The
Mamoré is a large river in
Bolivia and
Brazil, which unites with the
Beni to form the
Madeira, one of the largest tributaries of the
Amazon. It rises on the northern slope of the Sierra de Cochabamba, east of the city of
Cochabamba, and is known as the
Chimoré down to its junction with the
Chapare. Its larger tributaries are the
Chapare,
Secure,
Apere, and
Yacuma from the west, and the
Ichilo,
Guapay, Ivari, Manique, and
Guapore from the east. Taking into account its length only, the Guapay should be considered the upper part of the Mamore; but it is shallow and obstructed, and carries a much smaller volume of water. The Guapore also rivals the Mamore in length and volume, having its source in the
Parecis plateau,
Mato Grosso, Brazil, a few miles from streams flowing north-ward to the
Tapajos and Amazon, and southward to the
Paraguay and
Paraná rivers. The Mamore is interrupted by rapids a few miles above its junction with the Beni, but a railway 300 km long has been undertaken from below the rapids of the Madeira. Above the rapids the river is navigable to
Chimore, at the foot of the sierra, and most of its tributaries are navigable for long distances. In 1874, Franz Keller gave the outflow of the Mamoré at mean water level, and not including the Guapore, as 41,459 cm
3/sec (2,530 cub. in. per second), and the area of its drainage basin, also not including the Guapore, as 24,299 km
2 (9,382 square miles).