NUMERICAL-SOLUTION OF THE DIFFERENTIAL-EQUATION FOR MOVING FRONT DISPERSION

It is shown that the differential equations presented by Strack (1992, Water Resour. Res., 28(11): 2973-2980) for moving front dispersion ar e hyperbolic, and general expressions for the velocity of the front an d the concentration at the front are presented. The method of solution known as the method of characteristics (not to be confused with the m ethod known in groundwater transport modeling as the method of charact eristics) is presented for solving the system of equations for moving front dispersion. Jumps are shown to be allowable across the character istics, and the jump conditions are presented. The numerical method is outlined for the case of a pulse of concentration at a point of an in finitely long streamline. The numerical solution is validated by compa rison with an exact solution.