Trends and effects of rainfall on groundwater recharge in Namakkal district of Tamil Nadu: Analysis using the Mann-Kendall test and transfer function model

Persistent rainfall determines the potential groundwater availability; hence, their association is assessed in this paper. The Mann-Kendall test is used on time series data, and a linear transfer function model is fitted. The Mann-Kendall test shows a negative trend in the groundwater level during the northeast monsoon and an increasing trend in all seasons. The rising trend of rainfall raised groundwater availability throughout the year except during the north-east monsoon. The linear model specifies that rainfall affected the monthly average groundwater level which led to the recharge of the dynamic groundwater level.