Modelling of tide induced pore water flow and solute transport in a salt marsh

Coastal salt marshes are the important intertidal ecosystems at the land-ocean interface.The investigation of the complex flows and the associated solute transport in marsh soils is made in order to improve our understanding of these wetland systems,particularly the relation to the important hypotheses in the marsh ecology:the nutrient outwelling and the plant zonation.In this paper,we modify the SUTRA code to simulate the complex pore water flows and the associated solute transport in marsh soils.We simulate the pore water flow and the associated solute transport in a salt marsh based on an imaginary creek section.The results show that the pore water flow and the associated solute exchange near the tidal creek are more intensive than in the inner marsh,which prevents pore water solute near the creek from concentrating or accumulating.During the ebb tide,the pore water flow near the tidal creek is both vertical and horizontal,while it is primarily horizontal far from the creek. The optimal aeration condition is also found occurring near the tidal creek.These results are consistent with the observation that the salt marsh plants often grow better near tidal creeks than in the inner areas.