Bridge Clogging in Belgium and Germany During the 2021 Floods.
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| Title: | Bridge Clogging in Belgium and Germany During the 2021 Floods. |
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| Authors: | Poppema, Daan W.1 (AUTHOR) d.w.poppema@tudelft.nl, Burghardt, Lisa2 (AUTHOR) burghardt@iww.rwth-aachen.de, Benet, Loïc3 (AUTHOR), Wüthrich, Davide1 (AUTHOR), Klopries, Elena‐Maria2 (AUTHOR), Dewals, Benjamin4 (AUTHOR), Erpicum, Sébastien4 (AUTHOR) |
| Source: | Water Resources Research. Nov2025, Vol. 61 Issue 11, p1-18. 18p. |
| Subjects: | Floods, Construction & demolition debris, Emergency management, Construction materials, Fluid dynamics |
| Geographic Terms: | Western Europe, Belgium, Germany |
| Abstract: | During summer of 2021, devastating river floods occurred in Western Europe as a result of extreme rainfall. At numerous bridges, debris accumulations were observed, exacerbating flooding upstream by impeding waterflow and sometimes contributing to bridge failure. Due to widespread building damage and flooding of settlements along the rivers, these accumulations differed markedly from classic logjams, revealing substantial amounts of man‐made objects. A new database of clogged bridges in Belgium and Germany (described in a separate data descriptor) was analyzed to characterize bridge clogging and determine the effect of bridge design, bridge location and hydraulic conditions. Results showed that nearly half of the debris volume consisted of man‐made materials, including building rubble, anthropogenic wood and vehicles. This created remarkably dense accumulations, highlighting the importance of further studying debris accumulations of mixed composition. Examination of the relations between bridge design and accumulation volumes found that bridges with narrow pier spacing (≤10 m) are more susceptible to extreme clogging. Blocking by the deck and railing also played a prominent role, in conjunction with blocking by the piers, as peak water levels at 85% of the analyzed bridges reached or exceeded the deck. Altogether, these findings can help to better understand bridge clogging effects on flood conditions, to design bridges with lower debris accumulation risks, and to inform future flood hazard assessments, flood risk mapping, and disaster response strategies, especially in urbanized regions. Plain Language Summary: In 2021, devastating river floods hit Western Europe. During these floods, floating debris built up in front of many bridges. This increased flooding by partly blocking rivers and contributed to the failure of bridges. Usually, accumulations mainly include trees, but this time they contained large amounts of building rubble and man‐made objects, from flooded and damaged buildings along the river. To study this issue, we documented bridge clogging during the 2021 flood in Belgium and Germany in a database. Analysis showed that approximately half of the documented debris was from man‐made materials, including building rubble, construction wood, cars and caravans. This resulted in remarkably dense accumulations, with more flow resistance and a larger increase in upstream water levels. This highlights that accumulations of mixed debris should be studied more in the future. The largest accumulations occurred at bridges with piers placed 10 m or less apart. Debris blocking by the deck and railing also played a prominent role, as most debris was blocked by flooded bridges, with a submerged deck. These findings can help designing bridges with lower risk of debris blockages, and inform disaster response strategies on where to expect debris accumulation during floods. Key Points: Analysis of debris accumulations at 71 bridges, detailing bridge characteristics and debris properties (volume, geometry, composition)Debris composition showed a surprisingly large fraction of man‐made materials (50%): mainly building rubble, construction wood and vehiclesAt 85% of the bridges, water reached or exceeded the deck, highlighting the importance of deck and railing design for bridge clogging [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
| Abstract: | During summer of 2021, devastating river floods occurred in Western Europe as a result of extreme rainfall. At numerous bridges, debris accumulations were observed, exacerbating flooding upstream by impeding waterflow and sometimes contributing to bridge failure. Due to widespread building damage and flooding of settlements along the rivers, these accumulations differed markedly from classic logjams, revealing substantial amounts of man‐made objects. A new database of clogged bridges in Belgium and Germany (described in a separate data descriptor) was analyzed to characterize bridge clogging and determine the effect of bridge design, bridge location and hydraulic conditions. Results showed that nearly half of the debris volume consisted of man‐made materials, including building rubble, anthropogenic wood and vehicles. This created remarkably dense accumulations, highlighting the importance of further studying debris accumulations of mixed composition. Examination of the relations between bridge design and accumulation volumes found that bridges with narrow pier spacing (≤10 m) are more susceptible to extreme clogging. Blocking by the deck and railing also played a prominent role, in conjunction with blocking by the piers, as peak water levels at 85% of the analyzed bridges reached or exceeded the deck. Altogether, these findings can help to better understand bridge clogging effects on flood conditions, to design bridges with lower debris accumulation risks, and to inform future flood hazard assessments, flood risk mapping, and disaster response strategies, especially in urbanized regions. Plain Language Summary: In 2021, devastating river floods hit Western Europe. During these floods, floating debris built up in front of many bridges. This increased flooding by partly blocking rivers and contributed to the failure of bridges. Usually, accumulations mainly include trees, but this time they contained large amounts of building rubble and man‐made objects, from flooded and damaged buildings along the river. To study this issue, we documented bridge clogging during the 2021 flood in Belgium and Germany in a database. Analysis showed that approximately half of the documented debris was from man‐made materials, including building rubble, construction wood, cars and caravans. This resulted in remarkably dense accumulations, with more flow resistance and a larger increase in upstream water levels. This highlights that accumulations of mixed debris should be studied more in the future. The largest accumulations occurred at bridges with piers placed 10 m or less apart. Debris blocking by the deck and railing also played a prominent role, as most debris was blocked by flooded bridges, with a submerged deck. These findings can help designing bridges with lower risk of debris blockages, and inform disaster response strategies on where to expect debris accumulation during floods. Key Points: Analysis of debris accumulations at 71 bridges, detailing bridge characteristics and debris properties (volume, geometry, composition)Debris composition showed a surprisingly large fraction of man‐made materials (50%): mainly building rubble, construction wood and vehiclesAt 85% of the bridges, water reached or exceeded the deck, highlighting the importance of deck and railing design for bridge clogging [ABSTRACT FROM AUTHOR] |
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| ISSN: | 00431397 |
| DOI: | 10.1029/2024WR039218 |
