Experimental and numerical investigation of saltwater intrusion dynamics in flux-controlled groundwater systems

Abstract

Sea level rise and reduction of groundwater fluxes due to changes in rainfall patterns are the two major climate change–induced hydrological variables that can severely affect saltwater intrusion in coastal aquifers. In this study we use a combination of laboratory experiments and numerical simulations to study the impacts of changes in one of these climate change–induced hydrological variables, groundwater flux, on saltwater intrusion process. We have completed experiments in a laboratory-scale model to study the changes in two types of groundwater fluxes—areal recharge flux and regional flux. The experimental results were modeled using the numerical code SEAWAT. The transient data sets reported in this study are useful benchmarks for testing numerical models that employ flux-type boundary conditions. Also, based on the experimental observations, we hypothesize that when the fluxes are perturbed, it would require relatively less time for a salt wedge to recede from an aquifer when compared to the time required to advance into the aquifer. This rather counterintuitive hypothesis implies that saltwater intrusion and receding processes are asymmetric and the timescales associated with these processes will be different. We use a combination of laboratory and numerical experiments to test this hypothesis and use the resulting data set to explain the reason for the difference in intrusion rates.