Extreme Floods in the Eastern Part of Europe: Large-Scale Drivers and Associated Impacts

Monica Ionita,Viorica Nagavciuc

doi:10.3390/w13081122

Abstract

The role of the large-scale atmospheric circulation in producing heavy rainfall events and floods in the eastern part of Europe, with a special focus on the Siret and Prut catchment areas (Romania), is analyzed in this study. Moreover, a detailed analysis of the socio-economic impacts of the most extreme flood events (e.g., July 2008, June–July 2010, and June 2020) is given. Analysis of the largest flood events indicates that the flood peaks have been preceded up to 6 days in advance by intrusions of high Potential Vorticity (PV) anomalies toward the southeastern part of Europe, persistent cut-off lows over the analyzed region, and increased water vapor transport over the catchment areas of Siret and Prut Rivers. The vertically integrated water vapor transport prior to the flood peak exceeds 300 kg m−1 s−1, leading to heavy rainfall events. We also show that the implementation of the Flood Management Plan in Romania had positive results during the 2020 flood event compared with the other flood events, when the authorities took several precaution measurements that mitigated in a better way the socio-economic impact and risks of the flood event. The results presented in this study offer new insights regarding the importance of large-scale atmospheric circulation and water vapor transport as drivers of extreme flooding in the eastern part of Europe and could lead to a better flood forecast and flood risk management.

Highlights

Floods represent the most widespread natural hazard on Earth, with losses of numerous human lives and material damage of large proportions
The exceptional heavy rainfall over the period 24–26 July 2008 was followed by the largest floods, in terms of magnitude, which occurred on the upper section of the Siret and Prut Rivers, over the observational period
Prudhomme and Genevier (2011) [80] investigated the relationship between circulation types and flood across Europe, and they showed that hydroclimatological connections are more spatially coherent in winter than summer, while Jacobeit et al (2006) [81] found that flooding in central Europe is preceded by particular cyclone tracks, and these cyclone tracks differ seasonally and between regions

Summary

Introduction

Floods represent the most widespread natural hazard on Earth, with losses of numerous human lives and material damage of large proportions. According to the United Nations Office for Disaster Risk Reduction (UNISDR), floods constitute up to 43% of the total natural hazards. There is an increasing trend, in the damages caused by floods, the main causes being the irrational use of the valley’s rivers by deforestation, increasing economic activity on territories at risk, and global warming [1]. Alifieri et al (2017) [2] have shown that with a temperature increase of 2 ◦C, the related flood damages would rise by 170% compared to present levels, while for a 4 ◦C temperature increase globally, countries representing 73% of the global population would face a 580% increase in flood risk. That’s why the task of elaboration of the flood management plan is paramount to real flood prevention and protection against them

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