Estimation and mapping evapotranspiration using climatic parameters in GIS: A Case Study in Khorasan Province

One of the ways to reduce the water crisis in agriculture due to its low consumption efficiency and overuse of available resources is water management to meet the water needs of crops in arid areas where water resources are limited, and estimating the water needs of plants is essential. In this study, FAO Penman Montith method was used to estimate the evapotranspiration potential of Northeast Iran, and ArcGIS software was used to zonation of evapotranspiration. The data required for this study were collected from 15 meteorological stations affiliated to the Meteorological Organization located in Khorasan Province (Razavi, jonubi, Shomali). These data are for the years 1999 to 2019 and include daily maximum and minimum values of air temperature, relative humidity, sunshine hours and wind speed. Days with incomplete data were excluded from analysis in this study. The results of this study showed that the rate of evapotranspiration on average days of the year varies from 0 to 6.9 mm per day and the highest evapotranspiration in July (134.4) mm per month and the lowest evapotranspiration in January (18.7) mm has occurred in the month. Potential evapotranspiration zoning in ArcGIS software environment showed that the highest evapotranspiration was in the southwest of the study area (Tabas) and the lowest was in the northeast of the study area (Quchan and Bojnourd).