|Titre :||Mapping wild fires in Prespa reedbeds. Use of BAIS2 Index and drone images : Short-communication technical report within the framework of LIFE Project “Prespa Waterbirds” LIFE15 NAT/GR/000936|
|Auteurs :||Loic Willm, Auteur ; F.-N Sakellarakis, Auteur ; Patrick Grillas, Auteur|
|Type de document :||Rapport|
|Editeur :||Arles (FRA) : Tour du Valat, 2021|
|Format :||21 + annex.|
|Mots-clés :||TdV ; Prespa ; Zone humide ; roselière ; Incendie ; Satellite ; lac|
|Mots-clés:||Remote sensing ; Sentinel-2 ; drone ; georeferencing ; mapping ; projective transformation ; reedbeds ; wildfires|
Remote sensing techniques can provide tools for mapping hazards in natural ecosystems, including wildfire events, targeting accurate mapping of distribution as well as post-event monitoring and recovery. Since 2019, whole lakeshore mapping of wildfire events and distribution in Lesser Prespa is implemented targeting solely the effects on reedbeds within the LIFE project Prespa Waterbirds. Based on previous work done in the area, fieldwork data coupled with sentinel-2 satellite images and remote sensing methodologies were used as a workflow pipeline in order to improve the delineation of wildfires in Prespa reedbeds. The implementation of the method used in 2019 (Burn Area Index for Sentinel-2 BAIS2) gave poor results in 2020. Therefore, a derivative of BAIS2, namely the deltaBAIS2, was created and is used since 2020. This derivative index is calculated as the difference before and after fire events of the value for each pixel of the BAIS2 index.
For 2021, at the same time as this analysis of satellite images, the use of oblique aerial images from drone missions to map burnt areas was tested, with a georeferencement tool from ArcMap. Both analysis (dBAIS2 and drone images) gave quite equivalent results and could be complementary. The satellite method is used to identify fire zones and map them while the drone method can be used to refine the delineation of burned areas.
A step-by-step methodological framework of drone photo analysis is also presented, to guide post-LIFE mapping of wildfire events.