Flow‐Through Stream Modeling with MODFLOW and MT3D: Certainties and Limitations

Abstract

This paper aims to assess MODFLOW and MT3D capabilities for simulating the spread of contaminants from a river exhibiting an unusual relationship with an alluvial aquifer, with the groundwater head higher than the river head on one side and lower on the other (flow‐through stream). A series of simulation tests is conducted using a simple hypothetical model so as to characterize and quantify these limitations. Simulation results show that the expected contaminant spread could be achieved with a specific configuration composed of two sets of parameters: (1) modeled object parameters (hydraulic groundwater gradient, hydraulic conductivity values of aquifer and streambed), and (2) modeling parameters (vertical discretization of aquifer, horizontal refinement of stream modeled with River [RIV] package). The influence of these various parameters on simulation results is investigated, and potential complications and errors are identified. Contaminant spread from stream to aquifer is not always reproduced by MT3D due to the RIV package's inability to simulate lateral exchange fluxes between stream and aquifer. This paper identifies the need for a MODFLOW streamflow package allowing lateral stream‐aquifer interactions and streamflow routine calculations. Such developments could be of particular interest for modeling contaminated flow‐through streams.

A Novel Simulation-Optimization Model Built by FloPy: Pollutant Traceability in a Chemical Park in China

“…However, this software also limits the research space for most users [11]. The great portability of most numerical groundwater flow simulation software means that the user can only interact within the scope of the features it provides [12,13]. Diversification and crossover between the numerical groundwater flow simulation and other fields still requires a return to programming [14].…”