An alternative approach to conventional seepage meters: Buoy‐type seepage meter

Abstract

AbstractWe propose a new type of seepage meter to allow sequential measurements of submarine groundwater discharge (SGD) rate and SGD‐driven chemical flux at a point on seawater and groundwater interface. The system works on the basis of Δh, the difference in head between groundwater and seawater at groundwater–seawater interface, and uses a vertical cylinder fixed to a buoy to derive groundwater outflow corresponding to Δh from the seepage meter chamber to the vertical cylinder. Laboratory tank tests showed that volumetric flow rate (Q) from the buoy‐type seepage meter (BSM) compared very well with conventional seepage meter (CSM). The linear relationship between Q measurements with the two methods is also statistically significant (R2 = 0.976). Two sample t‐test reveals that there is not a significant difference between means of Q measurements with the two methods. R2 values of linear regressions between volumetric flow rate (Q) and Δh are 0.993 with the BSM, and 0.972 with the CSM. Field tests with the BSM at Bangdu Bay of Jeju Island, Korea also show linear relationship (R2 = 0.86) between SGD flux and Δh, and SGD flux and SGD‐derived chemical fluxes are inversely related to tides. Both results of laboratory and field tests support that the proposed seepage meter can be an alternative to the conventional seepage meters for measuring SGD flux, and that it can be used to monitor temporal variations of SGD flux and SGD‐driven chemical fluxes simultaneously.