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Project Title: 
Preventing Salt Water Encroachment in Layered Aquifers of Ramanathapuram Coast, Tamilnadu, India.

Thematic Area:
Coastal Hydrology

Location:
Ramanathapuram coast occupies southeastern part of Indian sub-continent. 
Longitude 780 15 & 790 25 
Latitude 90 10 & 100 00
The project area has an aerial extent of 2195 Km2 (Figure1).

Objective:
To evaluate the ground water resources of various layered aquifers sequence of Ramanathapuram coast through an integrated approach.
To identify the appropriate hydro-geomorphic units helpful in recharging ground water.
To develop a computer model for analyzing the layered coastal aquifer and for evaluating impacts on development, and
To propose possible recharge strategies to protect the fresh water within coastal environments

Abstract:
The project area is comprised of recent to sub-recent alluvium, which is underlined, by sandstone, shale and clay of tertiary and cretaceous age. The above formations constitute multi aquifer system namely; (i) Shallow [Water Table aquifer] (ii) intermediate [Semi Confined aquifer] and (iii) Deeper aquifer [Confined aquifer]. Crystalline basements are encountered at 3860 m south east of Ramanathapuram and Mandapam at a depth of 1640 m. Crystalline basement is of mostly of gneiss. 
The long-term correlation between rainfall and water level data indicates a remarkable rise in the water level after monsoon rain. 
Aquifer Parameters have been evaluated through pumping test.
The hydro geochemistry of multi aquifer system have been evaluated and presented in figures (Figure2, Figure3, and Figure4).
The existence of multi layer aquifer system has been established through geophysical investigation.
A groundwater modeling have been attempted to establish saline intrusion.

Data Used:
Geology, Hydrometeorology, Aquifer Parameters, Geochemistry and Geophysics.

Highlights/Findings: 
Horst and Graben structure identified from the fence diagram prepared with the bore well data of CGWB and ONGC.
From the rainfall and water level studies, it is inferred that only a moderate recharge occur during post monsoon period. 
The high transmissivity zones have been identified which is due to the presence of palaeochannels. 
From the water qualities of shallow and intermediate aquifers, the mixing between these zones can be established. Salinity is identified near the coast in both the above aquifers. 
Deeper aquifer found to be a better potential zone both qualitatively and quantitatively.
Modeling confirms a saline intrusion near the coast. 
Inland high salinity also occurs may be due to salt-water upcoming, which is to be confirmed through isotope hydrological studies.

Date of Project Completion:
30.11.2002

Total Coast of Project:
Rs. 9,45,300.00

Project Investigator:
Dr. J. Francis Lawrence
Reader in Geology,
Presidency College,
CHENNAI 600 005.
Phone: (Off.) 044 28544894 (Ext. 34)
(Res.) 044 24460788 
Fax: 044 - 28510732
Email: joflaw[at]hotmail[dot]com