Irrigation Scheduling of Rabi Crops in Salandi Sub-Catchment Using Cropwat

In this paper, an attempt has been made for a systematic and scientific planning of water resources availability in Salandi sub-catchment, Odisha for its optimal utilization, as it is limited in space and time. Use of modern techniques in the command economizes consumption and saving of water brings greater areas under irrigation and ultimately results in more agricultural yield. The study estimated the reference crop and actual evapotranspiration (Et_o and ET _c) respectively and the irrigation water requirement of paddy, vegetable and pulse crops in the sub-catchment using CROPWAT 8.0 model. CROPWAT 8.0 FAO Penman Monteith method is used to calculate the Reference Crop Evapotranspiration (ET_o) and United States Department of Agriculture (USDA) S. C. method has been employed to calculate the effective rainfall. The recorded climatic data, crop and soil data from 2010 to 2016 are computed with the model based on the Food and Agriculture Organization (FAO) paper number 56 (FAO 56). Amount of water supplied at different growth stages, soil water depletion and Crop Water Requirement (CWR) and irrigation scheduling for crops are modelled. The results of the study show that that for the Salandi sub-catchment, ET_o varies from 2.87 mm/day to 7.83 mm/day and the effective rainfall varies from 9.8 mm to 166.5 mm. Crop Water Requirements are 636.9 mm/dec for paddy, 285.1 mm/dec for vegetables, and 321.7 mm/dec for pulses respectively. Total gross irrigation and total net irrigation are 646.9 mm and 452.8 mm for paddy, 383.3 mm and 268.3 mm for vegetables and 360.7 mm and 252.8 mm for pulses respectively. Salandi reservoir can be scheduled for water use efficiency based on these findings for rabi season.