Gharb Valley Irrigation

The Gharb Valley, located in the north-west of Morocco, is one of the country's most important agricultural areas. Of its 638,000 ha, 388,000 ha are arable and about 250,000 ha are irrigable.

Various programs have been installed throughout the 1960s and 1970s and to date, 105,000 ha have irrigation infrastructure. Gravity-fed irrigation covers 68% of the area, pressure irrigation 19 % and flood irrigation 13%.

We provided feasibility studies, an environmental impact assessment, design and tender documents for a 30,000 ha area. The main characteristics of the project area are the clayey to silty-clayey soil and the risk of flooding. With the construction of Al-Wahda Dam, 93% of the flooding will be controlled.

The remaining threats are effluents from the Oued Sebou, downstream of the dam. An intensive drainage network and control of the overflows from Oued Sebou are necessary to secure and improve agricultural production. Main components include: a 100 km main canal of 4 m³/s capacity, 5 pumping stations, 5 night-storage reservoirs, and about 500 km of concrete-lined secondary canals. We also modelled the Al-Wahda Dam operations and the groundwater regime, made recommendations for administrative reform, tariff structure and fee-collection procedures.