Analytical and Numerical Groundwater Flow Solutions for the FEMME-Modeling Environment

Mustafa El-Rawy,Getachew Mohammed,Kerst Buis,Christian Anibas,Okke Batelaan,Wouter Zijl,Ali Salem

doi:10.3390/hydrology7020027

Abstract

Simple analytical and numerical solutions for confined and unconfined groundwater-surface water interaction in one and two dimensions were developed in the STRIVE package (stream river ecosystem) as part of FEMME (flexible environment for mathematically modelling the environment). Analytical and numerical solutions for interaction between one-dimensional confined and unconfined aquifers and rivers were used to study the effects of a 0.5 m sudden rise in the river water level for 24 h. Furthermore, a two-dimensional groundwater model for an unconfined aquifer was developed and coupled with a one-dimensional hydrodynamic model. This model was applied on a 1 km long reach of the Aa River, Belgium. Two different types of river water level conditions were tested. A MODFLOW model was set up for these different types of water level condition in order to compare the results with the models implemented in STRIVE. The results of the analytical solutions for confined and unconfined aquifers were in good agreement with the numerical results. The results of the two-dimensional groundwater model developed in STRIVE also showed that there is a good agreement with the MODFLOW solutions. It is concluded that the facilities of STRIVE can be used to improve the understanding of groundwater-surface water interaction and to couple the groundwater module with other modules developed for STRIVE. With these new models STRIVE proves to be a powerful example as a development and testing environment for integrated water modeling.

Highlights

There is a need to evaluate groundwater-surface water (GW-SW) interaction for water and ecosystem management
We present the modeling methodologies (FEMME, STRIVE package, hydrodynamic model, analytical and numerical solutions) as well as applications and comparison between analytical and numerical solutions, coupling with a hydrodynamic model, and comparison between STRIVE and MODFLOW
The implemented one-dimensional analytical and numerical solutions for groundwater heads and discharges in unconfined or confined aquifers are compared as a function of time and distance

Summary

Introduction

There is a need to evaluate groundwater-surface water (GW-SW) interaction for water and ecosystem management. This is essential because linkages and feedback between groundwater. Hydrology 2020, 7, 27 and surface water systems affect both the quantity and quality of available water required by humans and ecosystems [1,2,3,4]. The research topic of GW-SW interaction has gained importance in the last two decades, because of its role in conjunctive use, riparian zone management, and ecohydrology. Understanding the interaction between groundwater and surface water can be important in the determination of migration pathways for contaminants [5]. The hydraulics of groundwater interaction with adjoining streams, canals, and drains is an important aspect of many hydrogeologic systems. Examples are the support of groundwater discharge to stream flow, bank storage attenuation of flood waves, and how groundwater discharge to streams lowers water tables maintains favorable root-zone salinity levels and prevents water logging of soil [6]

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Conclusion