The South Morava belongs to the Black Sea drainage basin, and its own drainage area is 15,696 km², of which 1,237 km² is in Bulgaria (through its right tributary Nišava).
Its average discharge at the mouth is 100 m³/s and it is not navigable.

South Morava has a composite valley, which means it consists of series of gorges and valleys in this order: Gnjilane valley – Končulj gorge – Vranje valley – Grdelica gorge – Leskovac valley – Niš valley – Aleksinac valley – Stalać gorge.
After breaking through the last, Stalać gorge, it meets the West Morava.

In macro-geological terms, the South Morava connects the Aegean basin with Pannonian basin.
This creates a phenomenon named "apparent flow inversion": it seems that the river from one lowland climbs up the mountains and then flows into another lowland.
However these two large geological basins are connected by the Grdelica gorge (Serbian: Grdelička klisura/Грделичка клисура).
The bottom of the gorge, where the river flows, is much lower than the mountains surrounding it, and of course the river flows downwards through the gorge.

The South Morava used to be 318 km long, and represented a longer and natural (flowing in the same direction) headwater of Great Morava.
Historically it sometimes caused severe floods.
But the river's meanders have now been shortened by almost 30 km; and today it is shorter than the West Morava.
However, the West Morava has always had bigger discharge.

Areas in southern Serbia where the South Morava flows have been almost completely deforested, which has caused one of the most severe cases of erosion in the Balkans.
As a result of this, the river brings large amounts of materials to the Great Morava, filling and elevating its river bed, which exacerbates the huge floods of its daughter river.
The South Morava belongs to the Black Sea drainage basin, and its own drainage area is 15,696 km², of which 1,237 km² is in Bulgaria (through its right tributary Nišava). Its average discharge at the mouth is 100 m³/s and it is not navigable.
South Morava has a composite valley, which means it consists of series of gorges and valleys in this order: Gnjilane valley – Končulj gorge – Vranje valley – Grdelica gorge – Leskovac valley – Niš valley – Aleksinac valley – Stalać gorge. After breaking through the last, Stalać gorge, it meets the West Morava.
In macro-geological terms, the South Morava connects the Aegean basin with Pannonian basin. This creates a phenomenon named "apparent flow inversion": it seems that the river from one lowland climbs up the mountains and then flows into another lowland. However these two large geological basins are connected by the Grdelica gorge (Serbian: Grdelička klisura/Грделичка клисура). The bottom of the gorge, where the river flows, is much lower than the mountains surrounding it, and of course the river flows downwards through the gorge.
The South Morava used to be 318 km long, and represented a longer and natural (flowing in the same direction) headwater of Great Morava. Historically it sometimes caused severe floods. But the river's meanders have now been shortened by almost 30 km; and today it is shorter than the West Morava. However, the West Morava has always had bigger discharge.
Areas in southern Serbia where the South Morava flows have been almost completely deforested, which has caused one of the most severe cases of erosion in the Balkans. As a result of this, the river brings large amounts of materials to the Great Morava, filling and elevating its river bed, which exacerbates the huge floods of its daughter river.
South Morava