Seasonal freeze-thaw effects on submarine groundwater discharge in coastal unconfined aquifers

Submarine groundwater discharge (SGD) can deliver land-sourced chemicals to coastal waters, influencing coastal biogeochemistry and ecosystems. In cold regions, submarine groundwater discharge commonly occurs under seasonal freeze-thaw conditions, but how freeze-thaw processes affect SGD in coastal unconfined aquifers remains unclear. This study examines the fluctuation of water efflux in coastal aquifers under seasonal freeze-thaw conditions, based on a two-dimensional conceptual model. Simulations were conducted using a modified SUTRA-MS model that incorporates freeze-thaw processes into variably saturated, density-dependent groundwater flow coupled with salt and heat transport. The response of frozen layer thickness and SGD to seasonal freeze-thaw will be discussed here in detail.