In arid to semi-arid countries water scarcity on a national level is seemingly contradicted by the local occurrence of sometimes large amounts of domestic wastewater. Consequently, in many countries this wastewater is considered as an additional source of water, particularly for irrigation purposes. The government of Egypt is planning to use wastewater in land reclamation in many areas on the Eastern and Western fringes of the Nile Valley and Delta.
A preliminary survey on the effects of wastewater irrigation was carried out by the Research Institute for Groundwater (RIGW) in the Gabal el Asfar area (Greater Cairo) in 1990-1991. A general framework of reuse of sewage effluent for irrigation in Egypt was discussed. The hydrogeological setting of the Gabal el Asfar area, the groundwater flow system and the thickness of the unsaturated zone were described. The impact on groundwater quality from sewage effluent irrigation has been assessed and the migration of pollution was evaluated.
The main objective of the present study is to analyze and explain changes in groundwater quality between 1991 and 1994. The study is executed within the framework of the Environmental Management Groundwater Resources project.