This study aims to determine the gross irrigation water requirement GIWR for durum wheat crop (Sham3) using climate , crop, and soil in Mosul area .
The experiment was carried out in the field of the technical institute of Mosul for the cultivation durum wheat crop cv.Sham3 in season 2009/2010.
The consumptive water use was determined by multiplied the calculated reference crop evapotranspiration using Penman-Monteith equation based on climatological data for Mosul station which considered the nearest to the experiment , by a crop coefficient depended on the growth of stages ( initial , development , mid , and end stage) .
The GIWR was 175 mm.season-1 and determined based on the effective rainfall, consumptive water use , change in soil water storage in root zone , and efficiency of irrigation . Four irrigation treatments were used 100% , 50% , 25% from GIWR , and without irrigation , only rainfall .The results showed that the crop properties such as the grain yield increases with irrigated in full GIWR and reached to 5.5 t/ha ,While it decreases by 20% with irrigated in 50% from GIWR .

Keywords: Irrigation water requirement, Penman-Monteith, Durum wheat, Mosul.