This chapter deals with one aspect of ratification, that is, soil moisture, in lower cauvery delta.

A sharp decline in the volume of water available to the cauvery irrigation system In Tamil Nadu., combined with potential changes in water availability on account of climate change, raise serious concerns about crop yields and crop production in the lower cauvery delta. This chapter explores the changes in soil moisture by estimating a moisture index based on rainfall and evapotranspiration for the three delta districts of thanjavur, nagapattinam and tiruvarur, using a consistent dataset for a period of 58 years, 1957-2015.

The main finding of the analysis is that there is a statistically significant declining trend in the moisture index in all the three districts. By this measure, there has been a rise in threse districts over a relatively long period.

Authors argue that climate change, specifically a rise in annual mean temperatures, may be an important factor in changes in the moisture index (by affecting evapotranspiration), and recommend further examination of the factors affecting the moisture index.