Quantifying Seepage‐Face Evaporation and Its Effects on Groundwater Flow and Solute Transport in Small‐Slope Tidal Flat

Abstract Large‐scale seepage faces occur on tidal flats with gentle slope, which are widely distributed worldwide. Evaporation on these seepage faces, leading to salt retention and accumulation, may significantly impact the density‐dependent groundwater flow beneath the tidal flats. However, due to nonlinear complexities of the groundwater flow and solute transport on seepage faces, explicit boundary conditions and numerical models to quantify these processes are lacking. In this study, we present both mathematical and numerical models to quantify these processes. Compared to the results of our previous study, this paper shows that seepage‐face evaporation can (a) significantly increase the groundwater salinity in the upper intertidal zone, and form multiple groundwater circulation cells in the intertidal zone, (b) cause the disappearance of multiple seepage‐faces and reduce the spatial extent of seepage faces notably, (c) and intensify the groundwater and salt exchange as well as the seawater‐groundwater circulation through the intertidal zone.