Lidar Will Be Used to Study Forests, Wetlands, Sea Coasts
08/31/2015
By Edwin L. Aguirre
Teams of researchers led by UMass Lowell are developing state-of-the-art “lidar” (light detection and ranging) technology to map and study the environment in unprecedented detail. Data gleaned from this investigation will help them better understand the impact not only of hurricanes, storm surges and tsunamis on coastal regions, but also global climate change.
Much like radar, which employs radio waves, lidar uses laser pulses to detect objects and precisely measure their distances to the source by illuminating the target and timing/analyzing its reflected light. Applications of this remote-sensing technique include 3-D mapping of forests and coastal wetlands, monitoring shoreline and sea-level changes and studying air flow and turbulence at wind-turbine farms.
The research efforts are being coordinated by the new UMass Experimental Center for Environmental Lidar (ExCEL), a multi-campus, interdisciplinary program sponsored by a $150,000 grant from the UMass President’s Science & Technology Initiatives Fund in 2014.
“Our vision is to create a center of innovation for lidar technology research and development, including associated software and data-processing algorithms that will position UMass as a national and international leader in the field of environmental lidar sensing, while providing technical resource and expertise to the public and private sectors in the Commonwealth, the Northeast region and beyond,” says UMass Lowell physics Prof. Supriya Chakrabarti, who directs ExCEL.
“The ExCEL team brings together existing expertise and resources from the Lowell, Amherst, Boston and Dartmouth campuses, while leveraging our collaborations with industry and government partners,” he says.
In July, ExCEL hosted a two-day lidar workshop at UMass Lowell that attracted more than 100 researchers, students and industry leaders. Attendees discussed the latest trends in lidar, shared their research and explored avenues of collaboration. One of the speakers was Gayla Evans of the U.S. Geological Survey’s Earth Research and Observation Center, who talked about using lidar to create a database of 3-D maps of the U.S. coast to study sea-level rise, storm-surge models and tsunami assessments, among other phenomena. Representatives from more than 25 universities, government agencies and businesses also presented their current research and participated in the event’s more than 15 sessions.
Measuring a Forest’s Biomass from the Ground
ExCEL’s goal is to use lidar to address three critical areas of environmental sensing, namely terrestrial ecology, oceanographic bathymetry (the study of underwater depths and terrain of continental shelves and ocean floors) and wind-energy generation.
Airplanes and helicopters are most commonly used in lidar scanning over broad areas, but the number of these flights is limited due to the high cost of instrument rental, aircraft time and processing. A team of researchers assembled by Chakrabarti and Asst. Prof. Timothy Cook in conjunction with UMass Boston and Boston University is helping to augment the data in the field using portable ground-based, high-resolution lidar systems the team has developed — the Dual Wavelength Echidna Lidar (DWEL) and the Canopy Biomass Lidar (CBL). These instruments are designed to directly measure, verify and/or monitor a forest’s carbon biomass above the ground in a way that is rapid, inexpensive and non-destructive to trees.
The DWEL, which was created with funding from the National Science Foundation (NSF), operates at wavelengths of 1064 and 1548 nanometers. It can separate the forest’s woody trunks and branches from the green, photosynthesizing leaves and provide 100-meter-wide hemispherical scans of the forest’s canopy structure. Recently, Australia’s Commonwealth Scientific and Industrial Research Organization, the country’s national science agency, funded the production of a second DWEL unit for use in the organization’s research programs.
The CBL, which operates at 905 nm, has been used to increase the area of the DWEL’s 3-D scans to a full hectare (2½ acres). Both the DWEL and CBL have been deployed in the field in Massachusetts, California and Australia. The CBL was also used in tropical rainforests and mangroves in Costa Rica and in New England salt marshes. The system has also shown its ability to capture rapid coastal changes in eastern Massachusetts, such as the erosion of bluffs by storm surges.
The Impact of Rising Sea Levels
Oceanographic bathymetric lidar is being applied to the study of sediment-transport processes associated with rising sea levels in response to climate change.
“Coastal erosion, both as a chronic issue associated with sea-level rise, as well as due to major events such as Hurricane Sandy in 2012 and the Blizzard of 2013, will have increasing impact on the Massachusetts economy, public and private properties and estuarine ecosystem as well as coastal tourism,” notes Chakrabarti.
A team led by UMass Dartmouth that includes Profs. Cook and Chakrabarti is developing ways to make rapid lidar measurements of the coast a tool in the maintenance, restoration and protection of the state’s shoreline and all other high-risk coastal regions.
Harnessing the Power of Wind
The aerodynamic characteristics and behavior of wind-turbine blades contribute directly to the cost, efficiency and reliability of generating power from wind. By using lidar to study the air flow and turbulence created in the wake of full-scale wind turbines, researchers hope to develop improved designs for turbine blades and commercial-scale wind farms.
Mechanical engineering Asst. Prof. David Willis and Cook are leveraging existing research efforts in wind energy at the Lowell and Amherst campuses to position ExCEL as a leading environmental sensing and impact-assessment resource in the field. The university recently received funding from the NSF to establish WindSTAR, the Industry/University Cooperative Research Center for Wind Energy, Science, Technology and Research, which aims to address pressing needs of industry. Furthermore, the university’s Wind Energy Research Group is leading the way in the low-cost, energy-efficient manufacturing — and recycling — of wind-turbine blades made from fiber-reinforced polymer composite.
“ExCEL will participate in the field-testing of these turbine blades,” says Chakrabarti.