Abstract: Dynamic nature of ground water system in coastal area is evidenced in many studies. In agriculture this dynamism also cause absolute scarcity where expected irrigation water requirement could not be met from available ground water. Major indicators of groundwater scarcity are irrigation investment and irrigation costs which are economically analysed in this study in the two selected non-saline coastal blocks viz-Vanurand Marakkanam of Villupuram district in Tamil Nadu, the semi critical (SC) and over- exploited (OE) blocks of ground water use respectively. The OE block exhibited high investment in irrigation compared to SC block due to additional investments in bore well installation. The irrigation cost share in input costs was more in OE block than SC block and hence low economic returns in ‘OE’ block. The regression analysis of Resource Use Efficiency of irrigation ground water estimation also proved that the irrigation input had negative influence on gross income in OE block.

Keywords: semi critical (SC), over- exploited (OE), ground water system, coastal area.