The effects and implication of tides and rainfall on the circulation of water within salt marsh sediments’

The response of the water table of an intertidal salt marsh in NW England has been investigated. During neap tides, water seeps upward from the underlying sand-silt-clay interface. This effect continues as the marsh is overtopped during spring tides but is then dwarfed by penetration of water downward from the surface. Under “typical conditions” the delay between high water in the river and maximum apparent water level for the marsh becomes less as the spring-tide cycle maximum is approached. Lags also appear smaller during summer, probably mainly due to desiccation cracks. Precipitation effects are only important when rainfall is significant in quantity and coincides with low water during