A Simultaneous Solution Approach for Coupled Surface and Subsurface Flow Modeling

Abstract

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.