A Coupled Groundwater–Surface Water Modeling Framework for Simulating Transition Zone Processes

Abstract

There is an identified need for fully representing groundwater-surface water transition zone (i.e., the sediment zone that connects groundwater and surface water) processes in modeling fate and transport of contaminants to assist with management of contaminated sediments. Most existing groundwater and surface water fate and transport models are not dynamically linked and do not consider transition zone processes such as bioturbation and deposition and erosion of sediments. An interface module is developed herein to holistically simulate the fate and transport by coupling two commonly used models, Environmental Fluid Dynamics Code (EFDC) and SEAWAT, to simulate surface water and groundwater hydrodynamics, while providing an enhanced representation of the processes in the transition zone. Transition zone and surface water contaminant processes were represented through an enhanced version of the EFDC model, AQFATE. AQFATE also includes SEDZLJ, a state-of-the-science surface water sediment transport model. The modeling framework was tested on a published test problem and applied to evaluate field-scale two- and three-dimensional contaminant transport. The model accurately simulated concentrations of salinity from a published test case. For the field-scale applications, the model showed excellent mass balance closure for the transition zone and provided accurate simulations of all transition zone processes represented in the modeling framework. The model predictions for the two-dimensional field case were consistent with site-specific observations of contaminant migration. This modeling framework represents advancement in the simulation of transition zone processes and can help inform risk assessment at sites where contaminant sources from upland areas have the potential to impact sediments and surface water.

A Review on the Research Advances in Groundwater–Surface Water Interaction with an Overview of the Phenomenon

“…Understanding the various aspects of the transition zone, including the hydrological, geochemical, ecological, and sociological factors, is crucial for effective water resource management and the preservation of ecosystems. Many researchers have studied the interaction in this zone and tried to analyze the effect of varying transition zone characteristics on the interaction [71][72][73].…”

Integrated Environmental Modelling Framework for Cumulative Effects Assessment

“…Although the existing ready-to-use integrated subsurface and surface water and solute transport models such as HGS and MIKE SHE are capable of simulating groundwater-surface water interactions, they do not appear to provide a full representation of sediment/benthic processes. Mugunthan et al (2017) developed an interface module that holistically simulates fate and transport by dynamically coupling two commonly used models, AQFATE and SEAWAT, to simulate surface water and groundwater hydrodynamics, while providing an enhanced representation of the processes in the transition zone. AQFATE is an enhanced version of the EFDC model (Connolly et al, 2000).…”

Model‐supported decision‐making at a contaminated sediment site: Post‐audit and site closure

“…The model framework (i.e., the FORTRAN computer code) used at the Site, AQFATE (Connolly et al, 2000; Mugunthan et al, 2016), is an enhanced version of the Environmental Fluid Dynamics Code (EFDC; Hamrick, 1992) linked to the Water Quality Analysis Simulation for Toxics (WASTOX; Connolly & Winfield, 1984) model. AQFATE has been applied at many contaminated sediment sites.…”