Wind damage from serious storm events is believed to cost countries in the EU approximately 15 million Euros per year, and often substantially more. In the UK 2013-14 storm season, the Forestry Commission estimated that up to 30 million trees had been blown down, substantially more than the most recent major storms: 1987 (15 million), 1990 (3 million) and 1968 (8 million). Wind damage from serious storm events is believed to cost countries in the EU approximately 15 million Euros per year, and often substantially more. The quicker the damage is mapped after a storm, the faster the timber yield variations can be accounted for, and the more likely it is that useful timber can be retrieved from the fallen trees. As a result, identification of trees damaged by windblow during storm events in Scotland is a priority for the Forestry Commission and the Scottish Government.
Example outputs from the methodology for Caithness, Scotland. The areas outlined in red have been identified as forest loss.
Carbomap have developed a new tool for minimising loss to UK forestry based on a satellite measurements that identify where areas of woodland have been blown down during major storm events. The Scottish Government and the Forestry Commission were interested in a smarter, more efficient approach to forest monitoring that would reduce existing survey costs through faster recovery of windblown timber, and more accurate yield planning/management.
The European Space Agency Sentinel-1 satellites were used, taking advantage of the UK’s existing investment, because they uniquely provide freely available radar data across Scotland on a regular and frequent basis. Radar was preferred as it is not hindered by cloud cover, or available sunlight, which is of particular importance during periods of storm which typically happen in the winter months. The new methodology Carbomap developed in this project allowed areas of windblow damage to be identified, enabling appropriate and timely action to be taken by decision makers within the Scottish Government.
By cleverly combining the Sentinel-1 radar imagery with other auxiliary datasets Carbomap was able to provide a priority rating for each area of change. This priority rating combines a confidence score on the likelihood that an area of identified loss is an actual loss event. This information allows decision makers to determine whether further action is required efficiently and effectively.
Example of the methodology where in the left image the red areas outlined in black identify forest loss. While in the right image the colour scale is the priority score (with black areas of no forest loss).
No solution that solely uses Sentinel data can provide all the information that is required to enable retrieval of the timber from trees blown down in high winds. A complete operational system would complement the Sentinel-1 data with data collected from helicopters, UAVs, or by putting people into the field for visual inspection, as currently happens following catastrophic windblow events. However, this Sentinel-1 methodology provides a significant opportunity for cost reductions by targeting these existing efforts to the locations where more information is required, rather than undertaking blanket surveys post-storm event.