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Why seawater intrusion has not yet occurred in the Kaluvelli-Pondicherry basin, Tamil Nadu, India
- Source :
- Hydrogeology Journal, Hydrogeology Journal, 2017, 25, pp.1893-1907. ⟨10.1007/s10040-017-1558-4⟩
- Publication Year :
- 2017
- Publisher :
- HAL CCSD, 2017.
-
Abstract
- Worldwide, coastal aquifers are threatened by seawater intrusion. The threat is greatest when aquifers are overexploited or when recharge is low due to a semi-arid or arid climate. The Kaluvelli-Pondicherry sedimentary basin in Tamil Nadu (India) presents both these characteristics. Groundwater levels in the Vanur aquifer can reach 50 m below sea level at less than 20 km inland. This groundwater depletion is due to an exponential increase in extraction for irrigation over 35 years. No seawater intrusion has yet been detected, but a sulphate-rich mineralization is observed, the result of upward vertical leakage from the underlying Ramanathapuram aquifer. To characterize the mechanisms involved, and to facilitate effective water management, hydrogeological numerical modelling of this multi-layered system has been conducted. Existing and acquired geological and hydrodynamic data have been applied to a quasi-3D hydrogeological model, NEWSAM. Recharge had been previously quantified through the inter-comparison of hydrological models, based on climatological and surface-flow field measurements. Sensitivity tests on parameters and boundary conditions associated with the sea were performed. The resulting water balances for each aquifer led to hypotheses of (1) an offshore fresh groundwater stock, and (2) a reversal and increase of the upward leakage from the Ramanathapuram aquifer, thus corroborating the hypothesis proposed to explain geochemical results of the previous study, and denying a seawater intrusion. Palaeo-climate review supports the existence of favourable hydro-climatological conditions to replenish an offshore groundwater stock of the Vanur aquifer in the past. The extent of this fresh groundwater stock was calculated using the Kooi and Groen method. http://link.springer.com/article/10.1007/s10040-017-1558-4
- Subjects :
- Hydrology
geography
geography.geographical_feature_category
Hydrogeology
Coastal aquifer
010504 meteorology & atmospheric sciences
Artesian aquifer
India
Aquifer
Groundwater recharge
010501 environmental sciences
Sedimentary basin
Structural basin
01 natural sciences
[SDU]Sciences of the Universe [physics]
Numerical modeling
Semi-arid climate
Earth and Planetary Sciences (miscellaneous)
Groundwater discharge
Sedimentary rocks
Groundwater
Geology
0105 earth and related environmental sciences
Water Science and Technology
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- Hydrogeology Journal, Hydrogeology Journal, 2017, 25, pp.1893-1907. ⟨10.1007/s10040-017-1558-4⟩
- Accession number :
- edsair.doi.dedup.....b3cf6be73fa52eae8332726c3d4162d0