What to know - Flood

What to know?

Flood is the flooding of an area where there is usually no water. It originates mainly from heavy and prolonged rainfall that can swell rivers to overflowing, bursting their banks and flooding the surrounding area. However, not all waterways occur and behave the same way. For example, torrents become natural rivers only when heavy rain falls. On the other hand, underground streams cannot be seen because they are artificially covered for long tracts. For these, as for sewer systems, the failure to contain excess rainwater can lead to floods. 

In its Civil Protection Plan, the municipality indicates flood risk areas due to small rivers, underground streams, torrents and sewer networks, and areas that may be affected by the overflow of large rivers, indicated in the Pgra - Flood Risk Management Plan carried out by District Authorities or Regions and Autonomous Provinces. The Civil Protection Plan also includes potentially critical situations at riverbanks, bridges, underpasses, and watercourse narrowings. 

The bigger the stream, the greater the ability to forecast. The rise in water level in a large river occurs gradually. This allows constant monitoring and primarily preventive actions. In contrast, the water level of small rivers or streams can grow very quickly, with reduced intervention times. In these cases – as for the rivers, artificially covered streams, and sewerage – it is not always possible to predict flooding, let alone when and where it will occur. Weather forecasts only indicate the likelihood of rainfall in a large area, not the occurrence in one place or another. 

In addition to the regular maintenance of waterways and sewage systems, it is also possible to carry out structural works (e.g., build banks), limit urban development in flood-prone areas, use warning systems, supervise civil defense planning, promote training exercises, and, finally, raise public awareness. 

The Regions and Autonomous Provinces operate the national warning system under the coordination of the Civil Protection Department. Pivotal to the system is the network of functional centers, which computes weather forecasts and their ground effects. Based on this information, each Region and Autonomous Province evaluates dangerous situations and forwards color-coded alerts (green, yellow, orange, and red) to local civil protection systems. Mayors activate their Civil Protection Plans, inform citizens about risk situations, and decide what actions to take to protect the population. 

Knowing if the area where you live, work, or stay is exposed to flood risk helps to prevent and better deal with emergencies. Remember:  

  • It is essential to know what are the typical floods in your territory; 
  • If floods have affected your territory in the past, they are likely to occur also in the future;  
  • In some cases, it is difficult to determine precisely when and where floods will occur, and you may not be alerted in time;  
  • It is essential to know the meaning of the warning system color codes (green, yellow, orange, and red);  
  • During a flood, water can rise suddenly, even by one or two meters in a few minutes; 
  • Some places get flooded sooner than others. At home, the most dangerous areas are cellars, basements, and ground floors; outdoors, underpasses, sections near banks and bridges, steeply sloping roads, and generally all areas lower than the surrounding area are most at risk;
  • The power of water can also damage buildings and infrastructure (bridges, embankments, dikes), and the most vulnerable ones could suddenly fail or collapse.