A TOP SPECIFIED BOUNDARY-LAYER (TSBL) APPROXIMATION APPROACH FOR THE SIMULATION OF GROUNDWATER CONTAMINATION PROCESSES

This paper presents improvements in the ''classical boundary layer'' ( CBL) approximation method to obtain simple but robust initial characte rization of aquifer contamination processes. Contaminants are consider ed to penetrate into the groundwater through the free surface of the a quifer. The improved method developed in this study is termed the ''to p specified boundary layer'' (TSBL) approach. It involves the specific ation of the contaminant concentration at the top of the contaminated ''region of interest'' (ROI), which is simulated as a boundary layer. The TSBL modification significantly improves the ability of the bounda ry layer method to predict the development of concentration profiles o ver both space and time. The TSBL method can be useful for the simulat ion of cases in which the contaminant concentration is prescribed at t he aquifer's free surface as well as for cases in which the contaminan t mass flux is prescribed at the surface.