A Fully Coupled Depth-Integrated Model for Surface Water and Groundwater Flow

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Li Yuanyi, Yuan Dekui, Jianhua Tao

Thursday 2 july 2015

9:45 - 10:00h at Oceania (level 0)

Themes: (T) Hydro-environment, (ST) Ecohydraulics and ecohydrology, (T) Water engineering, (ST) Computational methods

Parallel session: 10E. Engineering - Computational

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Inter-tidal regions are characterized by strong dynamic interactions between surface water and groundwater flows with the porous media including sediments and gravels presenting in this region. The previous models used to these areas often computed the two parts of the flow separately and consider the interaction between the two parts using a interface matched method. To overcome the restriction of interface, which is unphysical, This paper presents a fully coupled model to simulate surface water and groundwater flows in coastal areas. Governing equations for surface water flow and groundwater flow are derived using a control volume approach, in which the water exchange and interaction between the two kinds of flows are taken into account. Equations of groundwater include the convection term and a term not only considering the linear drag caused by porous media, but also turbulence drag, quadratic to averaged velocity in porous media. Then the two sets of governing equations are combined and integrated from the bottom of the groundwater to the free surface, with velocity profiles in the cross-sections in the two sub-regions being taken into consideration. Using this fully coupled model, the surface water flow and groundwater flow can be calculated simultaneously within the same numerical scheme and the interaction between these two types of flows is naturally taken into consideration. No other effort is needed to link the flows in the two sub-regions. The model was validated against several benchmark tests and the results show that the model could well simulate the combined surface water and groundwater flows in coastal regions and no computational instability occurring in the simulations.