When a flood from a mountain lake threatened to swamp this Andean town early one morning in April 2010, Víctor Rodríguez was the only person who knew. From his hut on a plain below the mountain, he heard the jet-like rumble as a block of ice calved off a glacier and crashed into the lake.

The force of the fall produced a wave that swept over the earthen dike around the water body, called Lake 513, and cascaded down the steep slope. Rodríguez watched as the water swirled across the plain, swamping the catchment for the municipal water system, where he worked as caretaker.

Picking up speed as it funneled into the Chucchún River, the torrent of water carrying mud and boulders swept away crops, livestock and some buildings. But it stopped just short of this town of about 12,000 people beside the Santa River, at the foot of Peru’s Cordillera Blanca, a popular area for climbers, hikers and tourists. (See “Falling ice from glacier gives Peru climate-change preview”—EcoAméricas, April ’10.)

With climate change increasing the threat of such hazards, the Swiss government’s development agency, a Peruvian nonprofit and a Swiss university teamed up to develop a high-tech early-warning system. By the end of 2013, lakeside sensors and cameras were in place above Carhuaz, with relay antennae that could transmit information quickly to a command center in the municipal offices. Once its kinks were worked out, organizers of the project hoped, the system could serve as a model for other towns that lie below glacial lakes.

Then disaster struck again, this time in the form of a drought. Not only was rain scarce, but, an unseasonal frost damaged crops. Rumors spread among residents of
farming communities around Carhuaz that the monitoring equipment at Lake 513 was preventing clouds from forming. Early one morning last November, several hundred people from the largely indigenous communities, where traditional Andean beliefs still hold sway, trekked up to the lake and tore down the system.

Within a week, it rained.

The events raise questions about how to ensure that in areas where rural residents distrust technology, systems can be created to reliably warn those potentially in the path of Carhuaz-style deluges, known as glacial lake outburst floods, or GLOFs. It also highlights tensions between growing urban areas and their rural neighbors—tensions that could deepen as dense development encroaches on agricultural land and city dwellers demand a larger share of water from threatened sources.

The destruction of the Carhuaz early-warning equipment came as a shock to the system’s developers; but in hindsight, signs of discontent had been building.

During workshops in 2012, residents said they felt unprotected against outburst floods like the one in 2010, says Karen Price Ríos of CARE Peru, a nonprofit development organization that has been active in the area for several years. Price worked with local communities on the three-year early-warning project, which was funded by the Swiss aid agency Cosude and supported by researchers from the University of Zurich, who study glaciers and water in that region of Peru.

The researchers drew up a risk map, showing the areas in varying degrees of danger from a mudslide like that of 2010, and devised evacuation routes, marking them with signs. The centerpiece of the project was the early-warning system on Mount Hualcán. If a block of ice broke from the glacier and crashed into Lake 513, it would trigger sensors that would turn on cameras and send an alert to local officials. They could then check the images from the cameras to verify the flood, then sound an alarm. The early warning would give local residents about half an hour to evacuate to safety zones out of range of the type of flood and mudslide that occurred in 2010.

One monitoring station—with a solar panel, antenna,
battery box, cameras and motion sensors called geophones—was installed at Lake 513, some 4,491 meters (14,734 feet) above sea level, with additional geophones several hundred meters higher. A repeater down in the valley boosted the signal before it reached the municipal offices in Carhuaz, at 2,641 meters (8,665 feet) above sea level. Another monitoring station—on the plain below Mount Hualcán, beside the upper part of a system of irrigation canals and the intake for Carhuaz’s drinking water system—gathered water-level and flow data from the Chucchún River.

The system was installed in 2012 and presented at the International Glacier and Mountain Ecosystems Forum in Huaraz, Peru, in July 2013 as a pilot that could serve as a model for other Andean towns threatened by outburst floods. In 2015, CARE’s Glacier Project in Carhuaz officially ended and the system was turned over to the Carhuaz provincial government headed by Mayor Jesús Caballero García, who had taken office in January. Though the head of the local disaster management office could monitor the system, the government lacked funds for specialized maintenance, Caballero says.

“We didn’t have personnel trained to evaluate the entire system and say whether it was functioning,” he says.

In 2016, lack of rain became a more pressing concern than an outburst flood for farmers in the rural communities along the Santa River and its tributaries, including the Chucchún. It is not clear when people began to blame the equipment on Mount Hualcán, but in February 2016, one local leader asked Caballero to remove it. Two months later, vandals stole the cameras from the lakeside monitoring station. It might have been an ordinary theft, but observers note that it would be difficult to fence the specialized cameras in local black markets.

CARE and Cosude agreed to replace the stolen cameras, but before arrangements could be made, leaders from several surrounding communities demanded again that the equipment be removed, as farmers reeled from both drought and an out-of-season frost.

A town hall-style meeting last year was scheduled for the end of November to discuss the problem, but on Nov. 24, several hundred people from surrounding communities marched up the mountain to the lake. Caballero says he accompanied the group to persuade the protesters to leave the equipment in place, but after a few tense hours, they tore down what was left of the equipment beside the lake and the monitoring station on the plain below.

