The Manzanares () is a river in the centre of the Iberian Peninsula, which flows from the Sierra de Guadarrama, passes through Madrid, and eventually empties into the Jarama river, which in turn is a right-bank tributary to the Tagus. In its urban section, the Manzanares River was modified to create a section of water several meters deep, in some parts navigable by canoes. This project of channeling and damming has been partially reversed in a re-naturalization project. Course Sources The Manzanares has its sources in the southern slope of the , a branch of the Sierra de Guadarrama (the main eastern section of the Sistema Central), in the municipality of Manzanares el Real, in the Madrid region. It is formally called Manzanares after the confluence of the arroyo de la Condesa and the Arroyo de Valdemartín. The Arroyo de la Condesa is in turn born in the , a traditionally resilient snowdrift, and its watershed comprises the slopes in between La Maliciosa (2,227 m), the Alto de las Guarramillas—aka the (2,258 m)—and the (2,282 m). The Arroyo de Valdemartín's watershed spans from the Alto de Valdemartín to the Cabeza de Hierro Menor (2,373 m). Upper course The upper river basin is protected as the Parque Regional de la Cuenca Alta del Manzanares, a nature reserve which is recognised as a biosphere reserve by UNESCO. The Manzanares flows in a south-eastern direction from its sources, and passes through the medieval town of Manzanares el Real where it is dammed to form the Santillana reservoir, one of the most important water supplies for the capital. The river then takes a southern direction and enters the Monte de El Pardo, an ecologically valuable area on the edge of Madrid. Urban course The river was canalised where it passes through the built-up areas of the city. In the 21st century the river was restored to provide biodiversity and facilities for Madrid residents. The Manzanares skims past the westernmost part of the city and further downstream serves as a dividing line between the old centre of the city and the Carabanchel and Usera neighbourhoods to the southwest. It is along this stretch that it passes next to Atlético Madrid's former football ground, the Vicente Calderón. The river leaves the city at its southernmost tip. Lower course It makes a strong eastern turn which takes it past the village of Perales del Río. It empties