It is widely recognised that, whilst ground based data is needed to get a full picture, remote sensing from space is the best, and perhaps only credible, solution for monitoring the whole of worlds rainforests, and that radar satellites are the most efficient in doing so. This is unsurprising as in most rainforests it rains much of the time, and so for most of the time there is more than 80% cloud-cover.
Most satellites only spend a handful or two of minutes operating over the rainforests in any one orbit. With some orbits over ocean rather than forest, and with typically only 15 orbits per day, it may take days for a satellites orbit to return to pass over the same point near the equator where the rainforests are generally located. This means it can take months to build up a map of what is occurring below the clouds with optical systems and during that time much irrevocable damage can be done.
Mapping the rainforest
This is made harder if the maps are made in high enough resolution to detect ‘selective logging’ – where the loggers remove a few trees at a time, just as damaging in the long term, but making detection harder.
At these high resolutions satellites can only image areas a few 10’s of km wide on each pass further slowing the mapping process.
Loggers getting away with it
Except in special conditions, in some particular regions and/or seasons, the cloud conceals the activities of loggers from optical camera satellites for most of the time, but the radar can see through the cloud and at night, making it ten times as effective as the optical systems. When radar is then combined with large constellation size the situation changes – the COSMO-SkyMed constellation, for example, is capable of imaging the whole of the Indonesian rainforest at high resolution every few weeks! However, this is a huge area of images to inspect, even with automated techniques to highlight changes – this is where crowd sourcing can bring advantages.
For DeforestAction, Geodan developed the idea of using crowd sourcing to inspect forest images for logging activity and social networking for ‘peer review’ to verify changes on the satellite imagery, then providing links to people on the ground in country – often volunteers from NGO’s – to go and confirm logging is in progress. The results can then be provided to the local authorities so they can take action to stop illegal logging or prosecute those responsible. This approach was expected to appeal particularly to young people with their strong social networking and computing skills and vested interest in slowing global warming which will likely have so much more impact on their lives.
Earthwatchers is a web based systems already tested in Kalimantan in Indonesia where cloud cover is a huge problem. Telespazio’s e-geos, (sister company to Vega UK), provided free Cosmo ‘change detection’ composite imagery to carry out the trial of the system. Other free data from other sources, both optical and radar, was also used.
Users were each allocated their ‘own’ area of at risk rainforest to monitor in locations where ground teams were available for verification. The trial was very effective, with take up by a large social community, including large numbers of school children in Australia where it became a subject for class projects. Illegal activity was detected and prosecutions initiated.
The program certainly met the project’s declared mission ‘to empower young people to understand and act on the world’s greatest challenges’, at least for the duration of the trials.
The COSMO-SkyMed high resolution change detection imagery proved the most popular with the users, it being easier to interpret than simple radar imagery, highlighting logging activity more clearly, and with high resolution enabled selective logging and to be detected. However, operating with limited ‘free when available’ high resolution radar data and more extensive but low resolution free optical data showing mostly the top of clouds was frustrating.
The next step is to secure funding to carry out an ‘operational pilot’ with a guaranteed supply of high resolution radar data to show what can really be done with sufficient data availability, perhaps operating through the Climate and Environmental Monitoring from Space (CEMS) facility at the UK’s International Space Innovations Centre (ISIC). The idea would be to engage a much wider user community for the larger project – and that could mean you!
That’s what we would like to do with a ‘EarthWatchers’ app – would you be interested? Please let us know.