South Morava

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: Gjilan 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 the 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. == Tributaries ==

The South Morava has 157 tributaries. The most important left tributaries are: Jablanica, Veternica, Pusta reka and Toplica. Right tributaries are: Vrla, Vlasina, Nišava (the longest) and Sokobanjska Moravica. == Economy ==

The South Morava has a significant potential for electricity production, and a huge hydroelectrical system (Vlasina- Vrla I-IV power stations) has been constructed in its drainage basin. To a certain extent, its waters are used for irrigation. The river valley's most important role is as a channel for transportation. It is the natural route for both railway and highway between Belgrade–Skopje–Thessaloniki. It is part of the Pan-European corridor X, and the route of the E75 Highway. ==Historical name==

Till early 20th century and beyond it has been also known as Bulgarian Morava (, Balgarska Morava; , Bugarska Morava). This historical name derives from the Ottoman times when it was considered that as a whole the river was a natural border between Bulgarians from the east side, and Serbs and Albanians from the west one. A detailed ethnographic map of the then mixed (Albanian, Serbian and Bulgarian) population of the western bank of Bulgarian Morava Valley was made by Hahn and Zach in 1861. == See also ==