conductivity values also increased. The change
might therefore be related to the saltwater
encroachment into the aquifer. Further, the
drastic changes on water level in the active
mining region are observed in all seasons, which
may be influenced by the transmissivity in dunal
aquifers, and the ocean tides in the mining sites
located nearer to the backshore has enhanced the
effect of water table variation (Kim et al. 2008).
Groundwater extraction is the primary cause
of seawater intrusion (Tibbott 1992). In the
coastal regions, successive pumping will also
cause seawater intrusion, consequently leading to
the possibility of polluting the groundwater and
corroding subsurface structures. As freshwater
resources are depleted, results show an accompanying reduction in the height of the freshwater
table, and the saltwater interface begins an
upward and inland encroachment. It is important
to have a detailed understanding of the spatial
distribution of the coastal groundwater level and
temporal resolution of the processes that control
changes in water table height, and therefore it is
essential to monitor groundwater levels continuously throughout the coastal zone in mining sites.
14.1.5 Tidal Level Fluctuation
Tidal activity can often induce a fluctuating water
table as well as infiltration of surface water into
sediments, forming a surficial mixing zone with
groundwater discharging from the adjacent
aquifer (Robinson et al. 1998; Ataie-Ashtiani
et al. 1999; Zhou et al. 2006). The groundwater
behavior in an unconfined aquifer with a mild
sloping face in response to a tide is affected by
two factors that do not exist in a confined aquifer.
These factors are the infiltration of saltwater from
the top of the beach slope into the aquifer at high
tide and tidal pumping with a free water table.
The latter effect is intensive by a mild sloping
beach and the existence of a seepage-face at the
sea boundary of the groundwater.
The tidal level and groundwater water level
fluctuation measurements are studied in Vembar
river estuaries, Karamaniyar river estuaries and
dug wells near to coastal mining (Fig. 14.9).
14.1.5.1 Vembar River Estuary
The experimental setup was deployed in two
selected sites along the Vembar estuary (from 8
am to 5 pm in a day). The minute wise fluctuation was recorded using an automatic data logger
device. This device has the capability to monitor
the pressure difference and the temperature
change. The results reveal that high tide exhibits
around 8 am and 5 pm and low tide is noticed
around 2 pm in the estuarine mouth monitoring
well. This fluctuation is barely because of the
medium of water transport. The sediment texture
of this site is 99% sand, which allows seawater to
easily pass through. However, in other sites (site
no. 2, 3, 4) the fluctuations vary with respect to
high tide and the level becomes almost stable.
This may be due to the presence of clay as it is a
poor medium for water transmittance. The hourly
tidal fluctuations are shown in Fig. 14.10. The
distribution of temperature in the study area is
dependent on the temperature of the incoming
river and seawater, the mixing processes and on
the exchange of heat through the surface. The
effect of temperature is to increase the density
difference between river and seawater. The study
area experiences the tidal-induced water table
motion in the phreatic aquifer of the shoreline.
The water table range varies between 4.25 and
3.38 mbgl during 2011–2013. In the monitoring
well the water table is observed as 2.78 mbgl.
This reveals that the tide-induced change in water
level is around 0.68 m (Simon Peter et al. 2014).
14.1.5.2 Karamaniyar River Estuary
In the Karamaniyar river estuary, it is seen that
the distribution is controlled mostly by the local
weather conditions. Surface temperature of the
water chiefly depends on the incoming solar
radiation; the estuary being a shallow one, the
distribution appeared to be dominated by the
diurnal effect rather than tidal effect. The study
area experiences the tidal-induced water table
motion in the phreatic aquifer of the coastal
196
S. Selvakumar and N. Chandrasekar
might therefore be related to the saltwater
encroachment into the aquifer. Further, the
drastic changes on water level in the active
mining region are observed in all seasons, which
may be influenced by the transmissivity in dunal
aquifers, and the ocean tides in the mining sites
located nearer to the backshore has enhanced the
effect of water table variation (Kim et al. 2008).
Groundwater extraction is the primary cause
of seawater intrusion (Tibbott 1992). In the
coastal regions, successive pumping will also
cause seawater intrusion, consequently leading to
the possibility of polluting the groundwater and
corroding subsurface structures. As freshwater
resources are depleted, results show an accompanying reduction in the height of the freshwater
table, and the saltwater interface begins an
upward and inland encroachment. It is important
to have a detailed understanding of the spatial
distribution of the coastal groundwater level and
temporal resolution of the processes that control
changes in water table height, and therefore it is
essential to monitor groundwater levels continuously throughout the coastal zone in mining sites.
14.1.5 Tidal Level Fluctuation
Tidal activity can often induce a fluctuating water
table as well as infiltration of surface water into
sediments, forming a surficial mixing zone with
groundwater discharging from the adjacent
aquifer (Robinson et al. 1998; Ataie-Ashtiani
et al. 1999; Zhou et al. 2006). The groundwater
behavior in an unconfined aquifer with a mild
sloping face in response to a tide is affected by
two factors that do not exist in a confined aquifer.
These factors are the infiltration of saltwater from
the top of the beach slope into the aquifer at high
tide and tidal pumping with a free water table.
The latter effect is intensive by a mild sloping
beach and the existence of a seepage-face at the
sea boundary of the groundwater.
The tidal level and groundwater water level
fluctuation measurements are studied in Vembar
river estuaries, Karamaniyar river estuaries and
dug wells near to coastal mining (Fig. 14.9).
14.1.5.1 Vembar River Estuary
The experimental setup was deployed in two
selected sites along the Vembar estuary (from 8
am to 5 pm in a day). The minute wise fluctuation was recorded using an automatic data logger
device. This device has the capability to monitor
the pressure difference and the temperature
change. The results reveal that high tide exhibits
around 8 am and 5 pm and low tide is noticed
around 2 pm in the estuarine mouth monitoring
well. This fluctuation is barely because of the
medium of water transport. The sediment texture
of this site is 99% sand, which allows seawater to
easily pass through. However, in other sites (site
no. 2, 3, 4) the fluctuations vary with respect to
high tide and the level becomes almost stable.
This may be due to the presence of clay as it is a
poor medium for water transmittance. The hourly
tidal fluctuations are shown in Fig. 14.10. The
distribution of temperature in the study area is
dependent on the temperature of the incoming
river and seawater, the mixing processes and on
the exchange of heat through the surface. The
effect of temperature is to increase the density
difference between river and seawater. The study
area experiences the tidal-induced water table
motion in the phreatic aquifer of the shoreline.
The water table range varies between 4.25 and
3.38 mbgl during 2011–2013. In the monitoring
well the water table is observed as 2.78 mbgl.
This reveals that the tide-induced change in water
level is around 0.68 m (Simon Peter et al. 2014).
14.1.5.2 Karamaniyar River Estuary
In the Karamaniyar river estuary, it is seen that
the distribution is controlled mostly by the local
weather conditions. Surface temperature of the
water chiefly depends on the incoming solar
radiation; the estuary being a shallow one, the
distribution appeared to be dominated by the
diurnal effect rather than tidal effect. The study
area experiences the tidal-induced water table
motion in the phreatic aquifer of the coastal
196
S. Selvakumar and N. Chandrasekar