Ice occurrences on the Vistula in Warsaw

Autor: dr Joanna Angiel    

We don’t often go to the Vistula on frosty days, because we have ever fewer such days. The Vistula is a fascinating river in winter “dress” as it is in its spring or summer attire. One can see the winter-style Vistula during a walk or a drive, or tram travel across Warsaw’s bridges, but it is not the same as observing it from close by. It is worth getting off the embankment and better still, to go to the right bank wetlands in Praga and get directly to the river. We will then notice various ice wonders on the river itself, as well as in the surrounding areas.

During frosty days and nights the fast flowing water cools down and characteristic spongy clusters of ice from the water current develop, called slush ice or frazil. It forms due to the presence of suspended solids in the water, which then become condensation nucleus. The mass of frazil, flowing down with the current, creates the characteristic “ice tables”.

We find border ice in areas where the speed of the river flow is smallest or the water is still. Frozen clusters of frazil are often incorporated into that ice. When the frosty weather lasts for long periods, the ice may cover large parts of the Vistula or the entire river. Then it is called sheet ice. Such occurrences have taken place from time to time, although today they are more seldom due to climate change.
When the state of the water changes during the spring thaw border ice breaks up and creates ice floes. They often pile up on the riverbanks during the fluctuations of the state of the water. Ice floes along the river sometimes create so-called ice jams.

We cannot only see ice phenomena, but we can also hear them. Do you know the sound of frazil brushing along the Vistula’s banks, or the sound of breaking ice?
And how does the frozen Vistula sand squeak under your feet or the river grass that is stiff from frost? You can experience this when you go to the Vistula on the next frosty day. You won’t regret it.

The project ‘Protecting the habitats of priority bird species of the Vistula Valley under conditions of intensive pressure of the Warsaw agglomeration’ (wislawarszawska.pl) has received a grant from the Financial Instrument for the Environment (LIFE+) and from the National Fund for Environmental Protection and Water Management.