A Simultaneous Solution Approach for Coupled Surface and Subsurface Flow Modeling

Coupled hydrologic modeling of surface and subsurface systems has gained a lot of popularity in the last two decades. Channel flow and groundwater flow models are coupled to obtain a better understanding of these hydrologic pathways in a watershed. In general, this coupling process is done in an iterative fashion until sufficient convergence is achieved for common parameters linking these different domains. In this study, we propose a new solution methodology based on the simultaneous solution of channel and groundwater flow. The method is based on the idea of solving a single global matrix at once rather than solving separate matrices for each flow domain and iteratively improving the solution. This new solution technique is tested by coupling a one-dimensional stream flow model that uses the complete form of the St. Venant equation with a two-dimensional vertically-averaged groundwater flow model. The proposed simultaneous solution approach provides a more efficient solution for this coupled flow problem and is superior to the approximate solution obtained through an iterative approach.This report is based on the work conducted in the Multimedia Environmental Simulations Laboratory at the School of Civil and Environmental Engineering, Georgia Institute of Technology. Partial financial support for this work was provided by the Georgia Sea Grant of the National Sea Grant College Program and the Georgia Institute of Technology. Authors are grateful for the continued support of the two institutions in the area of environmental modeling studies. Computational services of this work were provided by the Multimedia Environmental Simulations Laboratory facilities