Morocco’s Al Wahda Dam exceeds 82% capacity as water management intensifies

Sunday 27 - 17:00

With more than 2.82 billion cubic meters of water in storage, Al Wahda Dam is entering the next rainy season with substantial reserves while maintaining a careful approach to flood management and reservoir capacity.

Located on the Oued Ouargha in Morocco’s Ouazzane province, the dam plays a central role in managing water resources across the Sebou Basin. With an overall storage capacity of around 3.8 billion cubic meters, it is the country's largest hydraulic facility and one of Africa's major dams.

Its functions extend well beyond water storage. The reservoir helps regulate supplies for agriculture, contributes to hydroelectric generation and supports drinking-water needs in surrounding areas, making it an important component of regional economic activity.

Strong reserves provide room for strategic management

Morocco's latest hydrological season brought exceptionally high water inflows. Nearly 3.8 billion cubic meters entered the country's reservoirs, equivalent to around 169% of the annual average.

At Al Wahda, the result is a storage level exceeding 2.82 billion cubic meters, representing more than 82% of the reservoir's total capacity.

The high level provides an important water reserve, but it also requires careful management ahead of the next rainfall period. Maintaining sufficient free capacity is essential for limiting the risks associated with potentially heavy inflows and flooding.

Water managers are therefore monitoring reservoir levels and incoming flows on a daily basis while continuing maintenance operations on the dam's infrastructure.

Controlled releases can be adjusted according to rainfall patterns and the volume of water reaching the reservoir.

Daily releases support irrigation and power generation

Mustapha Tantaoui, director of Al Wahda Dam, said the facility is currently releasing around 3 million cubic meters of water per day.

These releases are primarily intended to support irrigation requirements downstream of the Oued Ouargha and across the Gharb plain. Part of the released water is also used in hydroelectric production, allowing the reservoir to serve several functions simultaneously.

The management strategy reflects the need to balance immediate water requirements with the preservation of storage capacity ahead of the next major rainfall events.

Measuring sediment buildup inside the reservoir

Water management at Al Wahda is also increasingly dependent on detailed knowledge of how the reservoir itself is changing.

Teams are conducting bathymetric surveys to measure water depths and map the underwater topography of the reservoir. The surveys make it possible to assess the accumulation of sediment and determine how much storage capacity has been affected by siltation.

The information collected is also used to update height-area-volume curves, providing managers with a more accurate picture of the reservoir's effective storage capacity.

For a large and ageing structure such as Al Wahda, this information is particularly important. Sediment accumulation gradually occupies part of the space that would otherwise be available for water storage, potentially reducing the reservoir's useful capacity over time.

A nationwide survey of major reservoirs

The bathymetric work at Al Wahda forms part of a broader effort by Morocco's hydraulic basin agencies to assess sedimentation in major reservoirs across the country.

The programme covers ten large dams: Oued El Makhazine, El Cherif El Idrissi, Nakhla, Al Wahda, El Mansour Eddahbi, Ghiss, Mohammed V, Oued Za, Mechraa Hammadi and Hassan Addakhil.

The objective is to build a more precise national picture of sediment accumulation and the resulting changes in reservoir capacity.

Such data can help water authorities refine forecasts, improve reservoir operations and better anticipate how much water can effectively be stored during future hydrological seasons.

Preparing for rainfall while protecting the water reserve

The situation at Al Wahda illustrates the increasingly complex task of managing Morocco's water infrastructure. High reservoir levels provide an important buffer after a strong rainfall season, but they also require sufficient capacity to accommodate new inflows.

For managers, the challenge is therefore not simply to retain as much water as possible. It is to maintain the right balance between securing supplies for agriculture and other users, generating hydropower and preserving enough space to manage future floods.

With more than 2.82 billion cubic meters already stored, Al Wahda begins the coming rainy season from a position of substantial reserves. Daily monitoring, controlled releases and increasingly precise knowledge of sediment accumulation will determine how effectively that reserve can be managed in the months ahead.