Transport of Contamination under the Influence of Sea Level Rise in Coastal Heterogeneous Aquifer

Abstract

This paper provided for the first time an experimental study on the influence of sea level rise on transport of contamination in the heterogeneous unconfined aquifer of the coastal zone. The experiments were conducted using the tank, considering the difference between sea level and inland head 1 cm for Case 1 and 2 cm for Case 2. Observed data were validated using the numerical model, which matched well with the toe length of seawater wedge and the shape of the contaminant plume. The results showed that the observed and simulated values of Cl− concentration at the sampling points increased sharply at the initial time, and then they increased slowly and tended to be stable. The seawater wedge migrated inland with time under the effects of the hydraulic gradient toward the inland and the density difference between saltwater and freshwater. The steady state length of the 50% isoline of the seawater wedge was 167 cm in Case 2, which was larger than that of Case 1. The maximum area of plume in Case 2 was 0.13 m2, larger than that in Case 1, which indicated that the velocity of diffusion of the contaminant plume increased as the sea level increased. As the velocity of diffusion increased, the time for pollutant migration to the intersection between seawater and freshwater became shorter. The maximum area and vertical depth of pollutant plume were sensitive to the hydraulic conductivity, dispersivity, and contamination concentration. The infiltration depth and range of the contaminant plume in the heterogeneous aquifer were greater than those in the homogeneous aquifer of the actual beach.

Case Study of Contaminant Transport Using Lagrangian Particle Tracking Model in a Macro-Tidal Estuary

“…This is further supported by the alignment of our study with the investigations into Lake Erie's harmful algal blooms; these investigations highlight the utility of both Lagrangian and Eulerian models in forecasting ecosystem responses and the potential for hybrid approaches that can enhance future models [19]. The research integrates advanced modeling techniques and insights from various studies, highlighting the significant role of geomorphological features and their interaction with hydrodynamic processes [20][21][22]. The analysis of 'Creek' and 'No Creek' cases provides new insights into the protective role of tidal creeks in material transport within estuarine systems.…”

Contamination Transport in the Coastal Unconfined Aquifer under the Influences of Seawater Intrusion and Inland Freshwater Recharge—Laboratory Experiments and Numerical Simulations

“…The hydraulic conductivity, dispersivity and concentration of contamination were important parameters for solute transport in the heterogeneous aquifer [ 56 ]. Therefore, the sensitivities of saltwater contamination transported in the aquifer to the model parameters were analyzed in the scenario of landward hydraulic gradient.…”

“…The interval between each two sampling ports was 20 cm. More details about the experiment device can be found in Guo et al [ 56 ].…”

“…The interval between each two sampling ports was 20 cm. More details about the experiment device can be found in Guo et al [56]. There were ten pressure taps arranging at the bottom of the sand tank, which were used to measure the groundwater level variation in the aquifer.…”

CrAssphage as an indicator of groundwater-borne pollution in coastal ecosystems

“…These freshwater zones in coastal aquifers often serve as important water supplies but are threatened by rising sea levels (Sawyer et al 2016, Michael et al 2017, McKenzie et al 2021. Changing coastal groundwater dynamics will also influence contaminant transport processes and negatively impact potable coastal groundwater supplies and the marine ecosystems receiving groundwater discharge (LeMonte et al 2017, Guo et al 2020). Submarine groundwater discharge (SGD) is defined as the flow of fresh and circulated saline groundwater (e.g., LeRoux et al 2021) from the seabed to the coastal ocean, regardless of fluid composition or driving force .…”