Assessment and Provision of Environmental Flows in Mediterranean
Review of certain basic elements for the assessment of environmental flows in the Lower Moulouya
Basic Concepts, Methodologies and Emerging Practice

20 July 2004

par Web Team

The Moulouya Basin is in a situation of structural water deficit. The highly irregular precipitation and run-off rates limit the possibilities of rain-fed agriculture and of the potable and industrial water supply, making it necessary to regulate water flow by the construction of the Mohamed V-Mechra Homadi hydraulic complex and annexed constructions.


The Moulouya Basin has not yet been the object of an integrated study allowing the definition of the conditions required for the allocation of an environmental flow. Nevertheless, a certain number of hydrological, sedimentological, morphological, environmental, ecological and socio-economic studies, each with specific objectives, have been carried out separately on this Basin. The most important of these studies, though it is not up to date, is the one that has allowed the Water Research and Planning Case Study: Resource Kit on Environment Flow Concepts, Methods and Emerging Practices Page 6 Authority (DRPE) to establish a Master Plan for Water Management in the Moulouya Basin (CSE, 1992). The principal results of these studies are as follows:

1- Establishment of water need scenarios and a management plan for the future:

On the basis of current water demand projections, the DRPE has established a programme for water mobilisation works until 2020, and proposes a management plan in order to meet the increasing pressure on the already limited water resources of the Moulouya Basin. The principal objectives of this management plan are:
-  the maximum mobilisation of water resources in order to meet the demand for potable, industrial and irrigation water;
-  the protection of the Mohamed V Dam against silting;
-  and the capping of the maximum flood probability at 6,000 m3 /s. The resource-needs balance scenarios consider two options: a plan without a new dam, and a plan with the construction of dams of local interest and dams of regional interest. The first scenario results in a deficit of approximately 200 Mm3/year, whereas the scenario with construction of dams results in a surplus of approximately 30 Mm3/year with a use rate of the lower Moulouya of 81%. In any case, the water demand forecasts in the Moulouya Master Plan (1992) are somewhat outdated. The report from 1997 on the water sector study carried out by the Ministry of Public Works updated the data, integrating the most recent forecasts.

It appears, therefore, that despite the construction of projected dams, the water resources available in2020 will not be able to fully meet the water demand. Furthermore, the deficit obtained of 176 Mm3/year is an underestimation, as it does not take into account the reduction of water resources due to global warming, estimated in Morocco at approximately 15% by 2020. (MATUHE, 2001). On the environmental level, the analysis of the impacts caused by the construction of the various dams presented in the Master Plan considers:
-  negative effects only with regard to the surface areas and habitats that would be flooded by the dams. The ecosystems and populations at risk downriver of the dams were not considered at all in the environmental impact study; and
-  the probable positive consequences on the quality of water of the Moulouya and its tributaries, based on a foreseen sustained low water mark that could dilute any possible pollution. Now, with its SIBE status and the MedWetCoast project diagnosis, the downriver area could be expected to be included as a whole in the management strategies for natural resources in general, andfor water resources in particular in the basin. ...

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Web Team

P.S. Source : IUCN website