Dewatering of an unvegetated muddy tidal flat during exposure—Desiccation or drainage?

An unvegetated muddy tidal flat was sampled to determine the changes in surface pore water content and salinity during exposure. Local evaporation accounted for 61% of the upper intertidal surface salinity, with evaporation rates increasing salinity as high as 2.2‰ per hour. In contrast, only 37% of the decrease in pore water content was attributed to evaporative processes. This suggests that drainage (a combination of porosity and permeability) controlled the water content rather than local evaporative conditions.