Project Background / Overview
The aim of this project was to establish an operational monitoring programme to track the environmental impacts of land management in the English uplands. Efforts were focussed on two aspects: confirmation of the feasibility of using radar imagery to detect moorland burns from SAR data (specifically from Sentinel-1), and establishing the workflows required to create an operational system. As part of this:
- A comparison of radar processing software and techniques was made,
- Time series analysis of ERS-2 data was conducted to act as a proxy for Sentinel-1, and
- Development of practical, robust and consistent analytical methods.
- Sentinel-1 SAR data can be readily prepared and processed for integration into Earth observation analysis systems
- C-band VV SAR proved capable of detecting burns >1ha in area and >40m wide within mature heather
It was found that a time-series of 10 or more SAR images was required to achieve the best combination of spatial and radiometric resolution.
Finally, Sentinel-1 SAR data can be readily prepared and processed for integration into Earth observation analysis systems (as a proxy), whilst Sentinel-2 optical imagery can be used to provide baseline maps of annual burn extent.
Costs and Benefits
Whilst no cost benefit analysis is contained within the final report there are ‘value for money’ considerations:
- The approaches described (in the report) would require a skilled analyst and interpreter in both SAR and optical remote sensing.
- A high performance work station or server is recommended, especially when automatic processing of multi-image time series is planned.
- The main costs in utilising SAR is the requirement of processing a time-series of 10+ images to gain the best combination of spatial and radiometric resolution. While this pre-processing can be automated, it will require an initial overhead (hardware and software) to set up and run. The other main cost would be the skilled analyst needed to conduct the burn-mapping.
- Augmenting a SAR system with optical analysis, using pre- and post- burn season imagery from, for example, Sentinel-2 or Rapideye, would allow a complete national map of the majority of burns to be delivered.
- Given the suitability of SAR for automated and standardised pre-processing, there is an opportunity to offer SAR processing as a common service across Natural England/DEFRA.
This project successfully demonstrated that it is possible to use SAR systems and methods to monitor the burning of heather in the uplands of England. The next steps are to explore the use of different systems, such as NovaSAR-S, to see if it is better suited to the application and can produce more accurate or more cost-effective results.