The Dakhla Basin belongs to the Nubian Aquifer System. The thickness of the aquifer in the Dakhla area is between 900 and 1600 m, in the Kharga area 300–800 m and at Tarfawi at about 500 m. Most of the groundwater of the aquifer was enriched in pluvialPluvial times. Today, groundwater in southwestern Egypt is considered fossil and nonrenewable. The groundwater in the oases is confined and is found on two layers at 100–350 m and 400–2000 m depth. In prehistory, the water must have flowed from several artesian wells. Due to water consumption in the last 5000 years, the groundwater level dropped for several meters. Due to the lowering of groundwater, many arable fields are watered sparingly, which is leading to soil salinization. According to the United States Salinity Laboratory Staff (United States Salinity Laboratory in Diagnosis and improvement of saline and alkali soils. US Department Agriculture Handbook, 1954), the quality of groundwater of the aquifer is classified as “medium” to “highly saline.” Through millennia of irrigation in the area of the oases, a higher groundwater layer and small lakes (evaporation pondsEvaporation ponds) have formed.