Effect of cut-off walls on submarine groundwater discharge in non-isothermal conditions
Temperature could change the migration characteristics of coastal groundwater.However,research on groundwater discharge processes under the influences of cut-off walls has been limited to isothermal conditions.This study built a two-dimensional numerical model coupling groundwater flow and salt transport in non-isothermal conditions at the site scale to investigate the impact of cut-off walls on groundwater discharge processes,considering the thermal effect.We focused on the dynamic characteristics of submarine groundwater discharge in non-isothermal conditions which are common in reality.This research quantitatively assessed the influence of seawater temperature on groundwater discharge flux(Q)and relative discharge flux(Q').The results indicate that,under high-temperature seawater conditions,the timescale for Q'to reach equilibrium is significantly reduced.Specifically,higher freshwater temperatures and lower seawater temperatures could result in a greater Q'.However,when the seawater temperature exceeded the groundwater temperature by 15℃,reverse circulation is more likely to develop in the saltwater zone,which accelerates groundwater circulation and increases the total groundwater discharge into the sea,resulting in a corresponding rise in the Q'value.This study is significant for cut-off wall structure optimization and coastal groundwater sustainable utilization.
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