The damage done to Spain’s Guadalajara province byJuly’s fierce forest fire has been measured from space by Envisat.
The four-day blaze began on 16 July, when a barbecue in pine woodland went outof control, spread by strong winds across a very dry landscape. Eleven volunteerfirefighters died tackling the blaze, which at its height threatened to engulfthe nearby villages of Selas and Ablanque. Firefighters succeeded in creating afire-break to stop its spread, backed up by water-bombing aircraft.
As the Spanish authorities assess the fire’s aftermath, a rapid damageestimate has been performed using Envisat’s Medium Resolution ImagingSpectrometer (MERIS) instrument.
MERIS image acquired 24 July
A 24 July MERIS Full Resolution mode image with aspatial resolution of 300 metres was processed to reveal burned areas by a teamled by Dr. Federico González-Alonso, head of the Madrid-based Laboratorio deTeledetección (Remote-sensing Laboratory) of the Instituto Nacional deInvestigación y Tecnología Agraria y Alimentaria (National Institute forAgriculture, Food Research and Technology or INIA).
“MERIS measures the solar radiation reflected by the Earth in 15selectable spectral bands in the visible and near infra-red,” explainedGonzález-Alonso. “We utilised bands that were particularly sensitive tovegetation, then performed an automatic matched filtering analysis on thestacked bands to designate ‘endmembers’ – spectrally pure areas that could bevisually classified as very burnt.
“The file obtained was reclassified by modifying the histogram orgraphical bar used, so pixels with values over 0.3 were considered burnt. Theresulting perimeter gives us a burnt area estimate of 11 313 hectares.”This figure compares well to forest fire burnt area estimates from other sourcesof 12 000 hectares.
Burned-area perimeter detected in MERIS image
“The results of our completed study will be sent tothe Spanish Ministry of Environment for economic, social and ecological damageassessment,” González-Alonso added. “Our team has been studying theuse of MERIS data for fire-damage assessment – the obtaining of images from ESAin near-real time via the internet being an essential point in this kind ofapplication.”
“The results achieved so far show that estimates can be extremely usefulnot only in establishing the scale of the damage but also for the subsequentforest renewal projects and for subsidy management.”
The team is also participating in ESA’s Dragon Programme of cooperation withChinese researchers, using MERIS Full Resolution imagery to map forest firesacross China.
Guadalajara forest fire devastation
González-Alonso explained that MERIS’s visible andinfra-red multispectral imaging capability combined with a better spatialresolution than comparable satellite sensors make it especially useful forproviding fire-damage information.
MERIS’s capability is being employed in a variety of different projects,including as part of GLOBCARBON, a project to better characterise changes in theamount of land-based carbon on a global basis across ten years from1997.
Monitoring the location, duration and affected area of forest fires is animportant part of GLOBCARBON, since blazes are a major way for carbon to bereleased from land-based ‘sinks’ into the atmosphere. The project, part of ESA’sData User Element, should improve scientific understanding of the carbon cycleand improve climate change modelling.
MERIS is also being utilised in combination with other satellite sensors forthe Risk-EOS initiative, which is rolling out a series of operational servicesfor fire and flood risk management, with burn scar mapping initially beingoffered within a total area of 180 000 square kilometres across two parts ofEurope: Spain’s Castilla y Leon Region and the Éntente area of southern France.
ESA’s Envisat environmental satellite
Risk-EOS is taking place as part of the GMES ServicesElement (GSE), a suite of Earth Observation services being developed as part ofthe Global Monitoring for Environment and Security (GMES) joint endeavourbetween ESA and the European Commission, aimed at merging ground- andspace-based information sources to develop a comprehensive planetary monitoringcapability in support of Europe’s environment and security goals.
A follow-on to MERIS is planned as payload for the GMES-1 spacecraft,intended to support operational GMES services into the next decade.