Drones and environmental mapping

Unmanned Aerial Vehicles (UAVs) or ‘drones’ are a rapidly evolving area of technology with many potential applications from intelligence gathering to delivering Amazon orders.   However, they also have clear environmental applications and here Duncan Blake, SNH’s lead analyst on remote sensing advice, explains how they can help in monitoring our natural heritage.

UAVs offer several advantages over traditional remote sensing platforms (aircraft and satellites). They can be deployed rapidly and regularly which allows repeat surveys of dynamic environments at low cost. They can fly lower so are less affected by cloud (in fact on cloudy days shadows are less of a problem) and can collect much higher resolution imagery.

They also have a much lower carbon footprint than a larger aircraft. On the other hand strong winds and rain can be a problem and Civil Aviation Authority regulations limit the use of UAVs to within 500 metres of the operator.

The products they can provide include traditional aerial photography, infrared aerial photography which is invaluable for vegetation mapping and monitoring and detailed Digital Surface Models (DSMs) derived from overlapping aerial images.

SNH is investigating their potential in a number of areas by assessing images being provided by EagleiSystems in Dundee.

The first of these is coastal change assessment. Some parts of the Scottish coastline are very dynamic, especially with the growing impact of climate change, so predicting how they may change is crucial for planning protection or mitigation measures.

One such example is the dunes north of St. Andrews, which have been managed by a local partnership. Episodic erosion is being managed by beach feeding, where by sand is moved from plentiful areas to areas of sediment scarcity. Repeated topographic surveying is essential to inform where and when to take sand.

A sample image of part of the area is shown below. In this case each individual pixel is less than 1cm in size.

The second image has an overlaid DSM which has been created from the overlapping aerial imagery. This will allow us to plot the location of the current Mean High Water Spring line. Monitoring this over time lets us see the direction and rate of coastal erosion or accretion.

This winter SNH hopes to trial whether the technology can also provide efficiencies in monitoring deer populations. These surveys are better carried out in the winter months to minimise the effects of forest cover and because deer can be more readily isolated against a snow backdrop.




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