Oum El-Rbia

a river in western Morocco. The Oum el-Rbia is 556 km long. It rises in the Middle Atlas Mountains and empties into the Atlantic Ocean. A violent stream in the mountains, it flows at a much slower rate across the plains between the mountains and the ocean. Its main tributaries are the el-Abid and the Tessa. The Oum el-Rbia exhibits freshets, which are fed by rains in the winter and by melting snow from the mountains in the spring; the water level decreases sharply during the summer dry season. During the winter rains, the river has a mean flow rate of approximately 200 cu m per sec. There are hydroelectric power stations along the Oum el-Rbia and the el-Abid. Water from the Oum el-Rbia is used for irrigation.