Eastern European grain traders have had to switch to more expensive means of transportation as exports via the Danube River are blocked because of low water levels. Traders have had to export by road and to a lesser extent by railway, despite the cost per unit being significantly higher and eroding margins.

River cruisers booked on popular Christmas Markets sailings this month on the Rhine and Danube Rivers are anxiously watching weather reports and -- in a rare cruising turnabout -- hoping for rain. Why? Water levels in Europe have been unseasonably low, wrecking havoc on river cruise itineraries the last few weeks. Here's the current situation when traveling with Uniworld, Viking, Avalon Waterways, or Grand Circle.

Commercial traffic on the Bulgarian stretch of the Danube river is reported to be virtually halted due to excessively low levels of the river waters. 16 vessels have been stranded at the port of western Bulgarian Danube city of Vidin, where the water level surveillance service has measured just 83 cm.

The construction of the second Bulgarian-Romanian Danube bridge has been affected by the record low levels of the great European river. The record low waters of the Danube, the lowest since 1941, have made it hard to access the last pillar of the bridge between Bulgaria's Vidin and Romania's Calafat.

Passengers embarking on Christmas markets cruises on Europe's Rhine and Danube Rivers are still facing uncertainty as to whether their ships will actually sail, due to low water levels on these rivers. While many river cruisers worry about the possibility of their cruise turning into a bus tour without any additional compensation or advance warning, at least one line is reaching out to travelers.

"European Christmas Enchantments" takes you on a trip through those special cities of Germany, France, Switzerland and Austria, whose Yuletide traditions extend back over several centuries, during the weeks leading up to Christmas. The app costs EUR 2.99 (USD 3.99) and is now available on the iTunes AppStore. It is compatible with iPad and iPad 2 running iOS 4.2 or later.