 The Guaiquivilo flows northwardly along a typical interandean longitudinal valley.On its left bank the Guaiquivilo is flanked by the Melado sierra, which has peaks that often surpass 2.500 mt and which constitute a natural barrier between the Guaiquivilo basin and those of the rivers Longaví, Achibueno and Ancoa, all tributary of the river Loncomilla, which, in its turn, is the main tributary of river Maule.On its right bank, the Guaiquivilo is joined by the river San Pedro or La Puente which is born from a glacier related to the San Pedro (or Las Yeguas) volcano.