Utilizing multichannel electrical resistivity methods to examine the contributions of submarine groundwater discharges

Abstract

Submarine groundwater discharge is the main way to transfer land-based sources to the ocean. To verify the in situ monitoring capability of the multichannel electrical resistivity method for groundwater discharge in the coastal zone during tidal processes, in situ monitoring was carried out in different aquifers of Shilaoren Bay in September 2015 and May 2017. The electrodes were placed on the seabed, and the collection array was dipole-dipole. The monitoring results show that during tidal processes, seawater intrusion and submarine groundwater discharges in different sedimentary layers have different spatial and temporal evolution characteristics and they can clearly be reflected in time-series resistivity profiles. The percentage difference change in resistivity can be used to define the main groundwater discharge areas. Based on the theory of balance of salinity, the average discharge rate for different periods can also be estimated. Through monitoring, we find that the main discharge area is in the middle and lower parts of the intertidal zone and that the average discharge rate per unit area is 0.86 m³/h, which is the same as the actual values. From the monitoring results, we find that the multichannel electrical resistivity method has good in situ monitoring capability.

Keywords:

• Submarine groundwater discharge
• multichannel electrical resistivity method
• in situ monitoring
• discharge estimation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the by the NationalNatural Science Foundation of China (41772307, 41977234) and Fundamental Research Funds for the Central Universities(201962005).