Precipitation is one of the transportation components in hydrological cycle. The magnitude of precipitation swings with time and space. Majorly India receives precipitation in the form of rainfall. Precipitation plays a key role in the rainfed agriculture. The present study deals with the rainfall characteristics of Tiruchirappalli district, Tamil Nadu. Seasonal rainfall data from eighteen rain gauge stations (1971-2012) have been taken for analysis of seasonal and annual rainfall pattern of Tiruchirappalli district. Mean rainfall of the district is about 696 mm. The highest rainfall of 1247 mm recorded in the year 2005 and the lowest precipitation of 227 mm recorded in the year 1976. About 48 percent and 35 percent of the rainfall received in North East and South West Monsoon, respectively. Spatial rainfall distribution was studied with the help of Kriging interpolation technique and respective maps were prepared with Geographical Information System. The percentage departure of annual rainfall is classified under the category of excess, normal and large excess category. South East and central part of Tiruchirappalli receives moderate to low rainfall. North East parts of Tiruchirappalli district such as pullambadi, Lalgudi and nearby areas received maximum rainfall during North East Monsoon and South West Monsoon. In winter season Manapparai and Vaiyampatti region received more rainfall while in summer season Thottiam and Mayanur area received more rainfall. The two major highlighted crops in Trichy district are Banana and Onion. Tiruchirappalli district is one of the Banana growing belts in Tamil Nadu. Spatial distribution of rainfall maps will be helpful to form a crop plan for different crops to increase the agricultural productivity of Tiruchirappalli district and to ensure the food security.

Groundwater is the primary source for drinking, irrigation, and industrial purposes. Groundwater provides about 24 per cent of global water supply. Groundwater level fluctuates depending on the groundwater recharge and discharge from the aquifer. The climate change, changing rainfall pattern and growing water demand lead to the groundwater level variation year by year. Rainfall is the major source for groundwater recharge. As rainfall increases, groundwater level also increases. Theni District also called Cardamom city located in the foot of Western Ghats is chosen as the study area. The major source of irrigation was well. For analysis of groundwater level status, the Average-Ground Water Level data and Categorization of the firkas in Theni district was collected from State Ground and Surface Water Resources Data Center. Arithmetic averages of Rainfall of stations under the Theni district was collected from India Meteorological Department. Groundwater level rise and fall analysis of Average-Groundwater level data (2011 to 2019) was carried out using the line chart. Comparative analysis was done using Rainfall data Vs Average-Groundwater level data (2014-2018). Considering the last five years, the groundwater level in Theni District has increased. The statistical correlation between the rainfall and groundwater level fluctuation was poor. Categorization of firkas was used as a performance indicator. It was observed that the Safe Firkas increased from 18% to 41% and the Critical Firkas increased from 6% to 12%. In Periyakulam and Theni Taluk there is no change in Firkas category and remains the same as on 2011. This helps in focusing groundwater development in those taluks which are in the fringe of groundwater status.