Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. T...Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. This aquifer covers an area of 250 Km2, and represents an essential water resource for Laayoun city and the periphery regions. It is heavily exploited for water supply, agriculture and industry. The freshwater-saltwater interface is affected by groundwater extraction by public supplies, irrigation wells, and domestic wells in the coastal of this aquifer. The position of the interface is controlled by several factors: these include precipitation, recharge rate, dryness, evapotranspiration, hydraulic conductivity and hydraulic head. Landward migration of the interface freshwater-saltwater often results in a significant decrease in the water resources available for coastal communities. The volume pumped by public for irrigation and the domestic usage in 2010-2011 is estimated 2.5 Mm3/year, and in 2015 about 2.91 Mm3/year only for domestic usages. The objectives of this work are to model the groundwater flow and saltwater intrusion in the coastal aquifer of Fum Al Wad, by SEAWAT-2000 program which coupled both the version of MODFLOW-2000 and MT3DMS. They are designed to simulate variable-density groundwater flow and solute transport in three dimensions. The model is calibrated for hydraulic conductivity, specific yield, porosity, and recharge rate as well as dispersivity coefficient. The result of simulation of the hydrodynamic model during the period of 1986-2015 has revealed a piezometric drawdown with 2.3 m approximately at the level of the pumping zone. Furthermore, this piezometric depression is caused by excessive pumping of the various uses of water and its corresponding that has resulted in the migration of the saltwater intrusion into freshwater with 4.3 km approximately. The simulations result for scenarios 2020 and 2030 of Fum Al Wad aquifer showed a vertical decrease of the piezometric head (about 2.5 m) in 2030, but the saltwater intrusion has advanced diagonally to reach 4.7 km under the freshwater of groundwater of this aquifer.展开更多
The Charf El Akab aquifer has a surface area of 17 km2 and is located about 20 km southwest of the Tangier city, it circulates in the Miocene sandy basin of the same name and comprises two layers, one high and the oth...The Charf El Akab aquifer has a surface area of 17 km2 and is located about 20 km southwest of the Tangier city, it circulates in the Miocene sandy basin of the same name and comprises two layers, one high and the other low, these two are separated in some places by an airtight impenetrable sand-marly formation. The requirements for water whether potable or industrial, in the Tangier-Asilah region are expected to amplify in order to support the increasing demand prompted by the economical development, population growth as well as the heightened threat of scarcity related to climate change. Currently, the water supply of this region is ensured mostly by the two dams: Ibn Battouta and “April 9, 1947”. However, this aquifer plays the role of an easily usable emergency reservoir, in case of an extra water supply in rush hour or in the event where current service works of the cities of Tangier and Asilah are unavailable. Nevertheless, water resources are still vulnerable because of the existence of abandoned quarries in the area. Therefore, the protection of this aquifer against any source of pollution is the purpose of this work. The lower water layer is the only one that can be exploited by the ONEE (National Office for Electricity and Drinking Water), due to the fact that it has a better quality and very good hydrodynamic characteristics. The most important thing about this work is the establishment of an intrinsic vulnerability map to the pollution by the DRASTIC method, by exploiting of the calibrated hydrodynamical model results. In the same context of protection, a guesstimate of the close protection perimeter of 72.76 ha was acquired, using a new numerical modeling approach by the “Arcfem” software under the ArcMap environment.展开更多
文摘Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. This aquifer covers an area of 250 Km2, and represents an essential water resource for Laayoun city and the periphery regions. It is heavily exploited for water supply, agriculture and industry. The freshwater-saltwater interface is affected by groundwater extraction by public supplies, irrigation wells, and domestic wells in the coastal of this aquifer. The position of the interface is controlled by several factors: these include precipitation, recharge rate, dryness, evapotranspiration, hydraulic conductivity and hydraulic head. Landward migration of the interface freshwater-saltwater often results in a significant decrease in the water resources available for coastal communities. The volume pumped by public for irrigation and the domestic usage in 2010-2011 is estimated 2.5 Mm3/year, and in 2015 about 2.91 Mm3/year only for domestic usages. The objectives of this work are to model the groundwater flow and saltwater intrusion in the coastal aquifer of Fum Al Wad, by SEAWAT-2000 program which coupled both the version of MODFLOW-2000 and MT3DMS. They are designed to simulate variable-density groundwater flow and solute transport in three dimensions. The model is calibrated for hydraulic conductivity, specific yield, porosity, and recharge rate as well as dispersivity coefficient. The result of simulation of the hydrodynamic model during the period of 1986-2015 has revealed a piezometric drawdown with 2.3 m approximately at the level of the pumping zone. Furthermore, this piezometric depression is caused by excessive pumping of the various uses of water and its corresponding that has resulted in the migration of the saltwater intrusion into freshwater with 4.3 km approximately. The simulations result for scenarios 2020 and 2030 of Fum Al Wad aquifer showed a vertical decrease of the piezometric head (about 2.5 m) in 2030, but the saltwater intrusion has advanced diagonally to reach 4.7 km under the freshwater of groundwater of this aquifer.
文摘The Charf El Akab aquifer has a surface area of 17 km2 and is located about 20 km southwest of the Tangier city, it circulates in the Miocene sandy basin of the same name and comprises two layers, one high and the other low, these two are separated in some places by an airtight impenetrable sand-marly formation. The requirements for water whether potable or industrial, in the Tangier-Asilah region are expected to amplify in order to support the increasing demand prompted by the economical development, population growth as well as the heightened threat of scarcity related to climate change. Currently, the water supply of this region is ensured mostly by the two dams: Ibn Battouta and “April 9, 1947”. However, this aquifer plays the role of an easily usable emergency reservoir, in case of an extra water supply in rush hour or in the event where current service works of the cities of Tangier and Asilah are unavailable. Nevertheless, water resources are still vulnerable because of the existence of abandoned quarries in the area. Therefore, the protection of this aquifer against any source of pollution is the purpose of this work. The lower water layer is the only one that can be exploited by the ONEE (National Office for Electricity and Drinking Water), due to the fact that it has a better quality and very good hydrodynamic characteristics. The most important thing about this work is the establishment of an intrinsic vulnerability map to the pollution by the DRASTIC method, by exploiting of the calibrated hydrodynamical model results. In the same context of protection, a guesstimate of the close protection perimeter of 72.76 ha was acquired, using a new numerical modeling approach by the “Arcfem” software under the ArcMap environment.
