Source characteristics and contaminant plume evolution

This study investigated how features of mass distribution within a source a rea control the pattern of contaminant plume evolution. A series of numeric al trials was conducted which simulated contaminant migration in a three-di mensional saturated porous media with multiple source patches representing zones of contamination. Results showed that the extent of mixing near the s ource was greatly affected by both advection and dispersive mixing processe s. The factors affecting the concentration distribution in the dissolved pl ume were size and distribution of source patches, dispersivity values, and the ratio of total patch area to the source area. The influence of dispersi ve mixing increased as the size of source patches decreased. However, dispe rsion was less important when patches were clustered or the ratio of total patch area to the source area increased. The variations in concentration va lues near the source, which were caused by differences in sizes and distrib ution of patches, diminished as the contaminant traveled further from the s ource. This result implies that detailed information on source characterist ics generally would not be required beyond a certain travel distance. The e xception in this regard is the ratio of total patch area to the source area , i.e., a zero-difference point. However, the location of this zero-differe nce point cannot be predicted easily because the location was affected by s everal source characteristics.