A total of 20 groundwater samples were collected from both dug and bore wells of southern Tiruchirappalli district and analyzed for various hydrogeochemical parameters. The analyzed physicochemical parameters such as pH, electrical conductivity, total dissolved solids, calcium, magnesium, sodium, potassium, bicarbonate, carbonate, sulfate, chloride, nitrate, and fluoride are used to characterize the groundwater quality and its suitability for drinking and irrigational uses. The results of the chemical analysis indicates that the groundwater in the study area is slightly alkaline and mainly contains Na⁺, Ca²⁺, and Mg²⁺ cations as well as HCO₃ ²⁻, Cl⁻, SO₄ ²⁻and NO₃ ⁻ anions. The total dissolved solids mainly depend on the concentration of major ions such as Ca, Mg, Na, K, HCO₃, Cl, and SO₄. Based on TDS, 55 % of the samples are suitable for drinking and rest of the samples are unsuitable for drinking. The total hardness indicates that majority of the groundwater samples are found within the permissible limit of WHO. The dominant hydrochemical facies for groundwater are Ca–Mg–Cl, Ca–HCO₃, and Ca–Cl type. The USSL graphical geochemical representation of groundwater quality suggests that majority of the water samples belongs to high medium salinity with low alkali hazards. The Gibb’s plot indicates that the groundwater chemistry of the study area is mainly controlled by evaporation and rock–water interaction. Spearman’s correlation and factor analysis were used to distinguish the statistical relation between different ions and contamination source in the study area.

The coastal landuse and land cover features in the South West coast of Kanyakumari are dynamically regulated due to marine and terrestrial processes and often controlling by natural and anthropogenic activities. The primary objective of this study is to estimate the decadal changes and their transformations of landuse and land cover (LULC) features under Level II category of USGS-LULC Classification System using Landsat ETM+ and TM images using Maximum Likelihood Classifier (MLC) algorithm for the period 2000–2011. The classified LULC features are categorized as beachface land cover, cultivable lands, plantation and shrub vegetation, fallow land, barren land, settlements and built-ups, water bodies, and mining area, etc. The geo-database is prepared for LULC feature class with an attributes of name, location, area and spatial distribution, etc. It shows the larger area in beachface land cover (sandy beaches, foredunes, uplands, Teri dunes (laterite) and associated nearshore landforms), plantations, cultivable lands, fallows, and barren lands are converted into built-ups and it increases more than twice in the period of 10 years. Using GIS techniques, the analysis of change detection matrix reveals that the total area of 45.90 km2 in different LULC features periodically shifted or transformed from one state to another one or more states, i.e. the beachface land cover area of 1.24 km2 is encroached for built-ups and 0.63 km2 for placer mining during the decade. Meanwhile, the area of 0.21 km2 in this cover is transformed into wetlands and saltwater bodies. During the past decade, the expansion of area in the built-ups and settlements are directly proportional to the growth of population, which produces severe threat to the coastal resources. Accuracy assessment of classified images shows the overall accuracy is estimated as 81.16% and 77.52% and overall Kappa coeffient statistical values of 0.83 and 0.76 for the year 2000 and 2011 respectively. Ground truth verification of the extracted LULC features performed using 120 samples (10 samples per class) reveals that the accuracy of classified features is 89%. This indicates the acceptable accuracy of the classified LULC features for landuse and land cover change studies. The geodatabase of LULC features is used as primary source for sustainable land resource management in the coastal region