Drones and advanced cameras are powerful tools that help us understand our aquatic environments in ways that were previously impossible
With groundbreaking sensor technology, drones can now scan life underwater – from the air. 3D environmental monitoring is the future, according to NIVA researchers.
Published: 12.09.2024
Written by: Gunnar Omsted
Key researchers: Hege Gundersen, Kasper Hancke
In a time where climate change and human activity increasingly impact our ecosystems, environmental monitoring has never been more important. At NIVA, we are continuously seeking new and innovative methods to improve our work, and right now, drone-based sensor technology is one of the most exciting developments.
– Norway is already at the forefront. And the latest technology we are now testing is simply revolutionary. We are using laser technology from drones, which allows 3D scanning both above and below water, with a level of detail far higher than before. This gives us a unique opportunity to understand our aquatic environments in a whole new way, says senior researcher Kasper Hancke at NIVA.
Despite the expensive equipment, significant cost savings can be achieved in environmental management.
– Compared to traditional methods, we will soon be able to monitor much larger areas with much higher detail and, not least, much faster, says the NIVA researcher.
Fast and efficient
It is already well-known that drones equipped with so-called RGB and multispectral cameras can scan large areas in a short amount of time. They provide us with detailed maps and data about water quality, pollution, and the distribution of plant and animal life. For instance, drones can detect harmful algae blooms that may be dangerous to both humans and animals – contributing to faster and more targeted interventions.
For several years, NIVA researchers, including through SeaBee projects, have monitored everything from water quality to life in and around water, including the sea, coast, rivers, and lakes. The data is used to understand how ecosystems change over time.
– The latest development is that we are not only mapping distribution – like a two-dimensional image – but now we can also map and scan habitats in three dimensions, both above and below water, says Hancke.
How? With the help of technology you might already have in your pocket.
This is the future of environmental monitoring, where technology and research go hand in hand.
Hege Gundersen
Using ‘iPhone technology’
Although it is not as advanced, some of the same technology is found in newer iPhone models as in NIVA’s cutting-edge drones. In a so-called LiDAR sensor on the phone, infrared laser pulses are emitted that spread across the surroundings. When these pulses hit objects, they are reflected back to the sensor. By measuring how long it takes for the pulse to return, the iPhone can calculate the distance to various objects. This can provide a three-dimensional map of the surroundings in real-time.
But let’s go back to the air and the NIVA drones. Even though the distances are larger, the principle is the same as the technology in iPhones. By calculating the time it takes for laser pulses to return to the drone from the ground or seabed, the LiDAR sensor on the drone can quickly and accurately create a 3D/depth map of the surroundings.
Here we see a three-dimensional terrain model of a coastal area near Larvik. The colours show height differences, where red is the highest (maximum height = 30 m). The model is made with red LiDAR, which causes the water surface in the middle of the model to appear flat because red LiDAR cannot penetrate water. With green LiDAR, you also get information about the seabed (bathymetry) and vegetation under the water.
A bathy-topographic model is a 3D representation showing both the seabed (bathymetry) and terrain (topography). The model is based on green LiDAR data and is displayed as a “point cloud,” meaning a large number of data points precisely placed in a 3D grid. The resolution is 8-12 points per square metre, with an accuracy of about 3 cm.
For environmental monitoring, we also distinguish between green and red LiDAR. Hancke explains that for land-based mapping or vegetation analyses, red LiDAR is usually the best choice. This technology has been available in recent years. For underwater mapping, however, green LiDAR is necessary.
– Green light has the ability to penetrate the water surface and down through the water. This technology has only recently become available for drones and opens up entirely new areas of application, such as mapping kelp, seaweed, and eelgrass in coastal zones. We can also use it for mapping river channels and lakes, as well as underwater vegetation, says Hancke.
– It is now possible to map the seabed and species and habitats in shallow marine areas from drones, explains the NIVA researcher.
Three dimensions better than two
By including a third dimension, the 3D images from the LiDAR provide a much better understanding of the habitat’s volume and spatial distribution.
– Take, for example, eelgrass beds, which are extremely important for marine biodiversity. The area coverage of a meadow only gives part of the answer to how much of this habitat exists. It is only when the height of the eelgrass is considered that we get a measure of the amount of eelgrass in the meadow, explains senior researcher Hege Gundersen at NIVA.
This is important knowledge for calculating how much carbon is stored in the eelgrass biomass and how much carbon can potentially be sequestered in the seabed long-term. This allows researchers to assess the value of eelgrass meadows as carbon sinks and calculate how much CO2 eelgrass meadows absorb from the atmosphere.
This gives us a unique opportunity to understand our aquatic environments in a whole new way.
Kasper Hancke
Technology + research = success
After the drones have finished their “buzzing” and the enormous amount of collected data is analysed, machine learning plays a crucial role.
– Advanced algorithms make it possible to identify patterns and anomalies that may indicate environmental problems. Examples include a sudden reduction in the distribution of an important habitat or the spread of unwanted species, says Gundersen.
By using machine learning, researchers can also predict future trends and potential threats, enabling preventive measures to be taken before problems escalate.
– Understanding and monitoring our aquatic environments is crucial for preserving them. With drones, new sensor technology, and machine learning, we have powerful tools that help us get to know our aquatic environments in ways that were previously impossible. This is the future of environmental monitoring, where technology and research work hand in hand towards a sustainable future, says Gundersen.
Original article posted by NIVA
This article has been translated from Norwegian