A Study on Evolving Optimal Cropping Patterns in Groundwater Over-exploited Region of Perambalur District of Tamil Nadu

Falling groundwater tables and depletion of economically accessible groundwater resources would have major social and economic consequences. The present study has been taken up with the overall objective of evolving optimal crop plans to sustain the use of groundwater resources for irrigation. Perambalur district was purposively selected for the study as it mainly depends on groundwater for its irrigation. Linear programming technique was used to evolve optimal crop plans. The constraints identified were primarily irrigation water, besides land availability during the cultivating seasons and capital. Six typical farms were selected, one each for the open well, wells in tank command area and tubewell-irrigated farms in critical and over-exploited groundwater regime and also for semi-critical and safe groundwater regime. The results of the optimal crop plans derived showed that the irrigation water-use in the critical period could be reduced by 24.30, 4.54 and 51.71 hours of pumping in ordinary wells, wells in tank command area and tubewell-irrigated farms, respectively in critical and over-exploited groundwater regime sample farms. In the semi-critical and safe groundwater regime sample farms, the optimal crop plans revealed that the irrigation water-use in the critical period could be reduced by 4.61, 3.99, and 4.73 hours of pumping in ordinary wells, wells in tank command area and tubewell-irrigated farms, respectively. Area under high water intensive crops namely, paddy and sugarcane declined almost in all the optimal crop plans. Area under low water intensive crops (groundnut, gingelly and tapioca) showed an increasing trend in all optimal crop plans. The net income of the sample farms increased marginally or considerably in the optimal crop plans of both the critical and overexploited groundwater regime sample farms and semi-critical and the safe groundwater regime sample farms