Detection of trends in flood magnitude and frequency in Canada

Zadeh, Shabnam Mostofi; Burn, Donald H.; O’Brien, Nicole

doi:10.1016/j.ejrh.2020.100673

Cited by 22 publications

(16 citation statements)

References 43 publications

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“…However, these increases are not clearly observed in flood records of recent decades (Hirsch and Ryberg 2012, Kundzewicz et al 2014, Berghuijs et al 2017, Do et al 2017, Slater et al 2021, Zhang et al 2022. Across North America, flood trends appear spatially fragmented, whereby systematic causes of change remain largely unresolved (Cunderlik and Ouarda 2009, Archfield et al 2016, Slater and Villarini 2016, Hodgkins et al 2019, Dethier et al 2020, Zadeh et al 2020, and the Intergovernmental Panel on Climate Change (IPCC) emphasizes the low confidence in regional patterns of change (IPCC 2021). In addition to long-term trends, regionally, multi-year oscillations can exist with unusually many or few flood occurrences, referred to as flood-rich or flood-poor periods (Blöschl et al 2020, Lun et al 2020.…”

Section: Introductionmentioning

confidence: 99%

Groundwater shapes North American river floods

Berghuijs

Slater²

2023

Environ. Res. Lett.

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The importance of soil moisture in triggering river floods is increasingly recognized. However, soil moisture represents only a fraction of the water stored in the unsaturated zone. In contrast, groundwater from the deeper, saturated zone, may contribute a significant proportion of river flow, but its effects on flooding are poorly understood. Here we analyze hydroclimatic records of thousands of North American watersheds spanning 1981-2018 to show that baseflow (i.e., groundwater-sustained river flows) affects the magnitude of annual flooding at time scales from days to decades. Annual floods almost always arise through the co-occurrence of high precipitation (rainfall + snowmelt) and baseflow. Flood magnitudes are often more strongly related to variations in antecedent baseflow than antecedent soil moisture and short-term (≤3-day) extreme precipitation. In addition, multi-decadal trends in flood magnitude and decadal flood variations tend to better align with groundwater storage and baseflow trends than with changing precipitation extremes and soil moisture. This reveals the importance of groundwater in shaping North American river floods and often decouples the spatial patterns of flood trends from those of shifting precipitation extremes and soil moisture.

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Section: Introductionmentioning

confidence: 99%

Groundwater shapes North American river floods

Berghuijs

Slater²

2023

Environ. Res. Lett.

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“…RHBN includes 782 stations that measures streamflow at unregulated tributaries over Canada, and therefore are particularly suitable to address climate change impacts on natural streamflow regime (Brimley et al, 1999;Harvey et al, 1999;Whitfield et al, 2012;Zadeh et al, 2020). Considering the available data for the period of 1903 to 2015, we searched for the largest subset of stations with longest continuous daily record during a common period with negligible missing data (i.e., less than a month in a typical year).…”

Section: Case Study and Datamentioning

confidence: 99%

A novel algorithmic framework for identifying changing streamflow regimes: Application to Canadian natural streams (1966–2010)

Zaerpour

Hatami

Sadri³

et al. 2020

Preprint

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Abstract. Climate change significantly affects natural streamflow regime. To assess alterations in streamflow regime, typically few streamflow characteristics are considered and their significant variations in time and space are taken as a notion of change. Although, this approach is informative, intuitively appealing and widely-implemented, (1) it cannot see simultaneous changes in multiple streamflow characteristics; (2) it does not utilize all the available information contained in a streamflow hydrograph; and (3) it cannot describe how and to what extent one streamflow regime evolves into other regime types. To address these gaps, we conceptualize streamflow regimes as intersecting spectrums that are formed by multiple streamflow characteristics. Accordingly, we recognize that changes in streamflow regime should be diagnosed through gradual, yet continuous changes in an ensemble of streamflow characteristics. To incorporate these key considerations, we propose a fuzzy clustering-based approach to classify the natural streamflow into a finite set of intersecting regime types. Accordingly, by analyzing how the degrees of membership to regime types change, we quantify monotonic shifts between regime types in time and space. Our proposed algorithm eliminates the subjectivity in quantifying shift between flow regimes, and can extract valuable knowledge stored in the shape and variability of annual streamflow hydrographs. We apply this approach to the natural streamflow data, obtained from 106 Canadian gauges, during the period of 1966 to 2010. We show that natural streamflow in Canada can be categorized into six regime types, with clear physical and geographical distinctions. Analyses of trends in membership values during the study period show that alterations in natural streamflow regime are vibrant and can be different within and between major Canadian drainage basins. We show that gradual changes in natural streamflow regimes in Canada can be attributed to simultaneous changes in a large number of streamflow characteristics, some of which have been previously unknown or not well-attended. Our study introduces a generic algorithmic framework for identifying changing streamflow regime at regional and global scales, and provides a fresh look at streamflow alterations in Canada, which can be seen as another line of evidence for the complex and multifaceted impacts of climate change on streamflow regime, particularly in cold regions.

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“…The threat of natural disasters has always been present, but since the 1960s, the frequency of natural disasters related to hydrometeorological hazards has increased nearly three times to reach the level observed today [ 2 , 3 , 4 ]. In the province of Quebec (Canada), the severity and recurrence of floods seem to have increased in recent years over its eastern and maritime regions [ 5 ]. Climate change results in more frequent and intense precipitation, which, when combined with the rapid melting of the snow cover, can increase the risk of flooding [ 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Respiratory and Otolaryngology Symptoms Following the 2019 Spring Floods in Quebec

Landaverde

Généreux

Maltais

et al. 2022

IJERPH

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Background: Although floods may have important respiratory health impacts, few studies have examined this issue. This study aims to document the long-term impacts of the spring floods of 2019 in Quebec by (1) describing the population affected by the floods; (2) assessing the impacts on the respiratory system according to levels of exposure; and (3) determining the association between stressors and respiratory health. Methods: A population health survey was carried out across the six most affected regions 8–10 months post-floods. Data were collected on self-reported otolaryngology (ENT) and respiratory symptoms, along with primary and secondary stressors. Three levels of exposure were examined: flooded, disrupted and unaffected. Results: One in ten respondents declared being flooded and 31.4% being disrupted by the floods. Flooded and disrupted participants reported significantly more ENT symptoms (adjusted odds ratio (aOR): 3.18; 95% CI: 2.45–4.14; aOR: 1.76; 95% CI: 1.45–2.14) and respiratory symptoms (aOR: 3.41; 95% CI: 2.45–4.75; aOR: 1.45; 95% CI: 1.10–1.91) than the unaffected participants. All primary stressors and certain secondary stressors assessed were significantly associated with both ENT and respiratory symptoms, but no “dose–response” gradient could be observed. Conclusion: This study highlights the long-term adverse effects of flood exposure on respiratory health.

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Detection of trends in flood magnitude and frequency in Canada

Cited by 22 publications

References 43 publications

Groundwater shapes North American river floods

Groundwater shapes North American river floods

A novel algorithmic framework for identifying changing streamflow regimes: Application to Canadian natural streams (1966–2010)

Respiratory and Otolaryngology Symptoms Following the 2019 Spring Floods in Quebec

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