ABSTRACT

The interaction of an industrial river and the groundwater aquifer in Florida are modeled by time series-, flow modeling- and particle tracking methods. The major purpose of the modeling effort is to delineate the possible contamination corridor in the aquifer as may be caused by the infiltration of polluted water from the industrial river. The interrelations of precipitation, river discharge and groundwater data series are first analyzed by methods of structural time series, in order to quantify the interdependence of the groundwater table and river gauge heights, and thus tp statistically examine the hydraulic possibility of aquifer contamination. The interaction of the stream and the groundwater is simulated by the USGSMODFLOW model. For the calibration, simulated water tables are compared with the historical records of monitoring wells in the adjacent aquifer. Lateral ‘stagnant’ points of the water flow based on the transient simulation arc connected to delineate the maximal contamination corridor along both sides of the stream. In addition, particle tracking simulations with varying water sources and forcing conditions are conducted to compute the dynamic movements of water particles out along the river banks. The modeling results show that lateral migration of contaminants close to the industrial discharge point might be up to several thousands feet in cross-river direction during times when the normally gaining (effluent) stream becomes sectionally a losing (influent) stream. The last situation occurs especially during multiyear-long time spans with less-than-normal precipitation which, for Florida, happens during times between major El Niño occurrences; i.e. during La Niña years.