Assessing the impact of wildfires on water quality using satellite remote sensing: the Lake Baikal case study

Abstract

Lakes have been observed as sentinels of climate change. In the last decades, global warming and increasing aridity has led to an increase in both the number and severity of wildfires. This has a negative impact on lake catchments by reducing forest cover and triggering cascading effects in freshwater ecosystems. In this work we used satellite remote sensing to analyse potential fire effects on lake water quality of Lake Baikal (Russia), considering the role of runoff and sediment transport, a less studied pathway compared to fire emissions transport. The main objectives of this study were to analyse time series and investigate relationships among fires (i.e., burned area), meteo-climatic parameters and water quality variables (chlorophyll-a, turbidity) for the period 2003–2020. Because Lake Baikal is oligotrophic, we expected detectable changes in water quality variables at selected areas near the three mains tributaries (Upper Angara, Barguzin, Selenga) due to river transport of fire-derived burned material and nutrients. Time series analysis showed seasonal (from April to June) and inter-annual fire occurrence, precipitation patterns (high intensity in summer) and no significant temporal changes for water quality variables during the studied periods. The most severe wildfires occurred in 2003 with the highest burned area detected (36,767 km2). The three lake sub-basins investigated have shown to respond differently according to their morphology, land cover types and meteo-climatic conditions, indicating their importance in determining the response of water variables to the impact of fires. Overall, our finding suggests that Lake Baikal shows resilience in the medium-long term to potential effects of fires and climate change in the region.

Investigating the Impact of Wildfires on Lake Water Quality Using Earth Observation Satellites

“…Shallow lakes typically have higher production per unit area when compared to deep lakes with similar phosphorus and total dissolved matter concentrations, as a result of faster nutrient cycling and better mixing and lighting conditions [58,59]. For fire-burned materials and soil-released nutrients transported via a terrestrial pathway, especially by increased runoff in a lake catchment after precipitation events, the morphology of the final receptor lake is therefore a determinant for the internal process dynamics and ultimately for lake primary production [8]. It is long acknowledged that lake basin morphology plays a key role in modulating lake water quality, and in particular depth has important consequences on mixing regimes, light, and nutrient availability, affecting biological production and processes within a lake.…”

“…Wildfires can have an impact on river and lake water quality by altering the physical, chemical, and biological characteristics of soils and aquatic ecosystems [5]. Much research has focused on the consequences of wildfires on terrestrial ecosystems and air quality, while until recently the effects of wildfires on water quality have been relatively overlooked [6][7][8], while the majority of research concerning the aquatic impacts of wildfires is based on streams and rivers rather than lakes.…”