Geospatial data provided by drones can be crucial for emergency preparedness and infrastructure planning in Nepal. Jetliners, however, can get in the way.
Usually, getting clearance for drone flights in Nepal’s Kathmandu Valley is difficult because of the presence of the busy Tribhuvan International Airport, which serviced over 7 million passengers on nearly 130,000 flights in 2018. But the drastic reduction in flights due to COVID-19 lockdowns presented a window to map areas using drones, also called unmanned aerial vehicles (UAVs).
Uttam Pudasaini, cofounder of geospatial service provider Naxa and coordinator of social enterprise Nepal Flying Labs, said that a team of volunteers has spent hours a day on the survey project in three municipalities, including two in the Kathmandu Valley.
“If it [were] not for COVID-19, it would have been challenging to map dense core urban areas like these. At another time, it would have taken weeks of preparation,” he said, noting that recent government reforms allow municipal governments to issue permits for drones weighing less than 2 kilograms.
Pudasaini said the high-resolution images gathered by the drones can be used to prepare urban base maps, emergency preparedness plans, and evacuation routes in dense areas. He said Nepal, about 75% covered by mountains and hills, is one of the most disaster-prone areas in the world but that UAVs can make data collection less risky and more efficient.
“Flood risk modeling is an important outcome from a more accurate topographical map, and a digital elevation model can be generated using the high-resolution images,” he said, adding that heritage sites, including ancient temples, have also been documented by the project.
“For a country like Nepal that is struggling with many challenges, I feel glad that local governments are supporting this work,” Pudasaini said.
Siddhanta Neupane, an information and communications technology officer in Nepal’s Changunarayan municipality, said the local government has wanted to use drones for years. Changunarayan is home to about 54,000 people on the rural-urban fringe of the Kathmandu Valley.
Neupane and Changunarayan mayor Som Prasad Mishra got in touch with Pudasaini in March. Since then, 21 senseFly eBee drone flights have taken 1,828 photos across about 35 square kilometers.
“We are looking to develop an interactive GIS [geographic information system] system for the municipality, based on the drone data…most of the land is very steep, so we are looking for ways to mitigate landslides or monsoon flooding,” Neupane said.
Markus Gerke, a professor at the Technical University of Braunschweig in Germany and an expert in photogrammetry, said that optical cameras on UAVs like the ones used in Nepal have a resolution of 5–10 centimeters per pixel, far higher than the 10-meter-per-pixel resolution from some open-source satellite data.
“This means details like housing situation (even roofing type), infrastructure health, even curbstones can be seen in the UAV-based images,” he said.
Uma Shankar Panday, a computer engineer and assistant professor at Kathmandu University, said that once the data-gathering phase is complete (it’s on hold until the monsoon season is over), data processing will take a matter of days, using either Kathmandu University’s supercomputer or cloud computing solutions, plus the signing of agreements and other official formalities.
Panday said drone projects like this are vital for Nepal. “It’s good to have ideas from outside, but it is the local ideas that are most easily implemented.”
—Andrew J. Wight (@ligaze), Science Writer