Why do the Danube and Tisza rivers cause floods in Hungary?

Flooding in Hungary is primarily driven by the hydrological characteristics of the Danube River and the Tisza River, both of which experience significant seasonal fluctuations in water levels.12

The Tisza River, which rises in the Carpathian Mountains, lacks an extensive lake system to regulate runoff. This results in a dramatic contrast between its maximum and minimum levels, leading to three annual floods in early spring, early summer, and fall. A particularly severe flooding scenario occurs when high water levels in the Tisza coincide with similar conditions in the Danube; in such instances, the Tisza is unable to discharge effectively and flows back into its own course, causing widespread inundation.1

The Danube itself also floods twice annually, in early spring and early summer, with discharge levels during these periods reaching up to 10 times those of low-water seasons. To mitigate these risks, Hungary has constructed approximately 2,500 miles (4,000 km) of flood-control levees along its river systems.2