Flood events and flood risk assessment in relation to climate and land-use changes: Saint-François River, southern Québec, Canada

Abstract

In the current context of climatic variability, it is important to quantify the impact on the environment. This study deals with an analysis of climatic data and land-use changes in terms of the impacts on flood recurrence based on multisource data. The study area covers the mouth of the Saint-François River (southern Québec, Canada), where spring floods and ice jams are a recurring problem. The flood frequency analysis shows an increase in flooding over recent decades, attributable to an increase in winter temperatures that has the effect of causing ice jams earlier in the year. Regarding land-use changes, a small decrease in agricultural surface areas is observed, from 53% to 39%, along with increases in forest and urban surface areas from 27% to 38% (forest) and 3% to 5% (urban) between 1928 and 2005. In a context of continuing climate warming, more pronounced inter-annual variations are to be expected along with a higher incidence of flooding.Key words flood frequency; ice jams; climatic variability; land-use changes; southern Québec; Canada Inondation et évaluation du risque d'inondation en lien avec les changements climatiques et d'occupation des solsRésumé Dans le contexte actuel des changements climatiques, il devient nécessaire de quantifier leurs effets sur l'environnement. Cette étude porte sur l'analyse des impacts climatiques et anthropiques sur la récurrence des inondations à partir de données multisources. La région d'étude couvre l'embouchure de la rivière SaintFrançois (sud du Québec, Canada), où les inondations printanières et les embâcles demeurent toujours un problème récurrent. Il ressort de l'analyse fréquentielle des inondations une augmentation depuis les dernières décennies qui est attribuable à un réchauffement des températures hivernales lesquelles ont pour effet de provoquer des embâcles plus hâtives dans l'année. Au niveau des changements d'occupation du sol, on note une diminution des surfaces agricoles aux dépens de l'extension des surfaces forestières et urbaines avec des valeurs respectives de 27% à 38% (forêt) et de 3% à 5% (urbain) entre 1928 et 2005. Dans la perspective où le réchauffement du climat se poursuivrait, on peut s'attendre à des variations interannuelles plus marquées et une plus forte incidence des risques d'inondation.

Freedom space for rivers: An economically viable river management concept in a changing climate

“…In Quebec as elsewhere, climate change will likely result in increased variability in both liquid and solid discharges, and thus in river dynamics and services (Lane et al, 2007;Ouranos, 2010;Verhaar et al, 2011;CEHQ, 2012). The flow regime, for example, will be affected by more frequent floods in winter increasing the occurrences of ice jams, by the spring flood being less pronounced, by an increased recurrence of extreme events and by low flows being lower and lasting longer than in the current climate (Boyer et al, 2010;CEHQ, 2012;Ouellet et al, 2012). Geomorphological effects of future climate on rivers remain difficult to ascertain (Kiss and Blanka, 2012), but it seems clear that sediment transport dynamics will be altered (Radoane et al, 2013).…”

The influence of an extended Atlantic hurricane season on inland flooding potential in the southeastern United States

“…Future work could extend this study to look at increase in flood risk not only due to the average tropical cyclone but also due the full range of tropical cyclones that a basin is likely to experience (the tropical cyclone with the maximum increase in discharge, the tropical cyclone with the minimum increase in discharge, etc.). For instance, given that tropical cyclones are likely to intensify (Bronstert et al, 2002;Frey et al, 2010;Greenough et al, 2001;Irish and Resio, 2013;Irish et al, 2014;Kostaschuk et al, 2001;Mousavi et al, 2011;Ouellet et al, 2012), flooding risk in an extended hurricane season likely could exceed the results presented in this paper, although May and December tropical cyclones likely could be weaker than mid-season storms. Further, more explicit modeling of future tropical cyclone dynamics using a stochastic approach, rather than average statistics, could potentially produce a more robust understanding of the effects of future climate dynamics on flood susceptibility.…”

“…When averaged over the 17-year period analyzed in this study, the number of days at risk of tropical-cyclone-induced flooding increases from 1.9 to 3.1 days yr −1 . While 3 day yr −1 may not seem substantial, it not only represents a 63 % increase, but it is also a conservative number, as it excludes predicted enhancements in the intensity and/or frequency of future tropical cyclones (Bronstert et al, 2002;Frey et al, 2010;Greenough et al, 2001;Irish and Resio, 2013;Irish et al, 2014;Kostaschuk et al, 2001;Mousavi et al, 2011;Ouellet et al, 2012). Further, this research does not consider synergistic effects due to the potential interplay between May and/or December tropical cyclones and midlatitude cyclones, which could increase precipitation and flooding risk even further.…”

“…However, there is some debate about changes in tropical cyclone frequency. Some research predicts that tropical cyclone frequency will increase (e.g., Greenough et al, 2001;Ouellet et al, 2012), while other research suggests that tropical cyclones are likely to intensify with global climate warming but occur less frequently (e.g., Irish and Resio, 2013;Kostaschuk et al, 2001).…”

“…Numerous studies have indicated that global climate warming may intensify tropical cyclones and is very likely to result in sea level rise (Bronstert et al, 2002;Frey et al, 2010;Greenough et al, 2001;Irish and Resio, 2013;Irish et al, 2014;Kostaschuk et al, 2001;Mousavi et al, 2011;Ouellet et al, 2012). Major hurricanes, those that are category 3 or higher on the Saffir-Simpson scale, are the most likely to intensify (Frey et al, 2010;Mousavi et al, 2011).…”