Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Geology

Wadi El Raiyan as a great depression in the Faiyum Governorate has been utilized for wastewater storage since 1973. The depression contains two artificial lakes (Upper and Lower) connected together through a narrow channel. The widespread of pollution in the drainage water with the shrinkage in the lower lake's size poses a possible hazard to the aquatic and wildlife systems. Chemical analysis (major and trace elements), and microbiological analyses were made. The extensive evaporation of water augments the salt content, heavy metals, pesticides and other pollutants in Wadi El Raiyan Lakes. An evaporation model was applied on the input sources to the two Wadi El Raiyan lakes to expect the main factors controlling the geochemical composition of lakes{u2019} water. Change detection technique was used to identify and to map the major land cover types as well as to quantify the magnitude; rates and nature of the land cover changes. In the cultivated land drainage, the major-ion chemistry is generally influenced by chemical weathering of rocks and minerals with anthropogenic inputs. In the depression lakes, the water chemistry generally exhibits an evaporation-dependent evolutionary trend that is further modified by cation exchange and precipitation of carbonate minerals. The lower lake lost about 50% of its area between 2001 and 2014. Two scenarios may be expected for the hazardous effects on the lower lake. The first one is maintaining the same rate of deterioration until complete dryness of the lower lake in few years, while the second one could be anticipated if action plans were enforced by the government to increase the recharge of the lower lake once again

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