With castles and vineyards dominating the river banks near Kaub, just eight kilometres from the Lorelei rock, named for a siren who was said to lure sailors to their deaths, it would be easy to forget how important the area is to German commerce. It is roughly halfway between the inland ports of Koblenz and Mainz, and virtually all freight shipped from seaports in the Netherlands and Belgium to the industrial southwest of Germany passes through here. On a day in late October, Sep learned that the river was just 25 centimetres deep. That meant the water in the man-made shipping channel dredged near the center of the river was about 1.5 metres deep, down from an average of about 3.3 metres. Even with cargo at one-third its usual weight, his 282-foot freighter Rex-Rheni — the King Rhine — would have only centimetres of water under its hull. "I've never experienced so little water here," said Sep, who has been working on the river since 1982, the past 22 years on the Rex-Rheni. "It's becoming so low that it's very difficult for ships to pass." Wild tomatoes growing in the riverbed of the Rhine in Bonn, Germany. Credit:NT Times An exceptionally dry summer has caused havoc across Europe. A trade group in Germany put farmers' losses at several billion dollars. The German chemical giant BASF had to decrease production at one of its plants over the summer because the Rhine, whose water it uses to cool production, was too low.

Petrol stations in the region that rely on tankers to deliver fuel from refineries in the Netherlands have run out. And the wreck of De Hoop, a Dutch freighter that sank after an explosion in 1895 and is normally submerged, now lies exposed on the Rhine's banks. About half of Germany's river ferries have stopped running, according to the Federal Waterways and Shipping Administration, and river cruise ships are having to transport their passengers by bus for parts of their journey. Thousands of fish in the Swiss section of the river died because of the heat and low oxygen levels. Repairs underway to a groyne during low water levels on the Rhine in Assmanshausen, Germany. Credit:NY Times There are reasons to believe such weather will become more frequent with a warming climate. "Our research shows an increase in instability," said Hagen Koch, who studies rivers at the Potsdam Institute for Climate Impact Research. "The extremes are going to happen more often."

It's difficult to overstate the importance of the Rhine to life and commerce in the region. Rivers run through it. Credit:NY Times "It's simply the most important river in Germany," said Martin Mauermann, head of the hydrology and water management section of the federal body responsible for waterways. "It's like the thick branch in the middle of the tree." Roughly 80 per cent of the 223 million tons of cargo transported by ship in Germany each year travels the Rhine, which links the country's industrial heartland to Belgium, the Netherlands and the North Sea. An exact tally of how much is being diverted to rail and road is not yet available, but "it is a significant number," said Martyn Douglas of the German Federal Environment Agency. While most freight can simply — albeit often more expensively — be put on rails or wheels, some cannot. A shipping company, Kübler Spedition, specializes in heavy and oversize freight that cannot be carried for more than a couple miles on roads. Because ships carrying the heavy components of a wind farm can no longer reach the company's terminal in Mannheim, Kübler's storage area lies empty.

"It's effectively stopped the building of the wind farm entirely," said Robert Mutlu, who runs the terminal. The Rhine's flow relies not just on annual rainfall, but also on enormous long-term reserves of water, in the Alps. Melting snow and glaciers, as well as Lake Constance, feed the upper parts of the river, but with climate change, those reserves are lower, Koch said. The shipping lane could be made deeper, but that would take years, if not decades, and would cost millions. And even if that were to succeed, it would remove only one bottleneck on a river that is just starting to show how many trouble spots it has. New York Times