شبكة التخطيط العمراني بسم الله الرحمن الرحيم
للكاتب :
Y. R. Fares
The British University in Egypt, Faculty of Engineering
Sherouk City, Cairo-Ismailia Road, Cairo, Egypt
Abstract
A numerical model capable of predicting the dispersion of pollutant discharges along a
homogeneous aquifer is presented. The advection-dispersion equation (ADE) is utilised in
predicting the concentration levels for cases of continuous and instantaneous release modes.
The Crank-Nicholson equation is employed in the presented model and the solution is carried
out using the implicit Gauss-Seidel method with over- and under-relaxation coefficients,
depending on the state of convergence. The performance of the numerical scheme has
improved significantly by removing the zero- and first-order truncation errors in the ADE
with a reaction term. The computed concentration profiles are compared with measured
values for cases of non-reactive (tracer) and reactive (organic) solutes with continuous
injection in homogeneous isotropic soils. The analysis of results has shown that for the case of
non-reactive solutes, reliable simulations are produced. While for the case of solutes
undergoing adsorption, accurate concentrations can be predicted by adjusting the influent pore
water velocity by using a retardation factor, which is suitable for aquifers with low organic
carbon content and undergoing hydrophobic partitioning. Finally, the mechanisms relating to
the soil/pore water interactions, such as ion exchange, chemi-sorption and physic-sorption,
can be embraced in the model for simulating dispersive reactive solutes within the saturated
zone.