Forecasting the groundwater levels using the stochastic time series models in hard rock region of Pollachi, Tamil Nadu

The present study aims to investigate the potential impacts of rainfall variation on groundwater levels by analyzing the relationship between long term rainfall data (1936 to 2010) and groundwater levels (1971–2010) for ten observation wells in over exploited blocks (>100) of Pollachi Taluk, Coimbatore, Tamil Nadu. Correlation analysis between rainfall and groundwater level shows that annual rainfall display a moderate correlation with annual groundwater levels and any change in rainfall influences the water level. Groundwater level respond to rainfall variations with a time lag which was evaluated equal to one year using cross correlation. Forecasting of groundwater levels is very useful for planning integrated management of groundwater and surface water resources in a basin or region. In this study, linear stochastic time series models known as Autoregressive Integrated Moving Average (ARIMA) models were used to forecast groundwater levels for Pollachi based on the procedure of model development. The predicted results of the developed models are in close agreement with the observed data. Hence the developed models can be used to forecast groundwater levels with reasonably accuracy in the region under study.