| Al Wahda Dam | |
| Name Official: | Barrage Al Wahda |
| Dam Crosses: | Ouergha River |
| Location: | M´Jaara, Ouezzane Province, Morocco |
| Dam Length: | 2600m (8,500feet) |
| Dam Height: | 88m (289feet) |
| Dam Volume: | 28e6m3 |
| Spillway Type: | Service, controlled chute |
| Spillway Capacity: | 13000m3/s |
| Construction Began: | 1991 |
| Opening: | 1997 |
| Res Name: | Al Wahda Reservoir |
| Res Capacity Total: | 3800e6m3 |
| Res Catchment: | 6200km2 |
| Res Surface: | 123km2 |
| Plant Turbines: | 3 x 80MW Francis-type |
| Plant Capacity: | 240MW |
| Plant Annual Gen: | 400GWh |
| Plant Commission: | 1997-1998 |
| Location Map: | Morocco |
| Coordinates: | 34.5983°N -5.1975°W |
Al Wahda Dam, formerly known as M'Jaara Dam, is an embankment dam on the Ouergha River near M´Jaara in Ouezzane Province, Morocco. It was constructed for flood control, irrigation, water supply and hydroelectric power production. It is the second largest dam in Africa and the largest in Morocco. It was described by Land Ocean Interactions in the Coastal Zone (LOICZ) as "the second most important dam in Africa after the High Aswan dam."[1]
In 1988, the Board of Water and Climate considered the dam and eventually it was recommended for development.[2] Construction began in 1991, the dam began to create its reservoir in 1996 and was inaugurated on March 20, 1997, by King Hassan II.[3] A total of 14000000m2 of material were excavated during construction.[4]
The dam is an earthen embankment type made of of material and of concrete. It is tall at its highest point and the main portion of the dam is long. Directly to the north and adjacent to the spillway is a saddle dam that is long and high. The dam's spillway, in its center is controlled by six floodgates and has a discharge capacity in excess of .[3]
The power plant, at the dam's toe and adjacent to the spillway is supplied with water via a diameter and long pipe which in turn transfers the water into three penstocks. Each of which is in diameter in length. This scheme provides of hydraulic head and up to to the Francis turbines.[3] Each turbine powers an generator for a total installed capacity of .[5]
The dam has had a positive impact downstream by supplying water for drinking and irrigation. In addition, it has helped reduce floods in the Gharb region along the Ouergha and Sebou Rivers by 90%. It provides water for the potential irrigation of over 110000ha.[2] Electricity produced by the dam's hydroelectric power station also alleviates the burning of of fossil fuels a year along with serving peak energy demand. The dam's reservoir though has a high rate of siltation and it is estimated to lose of storage each year. The silt trapped in the reservoir also doesn't reach the coastal estuary which increases erosion along the coast.[6]