Performance Assessment of an Irrigation System in Tamil Nadu, India

Tamil Nadu in India has 7% of country’s population but 3% of surface water resource. About 40% of population lives below poverty line live in rural areas depending directly on agricultural activities during the year 2004–05. The state receives most of the rainfall during October to December. Hence, it is vital to conserve water when available. Most of the irrigation and power projects in Tamil Nadu came up before 1980 as a consequence of 5 years plans of Government of India. These projects were designed in such a way to suit the conditions prevailed during the years of implementation. As it is a fact that the water requirements and water availability change from time to time, the assessment of the present irrigation systems becomes necessary through which we get new strategies to implement, thereby satisfying the future demands. Hence, a study on the performance of the Palar–Porunthalar irrigation system in Tamil Nadu was taken up. The performances of the system since inception were studied. The crop water requirement for this irrigation system has been arrived based on duty area approach and followed till date from the year of inception. In this study, crop water requirement for the entire system was assessed using CROPWAT software. It is observed that twenty percent of water is saved by adopting this model. Also, for many years the water obtained during monsoons was either not sufficient or discharged as flood due to heavy intensity. The possibility of increasing the storage capacity of the dam was assessed using geographical information system (GIS) as it can make the system function more appropriate at times of flood. From this study, we come to know that the CROPWAT model has been more optimistic than the conventional method and the increase in dam height by 1.65 m is possible which in turn increases the storage capacity by 20 percent. It is observed that GIS serves as an effective tool for the management of irrigation system. The details of the data collected, analyses, methodology and strategies to be adopted are presented in this paper. © 2019, The Institution of Engineers (India).