Abstract
Abstract. Floodplain wetlands play a key role in hydrological and biogeochemical cycles and comprise a large part of the world's biodiversity and resources. The exploitation of remote sensing data can substantially contribute to monitoring procedures at broad ecological scales. In 2020, the Lower Paraná River floodplain (also known as Paraná River Delta, Argentina) suffered from a severe drought, and extended areas were burned. To monitor the wildfire situation, satellite products provided by FIRMS-NASA were used. These thermal hotspots – associated with active fires – can be downloaded as zipped spatial objects (point shapefiles) and include recent and archive records from VIRRS and MODIS thermal infrared sensors. The main aim was to handle these data, analyze the number of hotspots during 2020, and compare the disaster with previous years' situation. Using a reproducible workflow was crucial to ingest the zip files and repeat the same series of plots and analyses when necessary. Obtaining updated reports allowed me to quickly respond to peers, technicians, and journalists about the evolving fire situation. A total of 39,821 VIIRS S-NPP thermal hotspots were detected, with August (winter) accounting for 39.8% of the whole year’s hotspots. MODIS hotspots have lower spatial resolution than VIIRS, so the cumulative MODIS hotspots recorded during 2020 were 8,673, the highest number of hotspots of the last 11 years. Scripts were written in R language and are shared under a CC BY 4.0 license. QGIS was also used to generate a high-quality animation. The workflow can be used in other study areas.
Highlights
Wetland ecosystems play a key role in hydrological and biogeochemical cycles and comprise a large part of the world's biodiversity and resources (Keddy, 2010)
Ground-truth data are not shown in this article, the author has confirmed active fire locations with: a) information of local population and fire brigade members; b) georeferenced photographs obtained by López Brach during a flight over onfire areas in June 2020 and gently shared to the author; c) postfire visits done by the author in March 2021: charcoal and burned soils and vegetation were observed in sites that had been previously identified with thermal hotspot records
This work is an ecological application of spatial analyses conducted with open-source software (R, QGIS)
Summary
Wetland ecosystems play a key role in hydrological and biogeochemical cycles and comprise a large part of the world's biodiversity and resources (Keddy, 2010). South America is the continent with the largest surface covered by wetlands, with the greatest extension being covered by fluvial wetlands associated with the Amazonas, the Orinoco and the Paraguay-Paraná rivers (Junk et al, 2013) These ecosystems' dynamics are mainly controlled by flood pulses (Junk et al, 1989), which determine fluxes of materials and organisms between the river and the floodplain, influence ecological processes, and affect biodiversity patterns (Gayol et al, 2019; Marchetti and Aceñolaza, 2012; Morandeira and Kandus, 2017). Due to the large extension of fluvial wetlands and their restricted accessibility, the exploitation of remote sensing data can substantially contribute to monitoring procedures at broad ecological scales (Kandus et al, 2018; Tiner et al, 2015) This is especially true during extreme events that limit accessibility even more than usual, such as floods, droughts (hindering navigation), or wildfires. Lockdown due to the epidemiological situation was an extra factor limiting accessibility
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