The UN recently issued a report warning of the effects of global warming on the world's major river systems. Increased evaporation, drought and irregular rainfalls are expected to leave water levels chaotic. Even Europe isn't immune. Drought this summer hit the Danube, Europe's second biggest river system, and closed much of it to navigation.
"Problems on the long waterway are literally coming to the surface. In Prahovo, a harbour in Serbia, due to the low water level, the rusty bows of German ships from the Second World War can be seen pointing skywards. The Germans scuttled a fleet there in the summer of 1944 to prevent ordnance coming into the hands of the advancing Russians and partisans. There are still 22 German vessels on the Serbian riverbed and more than one hundred on the Romanian side.