The Ralja (Serbian Cyrillic: Раља) is a river in Šumadija region of Serbia, a 51 km long left tributary to the Jezava, a tributary of the Great Morava river. It also gives its name to the surrounding Šumadija's subregion of Ralja.
River Ralja near the village of Ralja (Smederevo)
|⁃ location||Kosmaj mountain, west of Velika Ivanča|
|Jezava, at Radinac|
|Length||51 km (32 mi)|
|Basin size||310 km2 (120 sq mi)|
|Progression||Jezava→ Great Morava→ Danube→ Black Sea|
The Ralja originates from the northern part of the Kosmaj mountain, north of the village of Velika Ivanča, in the Sopot municipality of the City of Belgrade. Almost from the source, the river valley is a route for the Belgrade-Niš railway. At the villages of Popović and Mali Požarevac, the Ralja turns straight to the east for the rest of its flow and also from this point, the Belgrade-Niš highway joins the railroad.
As it flows next to the Belgrade suburbs of Dražanj, Umčari and Živkovac, the Ralja divides Podunavlje region from the Ralja region of the low Šumadija, and leaves the City of Belgrade area at the village of Malo Orašje. After the villages of Binovac, Kolari, Vrbovac and Ralja, the river separates from the highway turning north at the village of Vranovo and empties into the one of several arms of Jezava at the Smederevo's suburb of Radinac.
- Miladinović, Slobodan Đ.; Gavrilović, Ljiljana M. "Estimates of endangerment and protection from torrential floods on Smederovo territory" (PDF). Retrieved 2018-06-01.