Estimation of Salt Balance in Salt-Affected Ecosystems in Arid Areas, Case Study: El Fayoum Depression, Egypt.

Document Type : Research Studies

Authors

1 Hydrology Department, Desert Research Center, Cairo, Egypt

2 Hydrology Department., Desert Research Center., Cairo., Egypt.

Abstract

El Fayoum depression is a semi-closed depression located about 100 Km southwest of Cairo-Egypt It occupies an area of about 1200 Km2. Due to the complex geological and hydrological conditions of that area, water logging problem and soil salinization affect great parts of the cultivated areas. The geological conditions are manifested in the rich content of clay in the Quaternary aquifer, the relative small aquifer thickness and the dominance of faulted and fractured limestone at the base and on the peripheries. On the other hand, the hydrological conditions include the occurrence of a thick net of irrigation system and presence of huge surface water bodies; e.g. Qarun lake and Wadi El Rayan lakes. Moreover, the groundwater depths vary from few centimeters below ground surface to 7.51 m which reflect a critical soil salt-affected problem. The present paper throws light on the salt balance of the groundwater regime. The estimation of the input and output components is carried out based on the field measurements during 2006. The estimated mean annual salt influx reaches 2.05 million tons. The Output component includes the salt efflux through the drainage network, subsurface groundwater flow and the salinity losses due to plant uptake. The estimated annual mean value of salt efflux from these three components reaches 3.8 million tons. The average annual storage component is estimated to be -1.75 million tons. The estimation of salt balance shows that the groundwater or/and soil water receive an excess of annual salt content of 1.75 million tons due to leaching process of evaporites and clay lenses during its flow from the upstream till it reaches the downstream area (Qarun Lake). Mitigation of imbalanced salt load through minimizing the losses from drainage network and using low consumed cop pattern is highly recommended.

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