Evidence for submarine groundwater discharge on the Southwestern shelf of Taiwan

Model for Predicting the Transport and Dispersal of Contaminants Incoming with Submarine Groundwater: Case Study for the Southwestern Taiwan Coastal Zone

“…In the vicinity of the SG seepage (marked by solid squared in Figure 1), CTD measurements revealed salinity inversions on profiles in the 2 m bottom layer (Figure 2(b)), where the magnitude of the salinity drop reached 0.06 psu. For such salinity drop, the SGD rate, as was estimated by [21], should be in range between 0.1 and 1 gm -2 •s -1 . The estimation was based on the advection-diffusion balance of salinity in the water column affected groundwater inflow,…”

“…The deviation of vertical velocity and magnitude of the SGD rate, obtained by [21], is associated with variations of and S  H  estimated from field experiments. Besides uncertainties in estimation of and S  H  the rate, Q, depends on vertical diffusivity, K z , which was chosen from general assumptions.…”

“…To detect shallow SGDs, quantify their rate and influence on the local hydrology as well as define the content of contaminants, the joint oceanographic observations were conducted by Taiwanese and the Russian scientific groups in February and October 2009 on the Pingtung shelf [21]. Figure 1 schematically depicts the transections of the polygon where hydrophysical and hydrochemical observations have been conducted.…”

“…They showed that the semidiurnal, M 2 , constituent was the major one in energy spectra of tidal oscillation. Thus, for the first order approximation, we can simplify tidal forcing by a use of the dominant constituent M 2 only and, for tuning the circulation module, we utilized current velocity measurements conducted by [21] near by the SGD well. We applied a radiation condition based on the long gravity-wave speed, to determine the boundary elevation and a gravity-wave radiation condition to specify the normal component of the depth-averaged current at the model open boundaries.…”

“…As an example of a nonconservative contaminant we will take nitrate (NO 3 ) that, as recognized now, is the major contaminant of SG. Recalling measurements by [21] discussed above, we can set the initial concentration of nitrate as C 0 = 0.48 mg•L -1 ), The reduction of nitrate due to denitrification and other reactions can be described by a first-order degradation process with an exponential decrease in concentration in the cell-volume…”