Groundwater quality of Chennai, Tamil Nadu (India) has been assessed during different seasons of year 2012. Three physical (pH, EC, and TDS)

A review has been made to understand the hydrogeochemical behaviour of groundwater through statistical analysis of long term water quality data (year 2005-2013). Water Quality Index (WQI), descriptive statistics, Hurst exponent, fractal dimension and predictability index were estimated for each water parameter. WQI results showed that majority of samples fall in moderate category during 2005-2013, but monitoring site four falls under severe category (water unfit for domestic use). Brownian time series behaviour (a true random walk nature) exists between calcium (Ca 2+) and electric conductivity (EC); magnesium (Mg 2+) with EC; sodium (Na +) with EC; sulphate (SO 2− 4) with EC; total dissolved solids (TDS) with chloride (Cl −) during pre-(2005-2013) and post-(2006-2013) monsoon season. These parameters have a closer value of Hurst exponent (H) with Brownian time series behaviour condition (H = 0.5). The result of times series analysis of water quality data shows a persistent behaviour (a positive autocorrelation) that has played a role between Cl − and Mg 2+ , Cl − and Ca 2+ , TDS and Na + , TDS and SO 2− 4 , TDS and Ca 2+ in pre-and post-monsoon time series because of the higher value of H (>1). Whereas an anti-persistent behaviour (or negative autocorrelation) was found between Cl − and EC, TDS and EC during pre-and post-monsoon due to low value of H. The work outline shows that the groundwater of few areas needs treatment before direct consumption, and it also needs to be protected from contamination.

The good quality of groundwater is important for the purpose of future planning and management. The present study has been undertaken to provide an overview on the status of groundwater quality through physicochemical parameters namely pH, alkalinity, total hardness, total dissolved solids, chloride, fluoride, nitrate, phosphate and iron through laboratory analysis. Samples have been collected from seven wells located in Chennai costal region of state Tamilnadu, India. The laboratory-based results shows that the mean value of pH is 7.29, alkalinity (308.57 mg/l), total hardness (285.71 mg/l), chloride (175.71 mg/l), iron (0.71 mg/l), nitrate (13.57 mg/l), phosphorus (2.71 mg/l) and total dissolved solids (924 mg/l), respectively. The geo-database water quality parameters were created in Geographical an Information System. Further, the kriging a geo-statistical method of interpolation is applied to know the health of groundwater in the then-sampled area. This interpolation method has been used to predict spatial distribution physicochemical parameters in the form of contour. Local planners and policy makers may utilize these results for efficient management of groundwater resources in this area.