Saltwater Transport under the Influence of Sea-Level Rise in Coastal Multilayered Aquifers

Abstract

Guo, Q.; Zhang, Y.; Zhou, Z., and Zhao, Y., 2020. Saltwater transport under the influence of sea-level rise in coastal multilayered aquifers. Journal of Coastal Research, 36(5), 1040–1049. Coconut Creek (Florida), ISSN 0749-0208.The dynamic behavior of groundwater flow and salt transport in coastal multilayered aquifers is affected by sea-level rise (SLR). Two sets of laboratory experiments were completed that took into account SLR (seawater rising from 85 to 105 cm for scenario 1 and inland head decreasing from 100 to 80 cm for scenario 2). Groundwater flow and salt transport in the multilayered aquifers were observed during the experiment. SEAWAT software was used to validate the processes of seawater transport in the coastal multilayered aquifer under the influence of SLR. The hydrogeological parameters were identified by fitting the observed values of groundwater level and salinity in the model. The influences of aquifer heterogeneity, SLR, and boundary condition on solute mixing of saltwater and freshwater were described. Results showed that the transient toe penetration xtoe and area of the seawater wedge increased initially and then tended to stabilize as the seawater level increased in each stage of both scenarios. The spreading rate of the seawater wedge during the process of releasing water in scenario 2 was faster than that of storing water in scenario 1, although the difference between sea level and inland boundary head was the same in the two scenarios. Sensitivity analysis indicated that the estimated parameters were reasonable. Moreover, the variation of the seawater wedge could not be reproduced well when the hydraulic conductivities and saltwater density of the upper and lower layers were increased or decreased. The analysis provided insights into how SLR and inland water head influence seawater intrusion rate and area.