This Europe: Tiber's revival hit by a water shortage

The old bedsprings and bicycles have been hauled from the river, the cascades of putrefying household refuse have been carted away, the towpaths have been cleaned, smart new floating jetties and gang planks and signs installed. The revival of the Tiber, announced with a fanfare back in March, has finally taken place.

The old bedsprings and bicycles have been hauled from the river, the cascades of putrefying household refuse have been carted away, the towpaths have been cleaned, smart new floating jetties and gang planks and signs installed. The revival of the Tiber, announced with a fanfare back in March, has finally taken place.

There are what they call "commentated" rides on the tourist launches, €10 (£7) for the round trip, and, for the intrepid few who have started to use the river to get to work or the shops, a day ticket on the river taxis costs a mere €2.

It's a brave start, but the Tiber has some way to go before it offers real competition to the Seine or the Thames. One problem, which nothing can be done about, is the depth of the river: it flows, and appears always to have flowed, at a very low level between its banks. One's views of the great sights – St Peter's, Castel Sant'Angelo and so on – are steeply angled; down at water level it's like being a small child in a crowd of adults, craning for a glimpse of the action. The city's life is all around but one is observing it from ankle level.

The other problem is that it's going to get even lower – and this may bring the bold initiative grinding to a halt. This week a professor of hydraulic engineering at La Sapienza University, Antonio Tamburino, glumly predicted: "When the Tiber dries in the summer, the boats may have to stop running." The minimum volume of water necessary for navigation, according to Professor Tamburino, is between 100 and 150 cubic metres per second; but in the summer the volume is likely to shrink to a mere 50 cubic metres.

And even if the boats can just about make it, he says, the city health authorities would be likely to put a stop to the service – because in the summer heat the proportion of sewage in the water increases to the point where it kills off so many fish that river trips become medically perilous, not to mention very smelly.

Professor Tamburino's solution is to open one or more of the dams feeding into the river. But dam water has its uses, notably for generating electricity. Complicated negotiations will be necessary; the city may have to reimburse the electricity authority for the loss. The Tiber's return to its days of glory may be somewhat delayed.