Oum Er-Rbia is a river in central Morocco

Morocco

Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...

. The river is 555 km long and is the longest in the country. With an average water debit of 105 m³/s, Oum Er-Rbia is the second largest river in Morocco after the Sebou River

Sebou River

Sebou is a river in northern Morocco. The river is 458 kilometres long and has an average water flow of 137 m3/s, which makes it the largest North African river by volume. The source is in the Middle Atlas mountains. It passes near the city of Fes and discharges to the Atlantic Ocean in Mehdia...

. It takes source in the Middle Atlas

Middle Atlas

The Middle Atlas is part of the Atlas mountain range lying in Morocco, a mountainous country with more than 100,000 km² or 15% of its landmass rising above 2,000 metres. The Middle Atlas is the northernmost of three Atlas Mountains chains that define a large plateaued basin extending eastward...

 and passes through the city of Khénifra

Khenifra

Khenifra is a city in northern central Morocco, surrounded by the Atlas Mountains.-External links:*...

 and comes in the Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 in Azemmour

Azemmour

Azemmour or Azamor |The Olives]]"; ) is a Moroccan city, on the left bank of the Oum Er-Rbia River, 75 km southwest of Casablanca. Although it was a dependency of the King of Fez, Azemmour had great autonomy. In 1486 its inhabitants became vassals and tributaries of João II of Portugal...

. Oum Er-Rbia has six dams, the most important of which is Al Massira Dam

Al Massira Dam

The Al Massira Dam is a gravity dam located south of Settat on the Oum Er-Rbia River in Settat Province, Morocco. Completed in 1979, the dam provides water for the irrigation of over of farmland in the Doukkala region. The dam's hydroelectric power plant also generates 221 GWh on average...

. Its most important tributaries

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 are El-Abid River, Tessaoute River, and Lakhdar River.

The original Berber name, is Asif n Isaffen, meaning the river of rivers.