Effect of climatic parameters and cultivation pattern on Evapotranspiratin and Irrigation Hydromodul in some areas of northwest Iran

In our country, more than 90% of water, is used in agriculture. The aim of this research, is to extract the changes of cultivation pattern water use, in some regions of the northwest of the country, as a function of climatic parameters. In first step, the meteorological data of Urmia, Makoo, Maragheh, Mianeh and Khalkhal stations were collected. In second step, using Cropwat 8 software, the grass evapotranspiration, as the reference plant, was extracted at each station. The cultivation pattern of the desired areas was also extracted from the sources. In the last step, using the Weibull transformation coefficient, the hydromodule with different return periods was extracted for each region. The results showed that the average of grass potential evapotranspiration as reference plant, for Urmia, Makoo, Maragheh, Mianeh and Khalkhal stations was 3.14, 2.87, 3.92, 3.8 and 2.89 mm/day respectively. The average irrigation hydromodulus of five mentioned areas, was abtained 0.38, 0.33, 0.53, 0.56 and 0.49 l/s.ha respectively. By taking the linear changes function, by changing the return period from 2 to 200 years and reducing the occurrence probability, the amount of irrigation hydromodule in Urmia, Makoo, Maragheh, Mianeh and Khalkhal stations was increased 0.085, 0.083, 0.166, 0.046 and 0.8 l/s.ha, respectively, and by taking the exponential changes function, also, was increased 0.098, 0.1, 0.2, 0.049 and 0.094 l/s.ha respectively.