In any natural area or water body, evapotranspiration is one of the main outcomes in the water balance equation. It is also a crucial component of the hydrologic cycle and considers as the main requirement in the planning and designing of any irrigation project. The climatic parameters for the Ishaqi area are calculated from the available date of Samarra and Al-Khlais meteorological stations according to a method for the period (1982–2017) according to Fetter method. The results of the mean of rainfall, relative humidity temperature, evaporation, sunshine, and wind speed of the Ishaqi area are 171.96 mm, 49.67%, 24.86 C°, 1733.61 mm, 8.34 h/day, and 2.3 m/sec, respectively. Values of Potential Evapotranspiration are determined by utilizing equation Thornthwiat, Lerner's methods. is applied for computation water balance. The water surplus amount of the study area is 89.9 mm, while the water deficit amount of the study area is 884.228 mm. The type of climate was determined by applying three climate classifications. The area was considered as arid climate according to the Mather and Brown & Cocheme classification.
