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Description
In 2019, an unprecedented number of wildfires damage and disruption throughout the world, including the Amazon River Basin (ARB), where an unusually high number of fires were observed along the Rio Branco, which is connected to the Atlantic Ocean via the Amazon River. While many coastal waterways are downstream of areas susceptible to wildfires, the vulnerability of coastal areas to terrestrial watershed disturbances remains understudied. Runoff from burned areas transport ash and sediments, increasing contaminant loading of receiving waters. This research is one of the first to evaluate spatial and temporal dynamics of terrestrial processes after the 2019 fires in the eastern ARB. This work characterized the extent and magnitude of wildfires and compared pre- and post-fire terrestrial conditions using satellite-based products and evaluated post-fire water turbidity and emissions for 2019. Differenced normalized burn ratio (dNBR), Enhanced Vegetation Index (EVI), precipitation, soil moisture, surface runoff, and evapotranspiration (ET) were used to compare pre- and post-fire vegetation and watershed conditions. Streamflow and turbidity data were obtained for two gauge stations in the Rio Branco and Amazon River for water year (WY) 2016 to WY2020. Global Forest Watch and Global Wildfire Information System (GWIS) were utilized to characterize fires and estimate greenhouse gas emissions, respectively. Although WY2019 was not a drought year in Roraima, the amount and severity of its fires were comparable to drought years. In WY2019, 702,122 hectares of vegetation burned, which was more than triple the historical average area burned in Roraima. Increases in fires were linked with deforestation and uncontrollable fires, which contributed to a nearly 275% increase in greenhouse gas emissions compared to preceding years. Higher turbidity events were due to decreased vegetation biomass, proxied by EVI, and increased precipitation after fire, consistent with greater soil moisture and surface runoff. Furthermore, ET was lowest during the dryer seasons, correlating with deforestation and fire. This research presents implications for understanding critical changes in water quality and shifts in terrestrial processes near coastal environments after fire events to be applied not only to the ARB, but also globally.
