HGS Research Highlight - An exploration of coupled surface-subsurface solute transport in a fully integrated catchment model

This post features a study recently completed by LIggett et al., 2015 who used HGS to investigate the inclusion of both flow and solute transport in a fully integrated 3D catchment model, where field measurements of both flow and solute transport were available.

An exploration of coupled surface-subsurface solute transport in a fully integrated catchment model

Authors: Jessica E. Liggett, Daniel Partington, Sven Frei, Adrian D. Werner, Craig T. Simmons, and Jan. H. Fleckenstein

Coupling surface and subsurface water flow is one of the strengths of fully integrated hydrological codes such as HydroGeoSphere (HGS). Following the coupling of surface-subsurface water flow, is coupling of surface-subsurface solute transport, although this subject has received less attention in the literature. Previous studies have focused on coupled surface-subsurface solute transport at small scales, with simple geometric domains, and have not utilised many different field data sources. The purpose of this study was to use HGS to demonstrate the inclusion of both flow and solute transport in a fully integrated 3D catchment model, where field measurements of both water flow and solute transport (as dissolved organic carbon) were available for the Lehstenbach catchment in southeast Germany. As with water flow, solute transport between the surface and subsurface is sensitive to the numerical implementation and model parameters that govern the surface-subsurface connection. We performed a sensitivity analysis to examine the effects of different solute transport conditions at the surface-subsurface boundary (i.e. advective solute exchange only, advection plus diffusion, and advection plus full hydrodynamic dispersion), as well as different subsurface dispersivities, on modelled transport results. The results show that while including solutes in an integrated model can be beneficial for gauging model behaviour, there are challenges in constraining the non-uniqueness of the surface-subsurface solute transport solution and in determining the influence of dispersion across the surface-subsurface interface. This work highlights the importance of the combination of field and modelling investigations when considering surface-subsurface solute transport.   The HGS Research Highlight Series features recent publications and projects completed using HGS. If you have recently completed a project using HGS and would like to see it featured here please contact sberg@aquanty.com.

Coupling surface and subsurface water flow is one of the strengths of fully integrated hydrological codes such as HydroGeoSphere (HGS). Following the coupling of surface-subsurface water flow, is coupling of surface-subsurface solute transport, although this subject has received less attention in the literature. Previous studies have focused on coupled surface-subsurface solute transport at small scales, with simple geometric domains, and have not utilised many different field data sources. The purpose of this study was to use HGS to demonstrate the inclusion of both flow and solute transport in a fully integrated 3D catchment model, where field measurements of both water flow and solute transport (as dissolved organic carbon) were available for the Lehstenbach catchment in southeast Germany. As with water flow, solute transport between the surface and subsurface is sensitive to the numerical implementation and model parameters that govern the surface-subsurface connection. We performed a sensitivity analysis to examine the effects of different solute transport conditions at the surface-subsurface boundary (i.e. advective solute exchange only, advection plus diffusion, and advection plus full hydrodynamic dispersion), as well as different subsurface dispersivities, on modelled transport results. The results show that while including solutes in an integrated model can be beneficial for gauging model behaviour, there are challenges in constraining the non-uniqueness of the surface-subsurface solute transport solution and in determining the influence of dispersion across the surface-subsurface interface. This work highlights the importance of the combination of field and modelling investigations when considering surface-subsurface solute transport.

 

The HGS Research Highlight Series features recent publications and projects completed using HGS. If you have recently completed a project using HGS and would like to see it featured here please contact sberg@aquanty.com.