ASSESSMENT OF GROUND WATER CONTAMINATION FROM AN INDUSTRIAL RIVER BY TIME SERIES-, FLOW MODELING- AND PARTICLE TRACKING METHODS

摘要

The interaction of an industrial river and the groundwater aquifer in Florida are modeled by time scries-, flow modeling- and particle (racking methods, The major piuposc of the mcxleling ellbil is to delineate (lie possible contamination corridor in (lie aquifer as may be caused by llic infiltration cf 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 to statistically examine the hydraulic possibility of aquifer contamination. The interaction of the stream and the groundwater is simulated by tr?eUSGSMODFLOWmodel.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 are 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 thedynamicmovementsofwatei'particlesoutandalongtheriver 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 Niflo occurrences; i.e. during La Nina years.