Science From Above

About 5,000 meters high in the Peruvian Andes, scientists are mapping glaciers and wetlands in the Cordillera Blanca mountain range with 10-centimeter precision to gauge how climate change will affect the half-million local residents who rely in part on those glaciers for their water supply.

Their strategy provides a template for research teams that are investigating water security in other areas of the world with much larger populations, including China and India.

The groundwater system would have been very hard to obtain without special high-altitude unmanned aerial vehicles (UAVs) that Wigmore designed and built, and time-lapse thermal camera systems that colleague Jeffrey McKenzie at McGill University developed.

In the Cordillera Blanca, clouds block satellite views for all but a few weeks a year, and the terrain is too irregular to take reliable ice surface measurements by hand. Traditionally, scientists’ only other option would be to fly remote sensing equipment over the ice in an airplane – an endeavor that is not only expensive, but dangerous given the mountains’ sharp changes in elevation.

The Ohio State UAVs have a 10-centimeter resolution, work despite frequently cloudy conditions in the mountains of Peru and cost a few thousand dollars each. In contrast, satellites provide a half-meter resolution at best, work only during the two months a year when the region is relatively cloud-free and cost millions of dollars.

Whereas airplane surveys cost hundreds of thousands of dollars, and satellites cost millions, he can build a UAV for around $4,000.

Wigmore described the Llaca Glacier’s ice loss and collapse of the calving front as more dramatic than he would have expected.

Wigmore also presented measurements that suggest a key glacier in the region’s Llaca Valley is changing rapidly. He recorded an average of 0.7 meters of thinning in one year, with a maximum of 18 meters of loss in some locations. For example, an ice cliff at the leading edge of the glacier collapsed over a two-week period early in 2015.