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Plant Science Today (PST)

Research Articles

Vol. 13 No. sp5 (2026): Recent Advances in Agriculture

Saltwater intrusion and soil salinisation in the coastal area of Chengalpattu district in Tamil Nadu

DOI
https://doi.org/10.14719/pst.14720
Submitted
30 March 2026
Published
22-07-2026

Abstract

Chengalpattu has been an agriculturally based coastal district in Tamil Nadu with a major land area under paddy cultivation. Here, the major environmental challenges are soil salinisation and saltwater intrusion, which affect the area's agricultural productivity. This study reports an integrated analysis of climate-driven soil salinisation in the Chengalpattu district of Tamil Nadu, using a multi-dataset analytical approach covering the period of 2013–24. Seven institutional secondary datasets comprising approximately 8300 records have been synthesised to examine the interactions across the rainfall, groundwater, surface water, soil and crop production systems. Rainfall variability has been analysed using long-term mean statistics and the Mann-Kendall trend tests, groundwater hydrochemistry, water table dynamics and soil salinity pattern have been evaluated using descriptive and non-parametric statistical methods. Results indicate extremely high inter-annual rainfall variability with a CV  49.5 %, including five deficit rainfall years during the study period. Groundwater quality of 643 station-year records from 2015–23 has indicated a mean electrical conductivity (EC) value of 1032 µS/cm (marginal) with chloride ranging from 121–216 mg/L. Mann-Kendall analysis has revealed a significant declining water table trend where the τ = -0.818, Z = -3.43 and p < 0.001 with depth reducing from 6.90 m below ground level (mbgl) in 2013 to 3.35 mbgl in 2021, a net rise of 3.55 m. Surface water EC has increased from 212 µS/cm in 2015 to 1013 µS/cm in 2022, where the τ =0.6411, p = 0.029, while shallow dug-well EC averaged 1521 µS/cm, of 47 % higher than bore wells, indicating greater vulnerability of shallow aquifers. Soil analysis of 4617 samples has shown 59.9 % non-saline, 32.6 % slightly saline, 6.2 % moderately saline and 1.3 % highly saline soils. Rice cultivating areas have declined by 52.3 % from 97738 ha in the year 2015–16 to 49917 ha in the year 2022–23, with yield ranging from  3.55 – 4.97 t/ha. These findings highlight increasing salinisation risk and emphasise the need for proactive groundwater management, soil health restoration and adaptation of salt-tolerant crops in the coastal agricultural system.

 

 

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