Managing Flood Hazard in a Complex Cross-Border Region Using Sentinel-1 SAR and Sentinel-2 Optical Data: A Case Study from Prut River Basin (NE Romania)

Cătălin I Cîmpianu,Andrei Urzică,Cristian C Stoleriu,Alin Mihu-Pintilie,Elena Huţanu

doi:10.3390/rs13234934

Abstract

In this study, an alternative solution for flood risk management in complex cross-border regions is presented. In these cases, due to different flood risk management legislative approaches, there is a lack of joint cooperation between the involved countries. As a main consequence, LiDAR-derived digital elevation models and accurate flood hazard maps obtained by means of hydrological and hydraulic modeling are missing or are incomplete. This is also the case for the Prut River, which acts as a natural boundary between European Union (EU) member Romania and non-EU countries Ukraine and Republic of Moldova. Here, flood hazard maps were developed under the European Floods Directive (2007/60/EC) only for the Romanian territory and only for the 1% exceeding probability (respectively floods that can occur once every 100 years). For this reason, in order to improve the flood hazard management in the area and consider all cross-border territories, a fully remote sensing approach was considered. Using open-source SAR Sentinel-1 and Sentinel-2 data characterized by an improved temporal resolution, we managed to capture the maximum spatial extent of a flood event that took place in the aforementioned river sector (middle Prut River course) during the 24 and 27 June 2020. Moreover, by means of flood frequency analysis, the development of a transboundary flood hazard map with an assigned probability, specific to the maximum flow rate recorded during the event, was realized.

Highlights

This paper aims to delineate the maximum inundation extent of a flood event that took place over a four day period in a complex cross-border region of the Prut River, which acts as a natural boundary between European Union (EU) country Romania and non-EU countries Ukraine and Republic of Moldova
In order to carry out this statistical operation within the study area, a sample of the maximum annual flow rates recorded at Rădăut, i-Prut gauging station in the last 42 years
Remote sensing and time series discharge data can offer an alternative solution for generating flood hazard maps, especially in complex cross-border regions such as in our study area

Summary

Introduction

When it comes to floods, Romania is among the most affected countries [1,2,3,4,5]. Starting at the beginning of 21st century, Romania witnessed flood events at increasingly high levels and frequencies, with floods occurring every two years (2005, 2006, 2008, 2010, 2013 and 2014) [4,6,7,8,9]. The negative consequences associated with the 40 major flood events recorded in Romania in the last 20 years (235,105 people affected, 10,731 people left homeless, 243 deaths, €2.6 billion worth of damage) ranks Romania as the second place in Europe after Russian Federation in terms of flood events incidence and people killed [10]

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Conclusion