Updating the Coupling Algorithm between HYDRUS and MODFLOW in the HYDRUS Package for MODFLOW

Sahila Beegum; Jiří Šimůnek; Adam Szymkiewicz; K Sudheer; Indumathi Nambi

doi:10.2136/vzj2018.02.0034

Updating the Coupling Algorithm between HYDRUS and MODFLOW in the HYDRUS Package for MODFLOW

Abstract

The HYDRUS-based flow package for MODFLOW (the HPM or the HYDRUS package) is an existing unsaturated zone flow package for MODFLOW. In MODFLOW with the HPM, the groundwater modeling domain is discretized into regular grids that can be combined into multiple zones based on similarities in soil hydrology, topographical characteristics, and the depth to the groundwater. Each of these zones is assigned one unsaturated soil profile (the HPM profile). In this model, after every MODFLOW time step, the flux at the bottom of the HPM profile is given as an input recharge flux to MODFLOW. MODFLOW simulates groundwater flow, and the water table depth at the end of the MODFLOW time step is assigned as the bottom boundary condition in the HPM profile. The current coupling algorithm assumes that the groundwater table in the HPM profile remains constant throughout the entire MODFLOW time step. This results in unrealistic sudden inflow and/or outflow fluxes at the bottom of the HPM profile after every time step. The objective of this study was to develop a methodology to eliminate the error in the determination of the recharge flux at the bottom of the HPM profile. This was achieved by updating or modifying the pressure head profile in the HPM profile after every MODFLOW time step. The effectiveness and the applicability of the new coupling algorithm were evaluated using different case studies. The new coupling algorithm is effective in eliminating unrealistic sudden variations in the bottom flux in the HPM profiles.

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DOI:: Digital Object Identifier (open in new tab) 10.2136/vzj2018.02.0034
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Category:: Articles
Type:: artykuł w czasopiśmie wyróżnionym w JCR
Published in:: VADOSE ZONE JOURNAL no. 17, edition 1, pages 1 - 8,
ISSN: 1539-1663
Language:: English
Publication year:: 2018
Bibliographic description:: Beegum S., Šimůnek J., Szymkiewicz A., Sudheer K., Nambi I.: Updating the Coupling Algorithm between HYDRUS and MODFLOW in the HYDRUS Package for MODFLOW// VADOSE ZONE JOURNAL. -Vol. 17, iss. 1 (2018), s.1-8
DOI:: Digital Object Identifier (open in new tab) 10.2136/vzj2018.02.0034
Verified by:: Gdańsk University of Technology