Measurement of submarine groundwater discharge using diverse methods in Coleroon Estuary, Tamil Nadu, India

Abstract

Submarine groundwater discharge (SGD) is described as submarine inflow of fresh and brackish groundwater from land into the sea. The release of sewages from point and non-point source pollutants from industries, agricultural and domestic activities gets discharged through groundwater to ocean creating natural disparity like decreasing flora fauna and phytoplankton blooms. Hence, to quantify fluxes of SGD in coastal regions is important. Quantification of SGD was attempted in Coleroon estuary, India, using three dissimilar methods like water budget, Darcy law and manual seepage meter. Three seepage meters were installed at two prominent litho units (alluvium and fluvio marine) at a distance of (0-14.7 km) away from Bay of Bengal. The water budget and Darcy law-quantified submarine seepage at a rate of 6.9 × 10 6 and 3.2 × 10 3 to 308.3 × 10 3 m 3 year −1 , respectively, and the seepage meter quantified seepage rate of 0.7024 m h −1 at an average. Larger seepage variations were isolated from three different techniques and the seepage rates were found to be influenced by hydrogeological characteristics of the litho units and distance from the coast.

Estimating groundwater inputs from Sankarabarani River Basin, South India to the Bay of Bengal evaluated by Radium (226Ra) and nutrient fluxes

“…The river forms estuary at the configuring point with a mean depth of 5.0 m with semidiurnal tides ranging in heights from 0.32 to 1.31 m generating substantial inflow of saline water into the river [17]. The sediment transport due to the impact of wave, tide, river or wind energy is estimated as 237,000 m 3 yr -1 towards north [39].…”

“…Methodologies available for measuring groundwater fluxes and associated nutrient exchanges to the bay like application of Darcy's law [17][18][19][20] seepage meters, thermal infrared imagery, flow and density dependent modeling and application of geochemical tracers [21][22][23][24][25][26][27][28][29][30].…”

“…Due to increase in population, anthropogenic related activities (major industries like paper, alcoholic beverages, chemical, pharmaceutical, agricultural and tourist activities) has altered the material instabilities in the river and adjoining regions due to direct discharge of nutrient, metal and toxic elemental fluxes resulting in ecological imbalance [37]. Previous studies [17,38] has attempted for groundwater fluxes using radon mass balance approach and radon progeny calculations. But attempts relating radium and nutrient fluxes are gloomy.…”

Marine Electromagnetic Imaging and Volumetric Estimation of Freshwater Plumes Offshore Hawai'i

“…The fresh portion of SGD is critical, as it potentially buffers ocean acidification with groundwater alkalinity (Cyronak et al., 2013; Slomp & Van Cappellen, 2004). While coastal SGD has been documented globally at various geological settings (Kim & Kim, 2011; Knee et al., 2016; Paldor et al., 2020; Prakash et al., 2018; Stieglitz, 2005), reports on deep offshore SGD sources (disconnected from coastal SGD, usually appear at water depths >50 m) are scarce but of potential importance. Fresh SGD is commonly associated with oceanographic, hydrogeological, and environmental processes that affect chemical weathering, ocean eutrophication, and climate change by emanating solutes and gases to the ocean (e.g., Moore, 2010; Kim & Kim, 2011; Taniguchi et al., 2019; Luijendijk et al., 2020).…”

Integrated geophysical and geochemical assessment of submarine groundwater discharge in coastal terrace of Tiruchendur, Southern India

“…Therefore, aquifer characteristic study is essential for SGD flux estimation. Prakash et al (2018), Manivannan and Elango et al (2019), Babu et al (2009Babu et al ( , 2021). An estimation of freshwater discharge using electrical resistivity methods of 2D ERT and magnetotelluric method.…”