Subsurface flow and transport in tidal wetlands: Marsh plain equations

Subsurface flow and salinity patterns in a tidal marsh plain determine the character and health of the wetland ecosystem. The presence of a flow field with both saturated and unsaturated regions requires that the governing eq uations and the associated equations of state transition smoothly between t he two regions. The fluid density in the marsh plain is not constant; it re sponds to changes in both pressure head and salinity. These considerations lead to the development of the marsh plain equations, the coupled field equ ations for subsurface flow and salinity transport in the continuous saturat ed/unsaturated flow domain of a tidal wetland.