Selective withdrawal from recharged aquifers
1987
Fattah, Q.N. (Baghdad Univ., Baghdad (Iraq). Coll. of Engineering) | Mansour, M.J. (Scientific Research Council, Baghdad (Iraq). Agriculture and Water Resources Research Centre, P.O. Box 2416)
This investigation concerns the problem of selective withdrawal from unconfined aquifers with stratification in water quality caused by recharge. To examine the hydraulics of this phenomenon, a physical laboratory model was constructed to simulate the essential elements of the physical problem. A homogeneous, isotropic, porous media was utilized in the model with a suction pipe representing a well at its center. Water quality stratification was achieved through the establishment of two layers of water with a maximum difference in salt concentration of 0.2% by weight. Two sets of tests were carried out, first with the inlet of the well in the recharged water layer and second with the inlet of the well in the ambient water layer. A constant water level condition was maintained in the porous media to ascertian steady well discharges throughout the tests. For each of the situations tested, two sets of curves were plotted. The first vertical distributions of electrical conductivity in the aquifer were prepared. The second set presents curves of electrical conductivity versus discharge of the withdrawn water from the well. Dimensional analysis carried out to determine the parameters that govern the hydraulic of this phenomenon. Relationships were developed between the densimetric froude No. and the dimensionless thickness of the mixing zone for the two cases considered in this investigation. As a result of the analysis, it was shown that as the concentration of the withdrawn water increases, there is an increase in the critical velocity for both of the situations tested in this work
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