The Río Grande (or Río Guapay) in Bolivia rises on the southern slope of the Cochabamba mountains, east of the city  Cochabamba, at . At its source it is known as the Rocha River. It crosses the Cochabamba valley basin in a westerly direction. After 65 km the river turns south east and after another 50 km joins the Arque River at and an elevation of 2.350 m.