MODELLING NET IRRIGATION WATER REQUIREMENTS AND IRRIGATION SCHEDULING OF BORO RICE USING FAO-CROPWAT 8.0 AND CLIMWAT 2.0: A CASE STUDY OF RAJSHAHI REGIONS, BANGLADESH

The FAO-Penman-Montieth equation is commonly indicated as the standard way for calculating reference and crop evapotranspiration notwithstanding crop and irrigation water requirements using the FAO CROPWAT 8.0 and CLIMWAT 2.0 models, according to the findings of this study. The correct measurement of irrigation water demand trends has a substantial impact on water resource planning for agricultural development and expansion in Bangladesh's northern areas. At the 5% level of significance, the net irrigation water requirement of boro rice shifted into an increasing pattern confined between 74.0 mm and 7.4 mm each year. In preference to temperature, the tendency shifted to an integrative impact of wind speed, relative humidity, rainfall, and Evapotranspiration (ET0). For boro rice, the monthly reference evapotranspiration (ETo) was calculated to be 3.69 mm/day. Within the month of April, the greatest crop water requirement (ETc) was 61.0 mm/dc, and the overall crop water requirement (ETc) was 586.0 mm/dc, including land preparation. In the month of March, the maximum irrigation demand was 52.0 mm/dec, with a total irrigation demand of 621.8 mm/dc for the entire crop season. Boro rice was irrigated, and the CROPWAT model estimated a net irrigation water requirement of 448.2 mm and a gross irrigation water requirement of 595.1 mm (with 70% field efficiency) for a successful harvest. These findings could be utilized to improve water efficiency and streamline boro rice production in northern region of Bangladesh's Rajshahi region.