From a Cessna 441 Conquest aircraft, a study team is using Light Detection and Ranging (LiDAR) technology to conduct digital mapping of Palau’s terrain, which will be used to tackle threats from natural disasters.
The digital mapping from the skies measures the elevation of Palau’s lands and coasts, from Palau’s highest points down to 80 meters below sea level. Once compiled, the data will produce a map which is expected to help identify areas in Palau which are most at risk from disasters such as rising sea levels and typhoons.
The pilots and LiDAR specialists, who work at Fugro, a leading geological data company operating in countries around the globe, began the digital mapping survey last week, carrying out two four-hour flights a day. The project is expected to consist of a total of twenty flights, and will map out every island from Kayangel all the way down to Hatohobei.
The program is part of an Enhancing Disaster and Climate Resilience (EDCR) project, funded by the Government of Japan and put into effect by the United Nations Development Programme (UNDP). In addition to the LiDAR mapping survey, the project has included training workshops on disaster preparation for public and private sector employees in Palau, as well as the procurement of disaster-prevention equipment, including the automatic weather observation device which arrived in Palau last week.
The data collected during the flights will be used by the Office of the Palau Automated Land and Resource Information System (PALARIS) to generate maps needed for risk assessment along Palau’s coasts, and to plan for things such as flood management. PALARIS has also indicated that the digital map could be useful for planning development projects.
Mr. Tristan Haynes, the Project Manager at Fugro, explained how the technology works in a meeting at Palau International Airport on Monday afternoon with members of the Embassy of Japan, PALARIS, and UNDP, including Japanese Ambassador Akira Karasawa. Mr. Haynes said that the LiDAR system involved “a lot of engineering over many generations”.
In the tight cockpit of their Cessna aircraft, two pilots and a LiDAR specialist take off from Palau International Airport in the morning, flying below the clouds to avoid interference with the laser technology. The aircraft carries two LiDAR systems: the LADS HD+, a high-power and low-frequency sensor which measures elevations deep in the ocean, and the RIEGL VQ-820-G, a high-frequency and low-power sensor, used for capturing topographic points and shallow water, along with a digital camera which takes airborne imagery every two seconds. As the aircraft flies above land or water, the LiDAR system fires a green laser down below the plane, and a green receiver detects the reflections of the laser, calculating the time and distance of the pulse and measuring the elevation. The mapping continues for four hours, until the aircraft touches back down at Palau International around midday, the aircraft is refueled, and the team takes a 45-minute break, before taking off again for another four-hour mapping flight.
Mr. Haynes said that, ideally, the mapping could be finished in ten days of flights, although these days may be spaced out to account for bad weather and days which the pilots take to rest.
One of the benefits of the LiDAR technology is that it can measure the ground through obstructions such as trees and mangroves, which often cause trouble in elevation mapping, particularly along the coasts.
Ambassador Karasawa said that he is very confident that the LiDAR technology will help the people of Palau to better prepare for natural disasters.