The big picture
LiDAR (Light Detection and Ranging) is a remote sensing technology that measures distance using airborne lasers. It creates highly accurate three-dimensional representations of surface features and objects, such as vegetation or buildings, by measuring the time it takes for laser light reflected from the ground to return.
Aside from scientific enquiry, another appeal of this technology lies in its visual and artistic aspects. The images are captivating, and because the information has never been presented in this way before, they give us fresh insights which emerge at the confluence of science and art.
An aircraft or unmanned drone is usually used for LiDAR scans collecting up to 100,000 laser measurements per second. The data from scans can be used to create a set of points that show the 3D shape of the scanned objects, commonly referred to as a ‘point cloud’. Each point represents a specific location on the earth’s surface, in three dimensions: the conventional flat two-dimensional map position, plus the corresponding elevation or height. Geospatial information from satellites can be added to augment coverage.
Passing over any terrain taking LiDAR measurements achieves in minutes what could take hundreds of hours of manual surveying. Because it is so accurate and quick to collect, it can show changes over time, revealing transformations that might otherwise be missed. This is absolutely the case for the Rivers Alde and Ore, where change is constantly occurring, whether intertidal, seasonal, or across much longer time periods.
What can the measurements be used for?
LiDAR is widely used in planning and environmental management to support spatial decision-making and improve understanding of real-world features and phenomena.
Common applications include land use classification, environmental impact assessments and natural resource and climate change investigation. Data on sensitive habitats, water bodies or endangered species can be overlayed onto accurate and highly detailed surface elevation models. This can reveal existing and potential effects of flooding, river flow and erosion (of rivers and coasts), and the impact of human activity, including modifications to the built environment. LiDAR passes can assess forest inventory, tree canopy density, and monitor changes in marshland. LiDAR can even penetrate vegetation to the ground below by working out the difference between the first and last return of each emitted laser pulse.
Insights into river dynamics and patterns
LiDAR aerial imagery is well suited to the unique characteristics and challenges associated with river systems. River network analysis, including elevation, flow direction, sediment transport, erosion, drainage patterns, and watershed delineation can help us understand river connectivity and the full range of hydrological processes. It can also be used to map floodplains, a topic of growing importance in the south and east of England, where rising demand for housing has pushed construction into riskier lower-lying land.
Revealing the invisible through time
In Suffolk, LiDAR offers profound insights into the unique environment of the Alde, Ore, and Butley rivers and their surroundings. Because the rivers wind dramatically there is high potential for bank erosion and changes in their courses. The technology can also model and assess flood risks and potential effects according to different tidal scenarios. This allows for specifically targeted environmental interventions to reduce these impacts and to plan emergency response strategies.
Planning for climate change resilience
Perhaps most critically, LiDAR can assist climate change adaptation strategies for the estuary. By modelling potential impacts, such as sea-level rise and the consequences of increased rainfall intensity, it can help organisations like Lead Local Flood Authorities to identify vulnerable areas, and plan resilient infrastructure. Planners can then mitigate the effects of climate change on the river system and ensure the conservation and enhancement of the rivers’ natural and cultural resources for present and future generations.
In addition to their practical use, LiDAR images can be beautiful and interesting. New creations can be seen at LidarMaps.org