A few months later, some embarrassment seemed to have set in. It is difficult to find people who admit to helping dismantle the equipment, although some will talk about beliefs that led to the action—that the equipment “blew the clouds away,” or that it might have been placed there to benefit some outside interest, such as a mining company.

That was not the first time equipment had been blamed for unfavorable weather near Carhuaz. Nearly two decades ago, farmers demanded that another researcher remove meteorological monitoring devices from the mountain, and scientists tell stories of similar incidents in other parts of Peru, as well as in Colombia and Bolivia.

“People have a very close relationship with the mountains,” says geographer Christian Huggel of the University of Zurich. “The snow-capped peaks are living beings.”

With time, however, a more complex picture of the tensions over the Carhuaz early-warning system has emerged.

In workshops with Glacier Project staff shortly after the 2010 outburst flood, people in both Carhuaz and the surrounding farming communities identified floods as the greatest natural hazard they faced. Climate change, it seemed, was on everyone’s mind. And in a study conducted during 2012-14, sociologist Luis Vicuña found that when discussing risks, people in the farming communities around Carhuaz spoke of climate change in virtually the same terms they had heard in the workshops.

But when Vicuña changed the question slightly, he found that farmers were actually more concerned about their supply of irrigation water—whether they would continue to have enough water, and how much of a say they would have in managing it.

The water worries reflected tensions between the farming communities and the town of Carhuaz, where population growth has pushed the urban limits farther into the countryside. Farms have been shrinking as demand for food has been increasing, Vicuña says.

The expanding urban population has increased demand for drinking water, too, says Lindón Mejía, who manages the city’s water and sanitation system. Since the timing of the Glacier Project happened to coincide with plans to expand Carhuaz’s potable water system, the drought may have exacerbated fears of more water being used for the urban area.

At the heart of those fears is concern that less irrigation water will be available for rural residents, who in addition face a lower risk of outburst-flood damage than town dwellers since they live on higher ground. Such tensions, combined with local urban and rural political dynamics, probably created fertile ground for rumors that led the crowd to tear down the monitoring stations, Vicuña says.

Glacier Project staff made a concerted effort to forge consensus, meeting with people in the urban area and in the villages closest to Carhuaz. But many of those who climbed the mountain to pull down the monitoring equipment were from villages outside the area that would be in the path of an outburst flood from Lake 513. They knew little about the system and did not stand to benefit from it, Vicuña says. CARE and Cosude decided not to reinstall the system at Lake 513, although Cosude will finance a similar system around Santa Teresa, in the southern Andean region of Cusco.

Meanwhile, researchers, project staff and government officials puzzle over what could be done differently next time.

The question will only become more critical. The Andes Mountains are home to the largest expanse of tropical glaciers in the world, but the ice fields have been shrinking significantly over the past half-century. The bellwethers are Bolivia’s famed Chacaltaya—now bare rock where a ski resort once stood—and Peru’s Pastoruri, which has been converted from an emblematic glacier to an illustrative stop on a climate-change tour.

A warmer climate means glaciers will continue to recede, and their meltwater will feed lakes high above valley towns. This, in turn, will heighten the risk of outburst floods.

Worries about that risks already weigh on Huaraz, a city of more than 100,000 people about half an hour from Carhuaz. About one-third of the city was devastated and an estimated 2,000 people died in an outburst flood from Lake Palcacocha in 1941. About 50,000 people in Huaraz now live in the path of a potential outburst flood, says Daene McKinney of the University of Texas, who has modeled the complex movement of water, soil and rock to create a map of the hazard there.

Like Carhuaz, the area around Huaraz is marked by an urban-rural divide, with people in the urban zone of Huaraz more concerned about a possible outburst flood, while farmers are more worried about access to water. A proposal for an early warning system is wending its way through government funding channels, McKinney says, although tourism operators worry that calling attention to the risk could put a dent in Huaraz’s important tourist trade.

Any such project, whether in Huaraz or elsewhere, should involve more extensive studies of local communities and political positions, Vicuña says.

Another possibility might be to turn local residents into citizen scientists. Anthropologist Ben Orlove of Columbia University says the citizen scientists might be invited to help gather data and become part of the study, rather than simply witnessing the installation of instruments they don’t understand.

And when new local government officials take office, attention must be paid to ensure that they will take responsibility for early-warning systems installed by their predecessors, says Martin Jaggi, Cosude’s director of global cooperation programs.

Despite the dismantling of its early-warning equipment, Carhuaz is nevertheless better protected than it was before, Huggel says. Government officials and residents are more aware of the outburst-flood risks, evacuation routes are clear, and the personnel who keep watch over the city’s drinking water intake 24 hours a day can radio a message to the town in case of a flood.

It is estimated that town residents can expect warnings 10 to 15 minutes before outburst waters arrive. That’s significantly less time to evacuate than the 30 minutes promised under the high-tech system originally envisioned, but the current plan still could be efficient, Huggel says. He adds: “The early warning system is much more than just instruments.”