Changes in Mediterranean flood processes and seasonality
-
Published:2023-08-11
Issue:15
Volume:27
Page:2973-2987
-
ISSN:1607-7938
-
Container-title:Hydrology and Earth System Sciences
-
language:en
-
Short-container-title:Hydrol. Earth Syst. Sci.
Author:
Tramblay YvesORCID, Arnaud Patrick, Artigue GuillaumeORCID, Lang MichelORCID, Paquet Emmanuel, Neppel Luc, Sauquet EricORCID
Abstract
Abstract. Floods are a major natural hazard in the Mediterranean region, causing deaths and extensive damages. Recent studies have shown that intense rainfall
events are becoming more extreme in this region but, paradoxically, without leading to an increase in the severity of floods. Consequently, it is
important to understand how flood events are changing to explain this absence of trends in flood magnitude despite increased rainfall extremes. A
database of 98 stations in southern France with an average record of 50 years of daily river discharge data between 1959 and 2021 was
considered, together with a high-resolution reanalysis product providing precipitation and simulated soil moisture and a classification of weather
patterns associated with rainfall events over France. Flood events, corresponding to an average occurrence of 1 event per year (5317 events in
total), were extracted and classified into excess-rainfall, short-rainfall, and long-rainfall event types. Several flood event characteristics have
been also analyzed: flood event durations, base flow contribution to floods, runoff coefficient, total and maximum event rainfall, and antecedent
soil moisture. The evolution through time of these flood event characteristics and seasonality was analyzed. Results indicated that, in most
basins, floods tend to occur earlier during the year, the mean flood date being, on average, advanced by 1 month between 1959–1990 and
1991–2021. This seasonal shift could be attributed to the increased frequency of southern-circulation weather types during spring and summer. An
increase in total and extreme-event precipitation has been observed, associated with a decrease of antecedent soil moisture before rainfall
events. The majority of flood events are associated with excess rainfall on saturated soils, but their relative proportion is decreasing over time,
notably in spring, with a concurrent increased frequency of short rain floods. For most basins there is a positive correlation between antecedent
soil moisture and flood event runoff coefficients that is remaining stable over time, with dryer soils producing less runoff and a lower
contribution of base flow to floods. In a context of increasing aridity, this relationship is the likely cause of the absence of trends in flood
magnitudes observed in this region and the change of event types. These changes in flood characteristics are quite homogeneous over the domain
studied, suggesting that they are rather linked to the evolution of the regional climate than to catchment characteristics. Consequently, this
study shows that even in the absence of trends, flood properties may change over time, and these changes need to be accounted for when analyzing the
long-term evolution of flood hazards.
Publisher
Copernicus GmbH
Subject
General Earth and Planetary Sciences,General Engineering,General Environmental Science
Reference63 articles.
1. Alaoui, A., Rogger, M., Peth, S., and Blöschl, G.:
Does soil compaction increase floods? A review, J. Hydrol., 557, 631–642, https://doi.org/10.1016/j.jhydrol.2017.12.052, 2018. 2. Ali, E., Cramer, W., Carnicer, J., Georgopoulou, E., Hilmi, N. J. M., Cozannet, G. L., and Lionello, P.:
Mediterranean Region, Cross-Chapter Paper 4 in: Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Pörtner, H. O., Roberts, D. C., Tignor, M., Poloczanska, E. S., Mintenbeck, K., Alegría, A., Craig, M., Langsdorf, S., Löschke, S., Möller, V., Okem, A., and Rama, B., 2233–2272, https://doi.org/10.1017/9781009325844.021, 2022. 3. Baker, D. B., Richards, R. P., Loftus, T. T., and Kramer, J. W.:
A new flashiness index: characteristics and applications to midwestern rivers and streams, J. Am. Water Resour. As., 40, 503–522, https://doi.org/10.1111/j.1752-1688.2004.tb01046.x, 2004. 4. Berens, P.:
CircStat: A MATLAB Toolbox for Circular Statistics, J. Stat. Softw., 31, ), 1–21, https://doi.org/10.18637/jss.v031.i10, 2009. 5. Berghuijs, W. R., Harrigan, S., Molnar, P., Slater, L. J., and Kirchner, J. W.:
The Relative Importance of Different Flood-Generating Mechanisms Across Europe, Water Resour. Res., 55, 4582–4593, https://doi.org/10.1029/2019WR024841, 2019.
Cited by
2 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|