Hydrology and stream water quality of fire-prone watersheds

Pacheco, Fernando António Leal; Fernandes, Luís Filipe Sanches

doi:10.1016/j.coesh.2021.100243

Cited by 7 publications

(3 citation statements)

References 51 publications

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“…While wildfires have been a common occurrence over millennia in such Mediterranean ecoregions (Carrión et al., 2003; Naveh, 1975; Stavros et al., 2014; Verkaik et al., 2013), and are an important part of the natural wildfire‐adapted landscape (Stephens et al., 2020), the unprecedented nature of recent wildfires may lead to fundamental changes in watershed hydrology (Ball et al., 2021; Goss et al., 2020). Numerous reviews have identified the impacts of wildfire on watershed hydrology (Mishra et al., 2020; Pacheco & Sanches Fernandes, 2021) including increased runoff, debris flows, and water yields (Hallema et al., 2017, 2019; Wagenbrenner et al., 2021; Wine et al., 2018), and decreased groundwater infiltration from wildfire‐induced hydrophobicity and ash storage (Caltabellotta et al., 2022; Ebel et al., 2012). In contrast, other studies have observed confounding effects, including decreases in post‐wildfire peak flows and runoff coefficients despite greater rainfall (Balocchi et al., 2020; Beyene et al., 2021), reductions in streamflow due to re‐sprouting forests and drought (Nolan et al., 2015), and decreased baseflow recession rates attributed to greater evapotranspiration (Bart & Tague, 2017; Maina & Siirila‐Woodburn, 2019).…”

Section: Introductionmentioning

confidence: 99%

Prolonged Drought in a Northern California Coastal Region Suppresses Wildfire Impacts on Hydrology

Underwood

Murphy

et al. 2023

Water Resources Research

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Wildfires naturally occur in many landscapes, however they are undergoing rapid regime shifts. Despite the emphasis in the literature on the most severe hydrological responses to wildfire, there remains a knowledge gap on the thresholds of wildfire (i.e., burned area/drainage area ratio, BAR) required to initiate hydrological responses. We investigated hydrological changes in the Russian River Watershed (RRW) in California, a coastal, Mediterranean, drought‐prone, wildfire‐adapted ecosystem, following ten wildfires that burned 30% of the watershed. Our findings suggest that sub‐watersheds of the RRW have not burned beyond an intrinsic, unknown, threshold required to initiate change. Using paired watersheds, we examined spatiotemporal patterns of pre‐and‐post wildfire hydrology with a rainfall‐runoff hydrological model. Even though these successive wildfires burned 1%–50% of each sub‐watershed (1%–30% at moderate/high severity), we found little evidence of wildfire‐related shifts in hydrology. As a function of BAR, wildfire imposed limited effects on runoff ratios (runoff/precipitation) and runoff residuals (observations—model simulations). Our findings that post‐wildfire runoff enhancements asymptote beyond 30% burn indicate that when a watershed is burned beyond a certain threshold, the magnitude of the hydrologic response no longer increases. Drought and storm conditions explained much of the variability observed in streamflow, whereas wildfire explained only moderate variability in streamflow even when wildfire accounted for >45% BAR. While the BAR in the RRW was sufficiently beyond previously reported minimum disturbance thresholds (>20% burned forest), the lack of hydrological response is attributed to buffering effects of wildfire adaptation and drought factors that are unique to Mediterranean ecoregions.

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Section: Introductionmentioning

confidence: 99%

Prolonged Drought in a Northern California Coastal Region Suppresses Wildfire Impacts on Hydrology

Underwood

Murphy

et al. 2023

Water Resources Research

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“…Murphy et al (2006a, b) reported that fires (combustion and volatilization) can cause a significant reduction of N (92%, NH 4 -N increase from combustion and subsequent NO 3 -N increases from nitrification) and P (76%; particulate P bioavailable) stored in forest floor (organic material), with minor decline (N 31%-51%) recorded under lower fire intensity. The magnitude and duration of hydrological and geomorphological activity following wildfires depends on the complex interplay of factors including site (e.g., catchment size) and fire characteristics (e.g., burned area severity and extent) as well as post-fire rainfall patterns (Pacheco and Fernandes, 2021). Changes in post-wildfire runoff and erosion are most severe during high-intensity rainfall (Moody et al, 2013) especially when occurring after fire events, since vegetation has little time to recover from fire.…”

Section: Introductionmentioning

confidence: 99%

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

Pinardi

Stroppiana²,

Caroni³

et al. 2023

Front. Remote Sens.

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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.

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“…Many of these extreme forest fires occur in areas under some environmental protection status [18][19][20], in which the lack of fuel management exacerbates the problem. These disturbances not only entail serious consequences to ecosystems, including severe vegetation and soil damage [21,22] and water system disturbance [23,24], but also to human life and assets [25][26][27]. In the Mediterranean Basin, where the WUI area has increased [28], extreme forest fires, such as those that occurred in Portugal in 2017, in Greece in 2018 or in Spain in 2021 and 2022, have seriously endangered inhabitants and caused unusual fatalities [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Drivers and Trends in the Size and Severity of Forest Fires Endangering WUI Areas: A Regional Case Study

Rodriguez-Jimenez,

Fernandes,

Fernández-Guisuraga

et al. 2023

Forests

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This study explored, for the first time, the drivers shaping large fire size and high severity of forest fires classified as level-2 in Spain, which pose a great danger to the wildland–urban interface. Specifically, we examined how bottom-up (fuel type and topography) and top-down (fire weather) controls shaped level-2 fire behavior through a Random Forest classifier at the regional scale in Galicia (NW Spain). We selected for this purpose 93 level-2 forest fires. The accuracy of the RF fire size and severity classifications was remarkably high (>80%). Fire weather overwhelmed bottom-up controls in controlling the fire size of level-2 forest fires. The likelihood of large level-2 forest fires increased sharply with the fire weather index, but plateaued at values above 40. Fire size strongly responded to minimum relative humidity at values below 30%. The most important variables explaining fire severity in level-2 forest fires were the same as in the fire size, as well as the pre-fire shrubland fraction. The high-fire-severity likelihood of level-2 forest fires increased exponentially for shrubland fractions in the landscape above 50%. Our results suggest that level-2 forest fires will pose an increasing danger to people and their property under predicted scenarios of extreme weather conditions.

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Hydrology and stream water quality of fire-prone watersheds

Cited by 7 publications

References 51 publications

Prolonged Drought in a Northern California Coastal Region Suppresses Wildfire Impacts on Hydrology

Prolonged Drought in a Northern California Coastal Region Suppresses Wildfire Impacts on Hydrology

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

Drivers and Trends in the Size and Severity of Forest Fires Endangering WUI Areas: A Regional Case Study

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