Thesis (Ph.D.) - Cairo University - Faculty of Engineering - Department of Civil Engineering

An elevated groundwater table and salinization are prevailing problems confronting the irrigated lands in arid and semi-arid regions. The lower euphrates basin in Syria have suffered from waterlogging and salinity problems since eighties because of the inappropriate climatic conditions, poor soil drainage in addition to using the traditional methods in irrigation. Visual MODFLOW (2010) was used to simulate the groundwater flow and salt transport in one of the lower euphrates valley. The model geometry was built using RockWork program. HYDRUS -1-D program was used to determine the recharge and its concentration to the groundwater. Three processes were simulated in HYDRUS; water flow, salt transport and root water uptake. The study showed that the current drainage situation is inadequate and the water table continues to rise. Three scenarios were proposed to reduce the groundwater table. The first scenario proposed to add (50) wells with discharge (50) m3/hr. While in the second scenario, the discharge from the same proposed wells in the first scenario was increased to 70 m3/hr. In the third scenario, the number of wells was reduced to 45 wells with the same discharge as in the second scenario. The sites of these wells were chosen based on multi criteria decision making. The proposed scenarios resulted in acceptable drawdown over the study area, especially in the middle area where the minimum depth to groundwater table occurs. These results ensure the efficiency of the applied scenarios

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