Estimating Crop Water Requirements and Assessing Irrigation Water Distribution Cost for Rice Production Using a Pipe Network

In this paper we attempted to estimate crop water requirement for rice production in an Indian state. We also assessed the cost of irrigation water distribution. The study area (phases I and II) belongs to a humid subtropical region with sandy clay loam soil. Here, farmers are presently using a partial border strip irrigation technique with supply pipe and riser. First, the Man Kendall test is performed on six years monthly rainfall data to check for the presence of a trend. We found that the data is random at a 5% significant level. Thereafter, the crop water requirement for rice production is calculated based on FAO guidelines and average monthly rainfall. The crop water requirement in the study area amounted to 7.22 lakh m(3), of which Phase I is 6.12 lakh m(3) and Phase II is 1.2 lakh m(3). In order to fulfil this requirement, irrigation was conducted through a pipe network. Actual irrigation value is calculated based on four years of irrigation water distribution data. Finally, the average depth of water logging, time of pumping, and cost for surplus irrigated water are calculated. We found that at a rate of INR 5 per unit kWh, the cost of annual surplus irrigated water for rice is 4.32 lakhs for an irrigation area of 1.284 km(2) (phase I), and the same is INR 0.84 lakh for 0.252 km(2) (phase II). This loss can be minimized using proper scheduled regulation of irrigated water using the pipe distribution network.