Iguaçu Falls flow doubles in 26 hours, passing September's peak

The flow of the Iguaçu River at the falls more than doubled in 26 hours. The gauging station run by Brazil's National Water Agency (ANA) beside the Hotel das Cataratas, inside the National Park, recorded 3,868 m³/s at 2pm on Wednesday (10) and 8,411 m³/s at 4pm on Thursday (11).

In litres per second, the unit usually quoted locally: the river went from 3.9 million to 8.4 million litres per second. At the last reading it was still rising.

The surge comes days after the storm that put Foz do Iguaçu under a red alert from the Civil Defence.

How that compares

The historic average flow at the falls is 1.5 million litres per second. Thursday's reading is therefore around 5.6 times the average.

This is the second peak of the month, and higher than the first. On 2 September the volume had already passed 8.3 million litres per second, according to the utility Copel, then fell back. The river started climbing again on the 8th.

Can you still visit? What is known now

Brazilian side: as this article was published, the official Cataratas do Iguaçu website carried no notice of a walkway or trail closure, and states that the park opens every day of the year.

The number to watch is this one: closures on the Brazilian side tend to happen when the flow approaches 9 million litres per second. Thursday's reading is below that, but the margin is small and the river was rising.

Argentine side: the Garganta del Diablo walkway has been closed since 3 August, when the park removed the structure as a precaution against the flood. There is no reopening date: it depends precisely on the river dropping and on a technical safety assessment. The other circuits on the Argentine side remain open.

Before setting out, check the live reading at the falls today and the walkway status on the park's official website.

Two common mix-ups

The brown water is not dirt. It is sediment carried by rain across the river basin. In flood periods the colour changes, and that is part of the phenomenon.

It has nothing to do with Itaipu. The dam sits on the Paraná River and does not control the volume of the Iguaçu, which is the river that feeds the falls.

What to expect on a visit

With the river this high, the spray on the walkways becomes far denser and the noise rises. In practice: wet decking, soaked clothes and a fogged camera lens. Bring a rain cover, closed shoes with good grip, and something to protect your gear.

It is also the falls at their highest volume, which many people consider the best time to see them, as long as the expectation is right: in a strong flood, visibility drops because the spray itself hides part of the view.

To pick the best day and time, see when to go.

Sources: Marco Três's own reading from the ANA gauging station beside the Hotel das Cataratas (Iguaçu National Park) · Copel (2 September peak) · official Cataratas do Iguaçu website · story and video: 100 Fronteiras, video by @fozcidadelinda.