Floods

Intense rainfall can cause direct significant and long lasting impacts on transport operations, due to flooding, while indirectly impacting transport safety and bringing damage to transport infrastructure. Submerged roads and railway tracks become unusable, towns become inaccessible, movement of people and goods becomes disrupted, and floods could even lead to human casualties.

Knowledge about projected future changes in extreme rainfall events, and the projected changes in factors contributing to the occurrence of floods is needed. Such knowledge, combined with the sector's understanding of its vulnerability to these events, will allow transport organizations to develop strategies to minimize the potential risks brought about by changes in the characteristics of flood events in the future.

• Railways

  Heavy rain can lead to delays and line closures, due to flooding of the track or lineside equipment, or to flood-related debris on tracks; track damage (e.g. ballast washout); embankment scour and washout; bridge scour; flooding of depots; landslips; embankment landslides; overwhelmed railway drainage in cuttings.

  

• Roads

  Roads can suffer structural damage from water and debris, such as road edges erosion, subsidence and heave; embankments and culverts damage; landslips.

  

• Inland waterways

  Operations can be disrupted due to river flooding and debris accumulation. In anomalously strong currents, it can become difficult or impossible to manoeuvre large vessels safely. Additionally, debris accumulation can reduce the under-keel clearance of the vessels.

  

• Ports and airports

  Flooding at ports and airports limits their operability. Floods may also have indirect impacts: even if ports and airports can operate, access by road and/or rail can be limited by flooding external to the airport or port.

  

During the period 11th-14th August 2002, exceptionally heavy rain affected central Europe, which caused local flash floods. The rainfall was especially extreme in South Western Germany, Western and North Eastern of the Czech Republic. Several days later, the large rivers fed from these areas, including the Elbe, Vltava and Danube, flooded many cities and towns, including Prague and Dresden, with water levels reaching record heights.

Prague's historic centre was seriously damaged and the flow of the River Vltava reached 5300 m³/s, 20% more than the flood of 1845. About 40000 people were evacuated from their homes. The subway also suffered serious damage.

In Bratislava, Budapest and Vienna, the River Danube reached its highest level in decades. However, these cities did not suffer such major damage.

• According to the current generation of climate models, precipitation is projected to increase throughout this century in Northern Europe, and decrease in Southern Europe.
• The projected increase in heavy precipitation is related to the fact that warmer air can hold more water vapour, which in turn means there is more water available in the atmosphere to fall as rain.
• A marked increase in heavy precipitation events is also projected, which could lead to an increase in river flood risk, and without adaptive measures will bring greater flood damages (Kovats et al. 2014).

• The PRIMAVERA project is developing a new generation of advanced high-resolution global climate models, capable of simulating regional climate with greater fidelity.
• The increased temporal (sub-daily) and spatial resolution (typically around 25km) of the PRIMAVERA models will allow a better representation of physical processes leading to heavy convective precipitation, and of features related to flooding, such as storms, storm tracks, and blocking structures which often deflect the storms on their paths.
• Although convective storms are not explicitly resolved by the PRIMAVERA models, the increased temporal resolution will also allow some aspects of intense precipitation to be explored