14.1 Introduction
Salinization of potable water resources is an
emerging issue in India and it may damage
agricultural productivity and health. Continued
groundwater withdrawals, compounded by a
decrease in groundwater recharge, can trigger the
seawater/freshwater interface to move inland
resulting in additional salinization of the coastal
aquifer (Blanco et al. 2013). The seawater
intrusion phenomenon can be attributed to a
variety of conditions like gentle coastal hydraulic
gradients, tidal and estuarine activity, excessive
and heavy withdrawals of groundwater from
coastal plain aquifers, depletion of groundwater
level, low infiltration and local hydrogeological
conditions. Sea-level rise associated with climate
change is a potentially significant process that is
expected to play a role in seawater intrusion.
Where sea-level fluctuations are retained within
the intertidal zone (i.e., coastal barriers are not
overtopped), their influence on seawater intrusion is more ambiguous (Werner et al. 2013).
The coastline of southern Tamil Nadu has
witnessed largest beach placer mineral extractions for more than several decades. One of the
most serious and subtle but ignored negative
consequences of sand mining is on groundwater
recharge and quality as a result of the extraction
process. For instance, some of the characteristics
that make sand a valuable resource also makes it
very good aquifer and recharge material. Sand
mining within an aquifer recharge will increase
the vulnerability of the aquifer in the coastal
region, because it decreases the distance between
the water level, land surface and sea level. Impact
of mining on the land environment gets reflected
in land-use pattern of the respective areas,
because the land gets more exposed to erosion by
losing its green cover or by getting disturbed
otherwise due to mining (excavation, overburden
dumping etc.) and related activities. Water
resources get damaged, soils get contaminated,
and part or total of flora and fauna get lost. Air
and water get polluted and more damages go on
proceeding in accelerated rates and the cumulative effects push the land toward degradation.
The coastal sand excavation in this region has
actually penetrated into the shallow aquifer,
leading to a direct access to groundwater.
Despite, there have been no studies on the extent
of coastal placer mining operation or of the
impact in shallow coastal aquifers. Yet, minimization of the negative effects of sand mining
requires a detailed understanding of the nature
and sources of the impact groundwater resources.
The aim of this study is therefore, on shallow
coastal aquifer of the coastal areas, to provide
proper resource management and utilization.
Salinization occurrence has been recognized by
groundwater quality measurements, depth to
groundwater level measurements and tidal level
fluctuation. Avoiding saltwater intrusion is particularly important because once contamination
has occurred it is often very difficult and
expensive to remediate (Dominico and Schwartz
1990). Hence it is important to realize that seawater intrusion is a dynamic not a static process
that depends on the periodic changes in the
recharge and discharge balance of the aquifer.
Any influence direct, or interaction, on the
aquifer in water balance affects the position and
movement of the seawater interface and chemistry of the groundwater (Elena Gimanezforcada
2010). Seawater intrusion into coastal fresh
groundwater aquifers depends on surface and
underground topography, hydraulic characteristics of aquifer, change in precipitation volume,
groundwater flow patterns, infiltration rate, tidal
and estuarine activity, overexploitation of
groundwater and anthropogenic contamination of
soil and water (Mondal et al. 2011; Singaraja
et al. 2016). In the context of current status, a
detailed study to determine the hydrogeology of
the coastal mining area and the nature as well as
extent of saltwater intrusion is a prerequisite in
the prevention of further saltwater intrusion and
is urgently required. Further, it is predicted that
water abstraction will increase by 50% in the
region, as population growth and development
drive result in upward demand by the year 2025.
In recent years, the availability of water and its
quality have emerged as the major constraints to
economic development and quality of life.
184
S. Selvakumar and N. Chandrasekar
Salinization of potable water resources is an
emerging issue in India and it may damage
agricultural productivity and health. Continued
groundwater withdrawals, compounded by a
decrease in groundwater recharge, can trigger the
seawater/freshwater interface to move inland
resulting in additional salinization of the coastal
aquifer (Blanco et al. 2013). The seawater
intrusion phenomenon can be attributed to a
variety of conditions like gentle coastal hydraulic
gradients, tidal and estuarine activity, excessive
and heavy withdrawals of groundwater from
coastal plain aquifers, depletion of groundwater
level, low infiltration and local hydrogeological
conditions. Sea-level rise associated with climate
change is a potentially significant process that is
expected to play a role in seawater intrusion.
Where sea-level fluctuations are retained within
the intertidal zone (i.e., coastal barriers are not
overtopped), their influence on seawater intrusion is more ambiguous (Werner et al. 2013).
The coastline of southern Tamil Nadu has
witnessed largest beach placer mineral extractions for more than several decades. One of the
most serious and subtle but ignored negative
consequences of sand mining is on groundwater
recharge and quality as a result of the extraction
process. For instance, some of the characteristics
that make sand a valuable resource also makes it
very good aquifer and recharge material. Sand
mining within an aquifer recharge will increase
the vulnerability of the aquifer in the coastal
region, because it decreases the distance between
the water level, land surface and sea level. Impact
of mining on the land environment gets reflected
in land-use pattern of the respective areas,
because the land gets more exposed to erosion by
losing its green cover or by getting disturbed
otherwise due to mining (excavation, overburden
dumping etc.) and related activities. Water
resources get damaged, soils get contaminated,
and part or total of flora and fauna get lost. Air
and water get polluted and more damages go on
proceeding in accelerated rates and the cumulative effects push the land toward degradation.
The coastal sand excavation in this region has
actually penetrated into the shallow aquifer,
leading to a direct access to groundwater.
Despite, there have been no studies on the extent
of coastal placer mining operation or of the
impact in shallow coastal aquifers. Yet, minimization of the negative effects of sand mining
requires a detailed understanding of the nature
and sources of the impact groundwater resources.
The aim of this study is therefore, on shallow
coastal aquifer of the coastal areas, to provide
proper resource management and utilization.
Salinization occurrence has been recognized by
groundwater quality measurements, depth to
groundwater level measurements and tidal level
fluctuation. Avoiding saltwater intrusion is particularly important because once contamination
has occurred it is often very difficult and
expensive to remediate (Dominico and Schwartz
1990). Hence it is important to realize that seawater intrusion is a dynamic not a static process
that depends on the periodic changes in the
recharge and discharge balance of the aquifer.
Any influence direct, or interaction, on the
aquifer in water balance affects the position and
movement of the seawater interface and chemistry of the groundwater (Elena Gimanezforcada
2010). Seawater intrusion into coastal fresh
groundwater aquifers depends on surface and
underground topography, hydraulic characteristics of aquifer, change in precipitation volume,
groundwater flow patterns, infiltration rate, tidal
and estuarine activity, overexploitation of
groundwater and anthropogenic contamination of
soil and water (Mondal et al. 2011; Singaraja
et al. 2016). In the context of current status, a
detailed study to determine the hydrogeology of
the coastal mining area and the nature as well as
extent of saltwater intrusion is a prerequisite in
the prevention of further saltwater intrusion and
is urgently required. Further, it is predicted that
water abstraction will increase by 50% in the
region, as population growth and development
drive result in upward demand by the year 2025.
In recent years, the availability of water and its
quality have emerged as the major constraints to
economic development and quality of life.
184
S. Selvakumar and N. Chandrasekar