Determining of reference evapotranspiration by different equations for Duhok province

Water management for agricultural production is the most important source in Kurdistan region. Crop water requirement and determining of evapotranspiration (ET) namely (the water consumption from the plant transpiration, and evaporation of soil surface), which has a direct impact on the agriculture yield. First of all, this research was conducted to determine reference evapotranspiration in Duhok, Zakho, Akre, Amedi, Sumeel, Bardarash, Bamerne, Kanimase and Mangesh city in Duhok region. For this purpose, long-term and 2018 climate data were obtained from the climate stations of these provinces. Estimation methods have been preferred because of difficulties in directly determining ET values. For this purpose, Hargreaves, Blaney-Criddle (FAO), Turc, Priestly-Taylor, Makkink, FAO-56 Penman-Monteith and Kimberly-Penman methods were used. In general, Blaney-Criddle method gave the highest values, while Priestly-Taylor and Makking methods gave lower values. Kimberly PM, Hargreaves, Turc and Priestly-Taylor methods were in the same group with FAO56 PM method. Average of ET values obtained by these 5 methods were taken as input parameter and, the mean temperature, maximum temperature, minimum temperature, relative humidity, wind speed and sunshine duration were taken as input parameters for Multiple regression analyses. As a result; The model obtained by average temperature, humidity and sunshine times (R2: 0,932) was determined as the best model. The model, which was tested with annual data, was presented by both farmers and researchers as an easy and highly accurate model. Keywords : Reference Evapotranspiration, Plant water consumption, Duhok, Ref-ET, Climate.