Nera (Tiber)

The Nera () is a river in central Italy that starts in the Marche region but flows mainly through the Umbria region. It is the main tributary of the Tiber river.
Geography.
The Nera river has a length of , and a drainage basin with an area of approximately .
Course.
The Nera river starts in the "Monti Sibillini", within the Monti Sibillini National Park (), at an elevation of about ., in the "comune" of Castelsantangelo sul Nera, Province of Macerata, Marche.
The river flows through the "comuni" of Castelsantangelo sul Nera, Viso and Ussita in the Marche and then, after about , it flows in the Umbria. After flowing through the province of Perugia, it gets in the province of Terni and keeps flowing to the east and flows through the city of Terni.
After flowing through the city of Narni, it gets into the Lazio region (Province of Viterbo) and soon finally flows in the Tiber river as a left tributary near the city of Orte.
Main tributaries.
Only the tributaries coming from the left of the Nera are of some importance; those coming from the right are small streams.
Left tributaries: