A natural phenomenon in Hungary could slightly shrink the country!

A striking—and at the same time instructive—natural process is currently taking place in Hungary: a new oxbow lake could soon form at one of the Ipoly River’s bends in the Hont region. This change is not only a scenic curiosity but also of geographical significance, as this section of the Ipoly forms part of the Hungarian–Slovak border. If the river cuts through its own bend, the tiny new island is likely to end up on the Slovak side, meaning Hungary’s territory could shrink ever so slightly.

How the river moves if left alone

The Ipoly is one of the few rivers in Hungary that has not been heavily regulated: it has no significant channel straightening, concrete embankments, or weirs. As a result, the river still meanders naturally, winding its way across the landscape. Water alternately erodes one bank and then the other, forming new bends over time.

This process, however, has almost completely disappeared on the Danube and Tisza. In the 19th century, river regulation “straightened” nature: rivers were contained to occupy less land, facilitate navigation, and reduce flooding.

But this comes at a cost.

Why it’s problematic to confine rivers to concrete channels

Researchers at the Budapest University of Technology and Economics’ Department of Hydraulic and Water Resources Engineering, including scientific associate Gergely Török, have been studying the Ipoly’s sediment balance and riverbed formation for three years. According to them, Hungary’s major rivers now face a significant sediment deficit caused by regulation, Telex reports.

If the banks are protected from the water, the river cannot wash away natural sediment and must compensate from its own bed. This leads to the riverbed lowering, which can result in:

• Lower water levels
• Increased drying
• Ecological damage

For the researchers, the Ipoly is like a time machine, showing how the Danube and Tisza would have functioned in their original states.

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Something is happening in Hont

“The bend at Hont is overdeveloped,” said Gergely Török in the latest episode of the documentary series Nem víznek való vidék (“Not a Place for Water”). On the outer curve, the current is strong and erodes the bank, while sediment is deposited on the inner curve. Each year, the neck of the peninsula becomes thinner.

Three years ago, according to Török, two cars could easily pass each other along the riverbank. Now, barely. “Soon, the river will bite its own tail,” he said.

Depending on the strength of flood waves, this process could be completed within 5–10 years. When it happens:

• The bend separates from the river
• An oxbow lake forms
• The peninsula becomes an island

What about the border?

Since the border follows the river’s thalweg (main channel line), the island that forms in the new oxbow lake will likely belong to Slovakia.

This means Hungary’s territory would shrink slightly.

However, researchers do not see this as a tragedy. As Török puts it:

“At another bend, we might actually benefit.”

Nature does not recognise political boundaries—the river builds here and there as it will.

Why this matters

It is important to remember that water is a living system, not just “liquid” in a channel. In an era of climate change, when Hungary is drying out increasingly quickly, understanding natural river processes is essential for retaining water, preserving habitats, and stabilising riverbeds.

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