The Dropt is born near Capdrot (Dordogne) at an altitude of 160 m. Its basin extends over approximately 1 km² in the massif between the great valleys of the Lot and the Dordogne (Guyenne). It flows into the Garonne today at Caudrot (Gironde), at an altitude of 300 m, downstream from La Réole. Until recently, the Drot met a meander earlier, at Casseuil.