In 2011, after months of little or no rain in central and eastern Europe, water levels on some parts of the Danube River fell to their lowest level in 70 years.

It’s one of Europe’s busiest shipping routes, but in November of that year, traffic ground to a halt on major sections of the Danube, and, on the Serbia-Hungary border, dozen of cargo ships were stranded.

In Romania, one of the country’s nuclear power stations was at risk of shutdown because of insufficient water for cooling, and, in Serbia, the drought revealed sunken World War Two ships and unexploded bombs.

In the lower Danube, low water levels also caused a decrease in bird and fish populations.

Kristian Yakimov, an ecologist and tourist guide in Bulgaria, speaks to Jacqueline Paine.

Eye-witness accounts brought to life by archive. Witness History is for those fascinated by and curious about the past. We take you to the events that have shaped our world through the eyes of the people who were there.

For nine minutes every day, we take you back in time and all over the world, to examine wars, coups, scientific discoveries, cultural moments and much more.

Recent episodes explore everything from how the Excel spreadsheet was developed, the creation of cartoon rabbit Miffy and how the sound barrier was broken.

We look at the lives of some of the most famous leaders, artists, scientists and personalities in history, including: the moment Reagan and Gorbachev met in Geneva, Haitian singer Emerante de Pradines’ life and Omar Sharif’s legendary movie entrance in Lawrence of Arabia.

You can learn all about fascinating and surprising stories, like the invention of a stent which has saved lives around the world; the birth of the G7; and the meeting of Maldives’ ministers underwater. We cover everything from World War Two and Cold War stories to Black History Month and our journeys into space.

(Photo: Cracked, muddy ground at the river bank of the Danube river. Credit: Alexanda Rilich/Getty Images)