From Germany's Black Forest, to Romania’s Sulina town, the Danube River has shaped over time 10 countries and countless communities and cultures. Today, 83 million people live in the Danube river basin, out of which over 20 million directly depend on the Danube for drinking water.

Shellfish, fish and crayfish aplenty until the 1830s

But what made the Danube so alluring, that people decided to stay here? Nowadays, it may be dificult to imagine how the Romans saw the Danube and it is even more difficult to imagine what the river was like when the first migratory peoples decided to settle on the banks of the Danube for the first time. Or what life around the Danube looked like during the Industrial Revolution, when various discoveries by scientists advanced the development of factories and plants.

But we can say for sure that in those times there were fish, more fish than today, there were birds in much greater numbers than today, but also other species of plants and animals both in the river and in the Danube wetlands. The notes of the archaeologists and historians Dumitru Berciu and Eugen Comşa describe the area as follows: “the geographic environment from Balta Verde and Gogoșu (editor’s note: on the Romanian bank of the Danube) show a great abundance and variety of livelyhoods: soil fertility, an abundance of fish in the waters of the Danube, in its ponds and streams, bigger or smaller ones, like Blahnița,  as well as an abundance of game in the brooks and neighbouring forests and of wood necessary for the household”. What they are describing are the benefits of wetlands which today we call environmental services.

There are even older accounts about the Danube, some travelers from more distant times described the abundance of species in the waters of the Danube basin: “sturgeons and catfish of amazing sizes are caught here; there is shellfish, fish and crayfish aplenty, that you wouldn’t believe it if you didn't see it with your own eyes,” says Bishop Marco Bandini in 1648. This is how the river was described when it was still flowing freely.

But gradually, the sturgeon giants from the depths of the waters could not cross all the 2857 km of the Danube. The first dams appeared in Austria in 1830, and the first hydropower plant on the Danube was built in 1927 (Vilshofen). Since then, over 60 hydropower plants built on the Danube have contributed over time to the loss of ecosystems and the benefits these offered to the communities living along the river. The largest hydropower plant on the Danube is the Iron Gates I, which has led to a number of changes in the natural functioning of the river and its ecosystems. Because of the dam, sturgeons, the largest freshwater fish in the world and a symbol of the Danube, can no longer migrate upstream for breeding. Today, only the Lower Danube sector, between the Iron Gates and the Black Sea, is still characterized by uninterrupted water flow.

The 1960s, with more dams in the Danube floodplains

Another certainty is that the waters of the Danube were sometimes calmer and other times more turbulent, sometimes lower and other times, high. And people stayed close to the river, despite its temper… Or maybe because of it. Because the high waters cleaned the ponds by the river and allowed the fish to have access to quiet areas, where they could lay their eggs. And the undammed floodplains absorbed the excess water, like a sponge, keeping people safe.

We know for certain that floods and droughts have always existed, and the Danube and its wetlands continued to function efficiently and naturally until the 1960s, when the floodplain was dammed, dried up and transformed. Most of the areas once filled with fish, birds, reed, became agricultural land. These new lands could not cope with the floods as well as the wetlands did. Because when floods came, the large amount of water  could no longer flow into the river floodplain,  which  in turn lead to catastrophic floods in inhabited areas. Moreover, the interruption of the river's connectivity with the weltands led to changes in the quality of soils used intensively in agriculture, soils that were formed by periodic flooding and river sediments.

We also know for a fact that there will be more droughts and floods, and we also know how we can deal with them. But we do not know exactly how much or how little it will rain in 20-30 years from now, how much or how little water will reach the Danube and when, exactly.

A clear trend of increasing temperatures in the Danube basin has been identified, which will determine in the future the how the climate here will change. There is a good chance that seasons with more heavy rains and seasons with less water in the soil and in the groundwater will alternate. These large-scale changes will most likely lead to a decrease in the amount of water constantly available for humans and nature, predicting large variations in the flows of the Danube and tributaries in the short term and with short periods during the year when we enjoy snow. And yet, since it is largely accepted that long-term climate forecasts are uncertian, one question begs an answer: how accurately can solutions such as dams, dredging, river regulation be designed and at what costs can these works be done in order to eliminate the risks of great damages because of extreme weather events in the Danube floodplains? Hard to say exactly.

Nature based solutions

What is certain is that we can use nature based solutions to reduce the risks of drought and floods, in order to prevent unfortunate events. The connection between the Danube and its wetlands must be re-established in order to function efficiently, naturally and for the benefit of the people, with shellfish, fish and crayfish aplenty.

We are working to restore the ecological aquatic corridors for migratory fish species in the Danube basin. Thus, through the MEASURES project we are developing and testing a methodology for mapping migratory fish habitats, a first step towards restoring ecological corridors, and we are also developping a strategy, with broad participation and acceptance of stakeholders, to maintain or restore functional corridors. We are also carrying out sturgeon restocking activities - 8000 younglings have been released so far in the Danube, in Romania and Hungary.

Photo: © WWF-România/ Cristian Mititelu-Răileanu