Estimation of Irrigation Water Requirements for Existing and High-value Crops in the Appapuram Channel Command Area Using the FAO AquaCrop Model

Abstract

The present study aims to estimate irrigation water requirements and crop yields for existing and high-value crops cultivated in the Appapuram Channel Command of the Krishna Western Delta (KWD). The command area, covering approximately 10,000 ha, is predominantly cultivated with rice, cotton, maize, chilli, black gram, green gram, and sugarcane during the Kharif and Rabi seasons. In the KWD irrigation system, canal water is supplied continuously until about ten days prior to harvest, meeting the water needs for land preparation, field saturation, crop establishment, and subsequent growth stages. Crop water requirements were estimated by considering saturation requirement, effective rainfall, evapotranspiration, and seepage–percolation losses. The FAO AquaCrop model was employed to estimate irrigation water requirements and crop yields using long-term meteorological data (2000–2015), while effective rainfall was computed using the CROPWAT model based on the USDA–SCS method. The results showed total irrigation water requirements of 1010 mm for paddy, 656.0 mm for maize, 573.3 mm for black gram, 816.2 mm for chilli, 672.2 mm for cotton, and 552.2 mm for green gram across both seasons. The study identified misutilization of canal water and underutilization of groundwater resources, leading to a cultivated area lower than the actual irrigation potential. The findings highlight the effectiveness of the AquaCrop model as a decision-support tool for irrigation planning and efficient water management in canal command areas.