Drava

In ancient times the river was known as Dravus or Draus in Latin, and in Greek as Δράος and Δράβος. Medieval attestations of the name include Dravis (c. AD 670), Drauva (in 799), Drauus (in 811), Trauum (in 1091), and Trah (in 1136). The name is pre-Roman and pre-Celtic, but probably of Indo-European origin, from the root *dreu̯- 'flow'. The river gives its name to the dravite species of tourmaline.

Carpis

The Carpis (Greek: Κάρπίς) was a river which, according to Herodotus, flowed from the upper country of the Ombricans northward into the Ister (Danube), whence it has been supposed that this river is the same as the Dravus.

The Drava (along with one of its tributaries, the Slizza) and the Spöl are the only two rivers originating in Italy that belong to the Danube drainage basin. Its main left tributaries (from the north) are the Isel (contributes 39 m³/s), the Möll (25 m³/s), the Lieser (22 m³/s), the Gurk (30 m³/s) and the Lavant (12 m³/s) in Austria, and the Mur (166 m³/s) near Legrad at the Croatian-Hungarian border. Its main right tributaries (from the south) are the Gail (45 m³/s) in Austria, the Meža (12 m³/s) and Dravinja (11 m³/s) in Slovenia, and the Bednja (? m³/s) in Croatia.

Mean discharge is for the last station in the country mentioned in the source.

The sources of the Drava are located at the drainage divide between the market town of Innichen/San Candido and neighbouring Toblach/Dobbiaco in the west, where the Rienz River rises, a tributary of the Adige/Etsch. At Innichen itself the 16+ km (10 mile) Sextner Bach, originating near the Sextener Rotwand, joins the ~2 km (1¼ mile) long source creek. The river then flows eastwards and after 8 kilometres (5 miles) crosses into East Tyrol in Austria. At Lienz it flows into the Isel, sourced from the glaciers of the Venediger and Glockner Groups. The Isel (average discharge 39 m³/s) is almost three times larger than the Drava (14 m³/s) where they meet and, starting from the source of its tributary Schwarzach under the Rötspitze, the Isel (ca. 64 km; 40 miles) is also longer than the combined Drava and Sextner Bach (ca. 60 km; 35 miles) to that point.

The river then flows east into Carinthia at Oberdrauburg. The river separates the Kreuzeck range of the High Tauern in the north and the Gailtal Alps in the south, passes the Sachsenburg narrows and the site of the ancient city of Teurnia, before it reaches the town of Spittal an der Drau. Downstream of Villach, it runs along the northern slopes of the Karawanks to Ferlach and Lavamünd.

The Drava passes into Slovenia at Gorče near Dravograd, from where it runs for 142 kilometres (88 mi) via Vuzenica, Muta, Ruše, and Maribor to Ptuj and the border with Croatia at Ormož.

The river then passes north of Varaždin, after which it receives the Plitvica and Bednja from the right, and then Mura at the border with Hungary. It continues as a largely border river towards the southeast, receiving Gliboki and Bistra Koprivnička from the right. It passes the city of Barcs in Hungary from the south. It starts to be navigable, for about 90 kilometres (56 mi) in Croatia, from the confluence of the Čađavica to its mouth. It passes Belišće from the north, receives the Karašica from the right, and then passes the city of Osijek from the north. Afterwards, it enters the Kopački Rit wetland and merges into the Danube from its right.

The hydrological parameters of Drava are regularly monitored in Croatia at Botovo, Terezino Polje, Donji Miholjac and Osijek.

The Drava's mean annual discharge (Q, m³/s) at Drávaszabolcs (Hungary, 77.7 rkm). Period from 1995 to 2025.

Currently, there are 22 hydroelectric power plants on the Drava. The power plants are listed beginning at the headwaters:

The Drava is one of the most exploited rivers in the world in terms of hydropower, with almost 100% of its water potential energy being exploited. As the region of the river is a place of exceptional biodiversity, this raises several ecological concerns, together with other forms of exploitation such as use of river deposits.