| Hers-Vif | |
| Map: | Hers-Vif.png |
| Mouth Coordinates: | 43.3058°N 1.5525°W |
| Subdivision Type1: | Country |
| Length: | 135km (84miles) |
| Source1 Elevation: | ±1500m (4,900feet) |
| Discharge1 Avg: | 15m3/s |
| Basin Size: | 1350km2 |
The Hers-Vif (in French pronounced as /ɛʁs vif/, "Live Hers", as opposed to the slower flowing Hers-Mort, "Dead Hers"), also named Grand Hers or simply Hers, is a 135km (84miles) long river in southern France, right tributary of the Ariège.
The Hers-Vif rises at an elevation of about 1500m (4,900feet) near the Chioula Pass of the Pyrenees, approximately 6km (04miles) north of Ax-les-Thermes. It is the major tributary of the Ariège into whose right bank it flows 2km (01miles) upstream from Cintegabelle in the Haute-Garonne.
It flows some 30km (20miles) through the Pyrenees, descending 1100m (3,600feet) to the village of Peyrat, where it reaches a piedmont plain. Its valley widens as it traverses the plain, reaching the medieval city of Mirepoix, which marks the start of its lower valley.
Several rivers flow into it:
Departments and towns along its course are:
Prades, Bélesta, La Bastide-sur-l'Hers, Mirepoix, Mazères
The Hers is probably known as vif (intense or rapid in this context) because of its sometimes spectacular floods – that of 16 June 1289 having entirely destroyed Mirepoix. More recently, there have been: