Prague's floods: what 2002 broke, what 2013 proved

Prague owes its postcard setting to the Vltava, and the river has never let the city forget it. Floods in 1342, 1432 and 1890 are recorded in chronicles and on marks cut into old walls. In the twenty-first century the lesson was learnt twice: first with a disaster in August 2002, then, in June 2013, with a test of what the city had built in response.

When the Vltava rose again in June 2013 and metro stations closed as a precaution, the city was ready in a way it had not been eleven years earlier. The floods, the defences and the warning system are described below, with what residents should do.

August 2002

In the second week of August 2002, after days of exceptional rain across Bohemia, the Vltava and its tributaries rose to levels not seen in generations. The flood crest reached Prague on 14 August. Large numbers of people were evacuated across the country, and in Prague the water inundated the lower parts of the Old Town, Malá Strana, Kampa, Karlín, Holešovice and other districts along the river.

The metro suffered the most, and the damage was in the news around the world. Water entered tunnels and stations on several lines, and a considerable part of the network was flooded. Sources differ on exactly how many stations were hit, because water entered stations and connecting tunnels in different ways; commonly cited accounts put it at close to twenty. Restoring service took months, and full operation on all lines came back only some time after the water had gone. The cost of the damage was very large.

Prague Zoo in Troja was flooded and its animals had to be evacuated or moved to higher ground, and a number died (the zoo's later rebuilding is part of its story in Prague Zoo: history, layout and visiting tips). Cultural buildings along the river were affected too. Throughout the country the flood caused deaths and damage in the billions of crowns. It is often described as a flood of the kind expected only about once in five hundred years, though such labels are statistical and do not mean it cannot happen again.

What the city built

After 2002, Prague City Hall, the Vltava River Board (Povodí Vltavy), the transport company and the state invested in protection. The measures fall into three groups, described here in outline.

The first is the river and its reservoirs. The Vltava cascade of dams south of Prague, including Orlík and Slapy, can hold back water in a flood and release it gradually. Operators adjust levels in advance when heavy rain is forecast. The cascade cannot eliminate a flood, but it can reduce the peak.

The second is physical barriers in the city. Permanent walls and mobile flood barriers, made of aluminium panels and posts that are erected along the embankments when a flood is expected, protect the Old Town, Malá Strana, Karlín, Holešovice and other districts. Setting them up takes time and needs forecasts several hours or days ahead, which is why warnings matter. Protection has been extended to areas such as Karlín that were hit hard in 2002, and projects continue in other districts.

The third is protection of infrastructure. The metro operator installed flood gates and sealed openings so that stations can be shut off from water, and procedures exist to close and drain stations. The metro network is described in Prague metro lines and network logic. Utilities and the zoo also upgraded their defences.

June 2013

In early June 2013 heavy rain again raised the rivers in Bohemia. The Vltava rose in Prague on 3 and 4 June, and the city activated its flood plan. Metro stations near the river were closed as a precaution, trams and buses were rerouted, and mobile barriers were put up. This time the barriers and other defences largely held and the damage in the capital was far smaller than in 2002, although other parts of the country, including towns on the Elbe in northern Bohemia, suffered flooding. The relative success was widely seen as a vindication of the post-2002 investment, though experts warned against complacency, since a flood larger than the one defences were designed for could still overtop them.

Lessons from the two floods

Engineers and officials drew several lessons. Forecasting mattered: in 2013 the warnings were earlier and better, allowing barriers to go up in time. Communication mattered: residents and businesses were told what to expect and where to find information. Coordination mattered: the city, the river board, the transport company, the fire service and the army work to plans that are rehearsed. And the underground spaces mattered most: the metro, car parks and cellars are where water does the greatest damage, and where closing openings in advance pays off.

There are also lessons about limits. The barriers are designed for floods up to a certain size; a flood beyond that could overtop them. Planners therefore treat the barriers as one layer among several, along with reservoirs upstream, warning, evacuation plans and sensible rules on building in flood zones. The Czech state also compensates some victims of natural disasters, but the rules and amounts vary and insurance is the main protection for property owners.

How warnings work

The Czech Hydrometeorological Institute (ČHMÚ) monitors rainfall and river levels, issues forecasts and warnings, and publishes real-time gauge readings on its website. Flood warnings are linked to three degrees of flood activity (stupně povodňové aktivity). The first, a state of vigilance, means that river levels are rising and watch should be kept; the second, a state of alert, means that a flood is likely and preparations begin; the third, a state of danger, is declared when a flood is occurring and protective measures are taken. At the higher levels, the city and the fire service take over coordination and authorities may order evacuations.

City Hall publishes flood-related information and instructions online, and the integrated rescue system works with the city districts. Residents in flood-prone areas, such as parts of Karlín, Libeň, Troja, Smíchov, Zbraslav and Lahovice, should know their local arrangements.

If you live or work near the river

Practical steps depend on where you are. Check whether your building is in a flood-risk zone, for which the Povodí Vltavy and the Ministry of the Environment publish flood-risk maps. Insurance companies assess flood risk when setting terms for property insurance, and policies vary in how they cover flood damage, so read the terms. Keep important documents in a safe place above ground level. Follow the alerts from ČHMÚ and the city, and heed evacuation orders.

For visitors, floods are rare, and events usually come with days of warning. The practical effects are on transport: when the water level rises, parts of the embankments and the metro may close, as covered in Prague public transport system explained. Hotels and tour operators will know the position.

A changing climate

Climate scientists expect more intense rainfall events in Central Europe, which makes flood protection a long-term issue. The city's strategy includes adapting rainwater management, restoring natural floodplains where possible, and planning future development with flood risk in mind. The costs of protection are borne by city and state budgets, discussed in Prague city budget: how money flows. Living with a river means accepting these costs as part of the price of the city's location.

Frequently asked questions

When was the worst flood in modern Prague?

August 2002, when the crest reached Prague on 14 August and the metro, zoo and riverside districts were flooded.

Did Prague flood again in 2013?

The river rose and metro stations were closed as a precaution, but the flood defences built after 2002 largely held.

Where do I find official flood warnings?

On the website of the Czech Hydrometeorological Institute, with local instructions from Prague City Hall.

How many degrees of flood activity are there?

Three: vigilance, alert and danger.

Look up the flood-risk map for your address on the river board's website before the next rainy season.