14
Impacts of Beach Placer Mineral
Mining in the Shallow Coastal
Aquifers of Southern Tamil Nadu
Coast, India
S. Selvakumar and N. Chandrasekar
Abstract
Groundwater in the coastal area is relatively
vulnerable to the contamination by seawater
intrusion, which makes it unsuitable for
drinking or irrigation. This study was carried
out along the coastal aquifer of southern Tamil
Nadu, India. To access the impact of mining,
the coast was divided into three sites, namely
(i) non-placer sand area, (ii) active mining
area and (iii) inland dune area. The non-placer
sand area is assumed to be undisturbed and is
considered as reference site. The inland dunes
sand area is the area with no active mining but
within the impact of the mining activity.
Hydrogeochemical and groundwater table
characteristics of shallow coastal aquifer system in the mining and non-mining area were
investigated to identify the salinization process. The Na/Cl ratio, correlation matrix and
ionic relationship between major ions showed
a marked increase in salinization in the active
mining area and nearby wells. The reverse ion
exchange and seawater intrusion control the
groundwater chemistry along the active mining aquifers. The spatial visualization of
electrical conductivity, salinity, chloride and
groundwater quality index map (GWQI) that
reflects active mining areas are exhibiting
poor water quality and are comparatively low
in non-placer mining areas. Gibb’s diagram
representing evaporation is the dominant process more than the rock water interaction and
precipitation. The groundwater level fluctuation in both inland dune and non-placer sand
area aquifers blocks a little variation due to
lack of rainfall, irrespective of volumes of
water recharge and over pumping of groundwater for irrigational purposes. In the active
mining region, the groundwater level shows
high fluctuation of ±3 to ±5 m below the
ground level. Depth profile study indicates the
highly depleted groundwater level in the
active mining region that has induced higher
EC value and salinity. The process might,
therefore, be related to the saltwater encroachments. Tidal induces changes in water level in
the Karamaniyar river estuary and near the
active mining wells around 1.03 m and the
Vembar river estuary water level increased in
the wells around 0.68 m.
Keywords
Groundwater salinity Á Seawater intrusion Á
Beach placer mining Á Southern Tamil nadu
coast
S. Selvakumar Á N. Chandrasekar (&)
Centre for Geotechnology, Manonamaniam
Sundaranar University, Tirunelveli 627 012, India
e-mail: profncsekar@gmail.com
© Springer Nature Switzerland AG 2021
B. W. Pandey and S. Anand (eds.), Water Science and Sustainability, Sustainable Development Goals Series,
https://doi.org/10.1007/978-3-030-57488-8_14
183
Impacts of Beach Placer Mineral
Mining in the Shallow Coastal
Aquifers of Southern Tamil Nadu
Coast, India
S. Selvakumar and N. Chandrasekar
Abstract
Groundwater in the coastal area is relatively
vulnerable to the contamination by seawater
intrusion, which makes it unsuitable for
drinking or irrigation. This study was carried
out along the coastal aquifer of southern Tamil
Nadu, India. To access the impact of mining,
the coast was divided into three sites, namely
(i) non-placer sand area, (ii) active mining
area and (iii) inland dune area. The non-placer
sand area is assumed to be undisturbed and is
considered as reference site. The inland dunes
sand area is the area with no active mining but
within the impact of the mining activity.
Hydrogeochemical and groundwater table
characteristics of shallow coastal aquifer system in the mining and non-mining area were
investigated to identify the salinization process. The Na/Cl ratio, correlation matrix and
ionic relationship between major ions showed
a marked increase in salinization in the active
mining area and nearby wells. The reverse ion
exchange and seawater intrusion control the
groundwater chemistry along the active mining aquifers. The spatial visualization of
electrical conductivity, salinity, chloride and
groundwater quality index map (GWQI) that
reflects active mining areas are exhibiting
poor water quality and are comparatively low
in non-placer mining areas. Gibb’s diagram
representing evaporation is the dominant process more than the rock water interaction and
precipitation. The groundwater level fluctuation in both inland dune and non-placer sand
area aquifers blocks a little variation due to
lack of rainfall, irrespective of volumes of
water recharge and over pumping of groundwater for irrigational purposes. In the active
mining region, the groundwater level shows
high fluctuation of ±3 to ±5 m below the
ground level. Depth profile study indicates the
highly depleted groundwater level in the
active mining region that has induced higher
EC value and salinity. The process might,
therefore, be related to the saltwater encroachments. Tidal induces changes in water level in
the Karamaniyar river estuary and near the
active mining wells around 1.03 m and the
Vembar river estuary water level increased in
the wells around 0.68 m.
Keywords
Groundwater salinity Á Seawater intrusion Á
Beach placer mining Á Southern Tamil nadu
coast
S. Selvakumar Á N. Chandrasekar (&)
Centre for Geotechnology, Manonamaniam
Sundaranar University, Tirunelveli 627 012, India
e-mail: profncsekar@gmail.com
© Springer Nature Switzerland AG 2021
B. W. Pandey and S. Anand (eds.), Water Science and Sustainability, Sustainable Development Goals Series,
https://doi.org/10.1007/978-3-030-57488-8_14
183