Geoscience Reference
In-Depth Information
MASS TRANSPORT MODELING IN THE UPPER
KODAGANAR RIVER BASIN, TAMILNADU, INDIA
N. C. MONDAL
∗
andV.S.SINGH
National Geophysical Research Institute, Hyderabad-500 007, India
∗
ncmngri@yahoo.co.in
Groundwater in Upper Kodaganar River basin, Tamilnadu, southern India, is
polluted due to discharge of untreated e
uents from 80 functional tanneries.
Total dissolved solids (TDS) are observed ranging from 2000 to 30,575 mg/l in
open dug wells in the tannery cluster. A mass transport model was constructed
to study the pollutant migration. The basin covering an area of 240 km
2
was
chosen to construct the groundwater flow model in the weathered part of
unconfined aquifer condition. The shallow groundwater potential field com-
puted through flow model was then used as input to mass transport model.
MT3D computer code was used to simulate the mass transport model. The
mass transport model was calibrated with field observation. Sensitivity analy-
sis was carried out whereby model parameters viz. transmissivity, dispersivity
etc. were altered slightly and the effect on calibration statistics is observed.
This study clearly indicates that the transmissivity plays a sensitive role than
the dispersivity indicating that the migration phenomena are mainly through
advection rather than dispersion. The study also indicated that even if the
pollutant sources were reduced to fifty percent of the present level, the TDS
concentration level in the groundwater, even after two decades, would not be
reduced below half fold of TDS of present level.
1. Introduction
The study area, a granitic rock formation in Tamilnadu, southern India,
possesses poor groundwater potential and serious contamination of both
surface water and groundwater has been reported in this area as a result of
uncontrolled discharge of untreated euents by 80 tanning industries for the
last three decades.
1
-
4
The health of the rural farming community and peo-
ple working in the tanning industries have been seriously affected and they
are suffering from occupational diseases such as asthma, chromium ulcers
and skin diseases.
5
About 100-km
2
area of fertile land has lost its fertil-
ity. TDS concentration in groundwater at some pockets varies from 17,024
to 30,575 mg/l.
6
As the discharge of euents is continuing, a prognosis
of further pollutant migration is carried out using a mathematical model.
A numerical model of the area was developed using the finite difference
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