MATHEMATICAL MODELING OF POLLUTANT MIGRATION IN UNSATURATED FRACTURED FORMATIONS

A MATHEMATICAL MODEL, USING THE DUAL-POROSITY CONCEPT, IS BEING INVESTIGATED FOR THE TRANSPORT OF CONTAMINANTS IN UNSATURATED FRACTURED ROCKS. THE FORMATION IS VISUALIZED AS A COMPOSITE OF TWO OVERLAPPING CONTINUA: THE POROUS MATRIX AND THE FRACTURES. THESE TWO MEDIA COMMUNICATE VIA INTERPOROSITY EXCHANGE MECHANISMS THAT ARE FUNCTIONS OF THE DIFFERENCE IN THE SOLUTE CONCENTRATION (FOR THE SPECIE TRANSPORT PROBLEM) OR THE PRESSURE (FOR THE FLUID FLOW PROBLEM) IN THE TWO MEDIA. RESEARCHERS ARE EXAMINING VARIOUS MATHEMATICAL REPRESENTATIONS OF THESE INTERMEDIA EXCHANGE TERMS. SPECIAL ATTENTION IS PAID TO RADIOACTIVE WASTE. THE MODEL IS THE FIRST STEP TOWARD DEVELOPING A COMPREHENSIVE COMPUTER MODEL FOR ASSESSING THE MOVEMENT OF POLLUTANTS IN UNSATURATED FRACTURED FORMATIONS. THE OBJECTIVE IS THE ESTABLISHMENT OF A FIELD-CONSISTENT MATHEMATICAL MODEL FOR THE TRANSPORT PROCESS IN A VARIABLY SATURATED FRACTURED ROCK. APPROXIMATE ANALYTICAL SOLUTIONS USING PARAMETER PERTURBATION, ASYMPTOTIC ANALYSES, AND TRANSFORM TECHNIQUES ARE OBTAINED IN ORDER TO EXAMINE KEY CHARACTERISTICS OF CONTAMINANT MIGRATION IN UNSATURATED FRACTURED FORMATIONS.