Numerical Groundwater Modelling as an Effective Tool for Management of the Deep Aquifer at the Dakhla Bay (South of Morocco)

Abstract

Fossil groundwater is used for water supply and irrigation in some arid regions where the replenishment of groundwater by precipitation is low. Numerical modelling is a helpful tool in the assessment of groundwater resources and analysis of future exploitation scenarios. To quantify the groundwater resources of the Dakhla area in the southern Sahara, Morocco, the present study assesses the groundwater resources management of the Paleogene aquifer. Groundwater withdrawals have increased in this area, resulting in a disturbance of the aquifer’s natural equilibrium, and the large-scale and ongoing depletion of this critical water reserve. Negative impacts, such as a decline in water levels, have been experienced. The methodology includes application of numerical groundwater modelling in steady and transient states under different measures and abstraction scenarios. The numerical simulation model developed was applied to assess the responses of the Paleogene aquifer water level under different pumping scenarios during the next 10 years. Groundwater management scenarios are evaluated to find an optimal management solution to satisfy future needs. To cope with the unfavourable state of the water resources of Dakhla in the coming years, a groundwater contract was developed to save the groundwater resources and not compromise the socio-economic development of the region, particularly agricultural development. This contract includes technical, organizational and financial measures. They were discussed in workshops with all stakeholders to identify good management alternatives in the Dakhla area in south of Morocco.