The River Po in northern Italy has fallen to historically low levels as the country endures its fourth heatwave of the summer. Wide stretches of dry riverbed are exposed near Pavia, and water supply and farming across the Po valley are under acute strain.

The Po is the country’s longest river and the drainage system for its most productive agricultural region. When it runs low, the effects are felt in ways that stretch well beyond the river itself.

What “historically low” means

River level records for the Po go back well over a century. Comparable summer lows have been recorded before — 2003, 2007, 2022 — but the frequency has increased sharply, and the four heatwaves of the current summer stand out even in a decade of unusual ones.

The 2022 drought was described at the time as the worst in seventy years. Comparisons with current conditions will need the data to complete, but the practical consequences are already the same: irrigation channels running dry, rice paddies in Piedmont without water at a critical growth stage, hydroelectric generation reduced, and saltwater intrusion pushing further up the delta into freshwater aquifers.

Why the Po is a special case

The Po basin drains about a quarter of Italy’s territory and produces around 40 per cent of its agricultural output by value — grain, rice, dairy and horticulture. It also supplies drinking water to some 17 million people and industrial water to a large share of the country’s manufacturing base.

This concentration means a single hydrological event has knock-on consequences across food supply, energy production and municipal water in ways that a diversified system would absorb. Italy is not diversified in this respect.

What has changed

Two factors interact. Warmer winters mean less snow accumulates in the Alps, so the meltwater that feeds the Po through the dry summer months has thinned. Warmer summers evaporate what does arrive faster, both from the river and from the reservoirs and irrigation networks that draw on it.

The system was engineered — canals, weirs, dams, distribution networks — for a hydrological pattern that has been shifting steadily over recent decades. It is not that it cannot be adapted. It is that adaptation on this scale takes years, and the pressure has been arriving faster than the works.

The visible signs

What the exposed riverbed near Pavia shows, at a level everyone can see, is that the standard European mental picture of Italy — cool rivers, terraced hills, endless water for wine and rice — is a snapshot of climatic conditions that are becoming less reliable. The country’s coral reefs, its glaciers, its major river are all showing the same underlying pattern, expressed differently in each system.

The Po will fill again this winter. The question that is now serious rather than speculative is what next summer looks like.

Sources

Euronews reporting from Pavia; historical Po hydrological data from the Italian Po River Authority (Autorità di Bacino Distrettuale del Fiume Po); Italian Ministry of Environment drought bulletins.