Time Series Analysis of Groundwater-Quality Parameters of Tiruchirappalli District, Tamil Nadu

Abstract

Abstract Groundwater, an essential natural resource that plays a crucial role in sustaining life and supporting various socio-economic activities. The study area, Tiruchirappalli district located in Tamil Nadu, India, has experienced an increased demand for groundwater due to rapid growth in population, industrial development and urbanization. The present study focuses on identification of trends in the concentration of nine groundwater-quality parameters in the unconfined aquifers, across 11 blocks located in this district from 1980 to 2013. To achieve this, the analysis utilized three statistical trend tests namely Linear Regression Test (LR), Mann-Kendall test (MK) along with Sen’s slope estimator test and Innovative Trend Test (IT). The results revealed significant increasing trends in the concentrations of SO42-, Mg2+, Na+ EC, TH, Cl-, F- and NO3--N whereas significant decreasing trends were found in the concentration of Ca2+ in almost all parts of the district. Among the three tests, MK Test and LR Test has shown the similar trend at significance level (α = 5%) for all the parameters across the study area. However, the IT Test showed increasing or decreasing time series for the same groundwater-quality parameters, even in cases where the LR and MK tests did not show statistically significant trends. This indicates that the IT test is comparatively more sensitive to variations in the data as compared to LR and MK trend tests.