Simulation of oil spill infiltration and redistribution in a shallow aquifer
Simulations of oil spill infiltration and redistribution in a shallow aquifer were conducted in this work to quantify their effects on groundwater. Results showed that flow of oil spills can be adequately described by infiltration and redistribution patterns within the domain. Without the influence of rainfall, the contaminant plume pervaded the water table within one year of the spill through the influence of dissolution, diffusive and convective mechanisms. The plume advanced in the domain first by domain wall trailing in a manner suggestive of oil-wetting characteristics followed by bulk plume movement. Simultaneous infiltration with rainfall increased the rate of contaminant penetration and aided the plume front further into the domain. Without influence of rain, uncontaminated water can be found at a depth beyond 30 m from the spill surface at 30 years after the spill, while the possibility of clean water with influence of rainfall, at the same period of time, became remote even up to the bottom of the aquifer as the rainfall drives the plume into the furthest depth though, this is accompanied by cleaner water body at the upper portion of the aquifer. It was found that the impacts of contaminants on aquifer water are influenced by contaminant components, wettability of the aquifer, annual rates of rainfall, boundary conditions of the source and possibly size of the domain. Findings in this report point to the needs for quicker clean up exercises and identification of multi-approach procedures for different spill scenarios.
Key words: Simulation, oil spills, infiltration, redistribution, Niger Delta.