Old Danube, Tolna, Hungary

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Hungary, Dél-Dunántúl, Tolna

The Old Danube lies in the area of Gemenc Forest, in Danube-Drava National Park, which is located 130km south of Budapest, between Szekszárd and Baja. About 180km2 from its territory are regularly flooded, which is unique not only in Hungary but also in Europe. The Old Danube can be found above the István Türr Danube bridge of Baja, on the right bank between 1480.8 and 1483.5 river km. This is an artificially designed oxbow created in 1897-1898.

Diverse flora and fauna species are recorded to be found in the floodplain of Gemenc, and this forest is reported to be the nesting place for the White-tailed eagle (Haliaeetus albicilla) and Black stork (Ciconia nigra), and it is also an important winter shelter for many other bird species. There are more than 70 fish species in the Hungarian section of the river, and from it is more than 30 protected and highly protected, and there are many amphibian species here like Triturus cristatus and Bombina bombina.

Submitted by
Klementina Keresztes-André
Approved by
Gireg Allain & Aleksey Malyshev
46.2030029, 18.8787174
Geographical region
Eastern Europe
Drainage Basin
River catchment
Water body type
Oxbow lake
Water body name
Old Danube
Water body part
Flood plain
Water body course
Water body: tributary of
Tributary name

Videos above and below water

Water Chemistry

Water information

Water type
Fresh water
Water color
Clear water
Water transparency
Concentration of sediments
Water temperature
1-24 °C
Water flow/curent

Chemical parameters

12 mg/l
5 mg/l
Dissolved Oxygen
70 %

Substrate in nature

Stone form
Submerged terrestrial vegetation

Aquatic Biotope

Date of collecting
Collecting area
Water depth
Air temperature


Affected by human activity
Affected by human activity
Surrounding area

Gemenc Forest is an integral part of the Geat Hungarian Plain with an area of almost 18.000ha, stretching 35km along the Danube between the villages of Bogyiszló and Báta. This area has a special mesoclimate: the annual rainfall is usually about 600mm, and characterized by late spring and early autumn frosts. Due to periodic and permanent flooding and the effects of the specific vegetation cover, the humidity is higher, and the large body of water also significantly affects the temperature. Number of larger oxbows and internal lakes in Gemenc nearly 30: the Old Danube is one of them.

The coast is dominated by the marsh vegetation, the typical plants for example Phragmites communis, Typha latifolia, Schoenoplectus lacustris, Mentha aquatica and Glyceria maxima. Although the most of the forests in Gemenc area now are man-made, artificial forests, nevertheless, efforts were made to create natural forest community that had been found in this area with White willow (Salix alba), Black poplar (Populus nigra), White poplar (Populus alba) and Common oak (Quercus robur).

The Forest’s fauna is very diverse, which is due to floods, as well as temporary lakes left after floods, which abound in food. The area is home to many species of waterfowl like Black-crowned Night-Heron (Nycticorax nycticorax), Grey heron (Ardea cinerea), Common kingfisher (Alcedo atthis), Smew (Mergus albellus) or Common goldeneye (Bucephala clangula). A large number of wild boars and Red Deer can be found here, as well as a stable population of otters and beavers.

Terrestrial vegetation:

  • Salix alba (Salicaceae)
  • Populus alba (Salicaceae)
  • Populus nigra (Salicaceae)
  • Quercus palustris (Fagaceae)
  • Quercus robur (Fagaceae)
  • Fraxinus excelsior (Oleaceae)
  • Ulmus minor (Ulmaceae)
  • Alnus glutinosa (Betulaceae)
Underwater landscape

The Old Danube riverbed is sand and gravel on wich there is a layer of silt was formed by the slow flow of water.
Due to the forest along the riverbank, there are many branches, fallen trees, roots and leaves in the water. The rich riparian vegetation is submerged during floods, providing a great hiding and spawning space for the fish.

In the oxbows and internal lakes, both floating and rooting seaweed vegetation can be found like Lemna minor, Myriophyllum spicatum, Hydrocharis morsus-ranae, Salvinia natans, Potamogeton crispus, Nymphaea alba or Nuphar lutea.


  • Tinca tinca (Cyprinidae)
  • Leuciscus idus (Cyprinidae)
  • Pelecus cultratus (Cyprinidae)
  • Abramis brama (Cyprinidae)
  • Blicca bjoerkna (Cyprinidae)
  • Abramis sapa (Cyprinidae)
  • Abramis ballerus (Cyprinidae)
  • Vimba vimba (Cyprinidae)
  • Rutilus rutilus (Cyprinidae)
  • Scardinius erythrophthalmus (Cyprinidae)
  • Chondrostoma nasus (Cyprinidae)
  • Alburnus alburnus (Cyprinidae)
  • Cyprinus carpio (Cyprinidae)
  • Stizostedion volgense (Percidae)
  • Sander lucioperca (Percidae)
  • Perca fluviatilis (Percidae)
  • Acipenser ruthenus (Acipenseridae)
  • Barbus barbus (Cyprinidae)
  • Lota lota (Lotidae)
  • Hypophthalmichthys molitrix (Cyprinidae)
  • Lepomis gibbosus (Centrarchidae)
  • Leuciscus leuciscus (Cyprinidae)
  • Gasterosteus aculeatus (Gasterosteidae)
  • Gymnocephalus cernuus (Percidae)
  • Aspius aspius (Cyprinidae)
  • Esox lucius (Esocidae)
  • Silurus glanis (Siluridae)
  • Chalcalburnus chalcoides mento (Cyprinidae)
  • Cottus gobio (Cottidae)
  • Gobio gobio (Cyprinidae)
  • Leucaspius delineatus (Cyprinidae)
  • Rhodeus sericeus (Cyprinidae)

Aquatic plants:

Wetland plants:

  • Mentha aquatica (Lamiaceae)
  • Phragmites australis (Poaceae)
  • Butomus umbellatus (Butomaceae)
  • Typha angustifolia (Typhaceae)
  • Typha latifolia (Typhaceae)
  • Sagittaria sagittifolia (Alismataceae)
  • Potentilla anserina (Rosaceae)
Threats to ecology

The Gemenc Forest is one of the largest contiguous floodplains in Europe, therefore it plays a particularly important role for native animals as it is one of the last natural shelters for them from humans. However, without a human intervention it can’t survive so Gemenc Forest and Wild Economy Zrt. has been responsible for conservation and wildlife management in the area since 1968.

Riparian zone

Trees near the aquatic habitat
Many -

Comment by the expert

Gireg Allain: Biotope research is very thorough and precise. We’re learning a lot about this particular area that’s being flooded, whether it’s the terrestrial environment or the aquatic flora and fauna. The bibliography is very rich, in websites but also with many books. The work of shooting is absolutely fantastic. The images are of quality, and the use of a drone offers us magnificent images. The splendid underwater images make us encounter a catfish, a pike, etc. and the images of the aquarium are also sumptuous. Bravo!

Aleksey Malyshev: The description of the biotope is successful. It was possible to add a relationship between fish and birds, for example, and other animals.