Ships on the entire German section of the Rhine could only sail partly loaded because of the low water, traders said.
'In Cologne, vessels are about 80 per cent empty; in other sections of the river, about 60-70 per cent empty,' one trader said.
Low water means that more ships are needed to move consignments which normally fit into a single vessel, and low water surcharges are being imposed. Cargo owners generally have to pay for the full ship even if it sails with a fraction of its normal load.
On the Danube, water levels have also fallen sharply, traders said. The river is so low that vessel owners generally have a right to refuse to fulfil transport contracts if they believe that their vessel will be endangered.
There was no immediate sign of relief for river shipping, with German weather forecast to be mainly dry this week to Friday, when rain is expected.
The Rhine is an important shipping route for commodities such as grains, minerals, coal and oil products including heating oil. It is a major route for Switzerland's commodity imports.