ABSTRACT
A non-invasive method called Visual Scaling Technique (VST) was applied to determine dispersion of injected dye solution in estuarine beach-sand. It comprises site-survey, solute-injection, plume-recovery and data recording processes. This is uniquely different from previous studies where the injection position of the solute is different from the monitoring point. Full 2-D plume-images of the contaminated area were captured using digital camera and the color intensity converted to concentration profiles by calibration. The geometric impressions of the plumes were found to vary with location detailing groundwater flow directions, hence contaminant pathways. The movement of pollutants is due to impact of tides, which uniquely differs in comparison to contaminant transport in aquifers. Dispersion coefficient was found to increase with travel distance even in such relatively uniform beach-sand. The findings confirm that the vadose zone of the study field is vulnerable, and contaminant transport is feasible through tidally driven surfacewater and groundwater exchange.
