation from the sun. With the ongoing threat of dehydration, sun stroke and altitude sickness, I’d be lying if I said there wasn’t a moment or two where I was dreaming of sipping a Pisco sour back in the pleasant climes of Lima! Of course, I only had to look up and observe the jaw-dropping panoramic views to remind myself why I was here, and of the importance of our work.

For the final three days of the field trip we swapped the mountain tops for the valley bottoms and set about installing a set of boreholes in the bofedales. Some of these were fitted with low-cost ultrasonic sensors to continuously monitor the height of the water table. These data will allow us to assess how meltwater from glaciers propagates across the land surface and underground. With help from David, and some enthusiastic local landowners, we were able to install nine boreholes over the next three days.

Landowners help with the borehole installation in the lush bofedales

Now, having returned back to the UK, I am busy working to develop a glacier hydrology model of Suyuparina which we will eventually test against the field data that we’re collecting. With more field campaigns in the pipeline, the aim will be to upscale this modelling approach across some of Peru’s most important water towers and to develop new insights into Peru’s water security over the coming decades.

Jan (right) configures a low-cost water level sensor

Further reading:
RAHU project website