Journal of Watershed Management Research

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Shirmohammad-Aliakbarkhani Z, Saberali S F. (2021). Sensitivity Analysis of the Reference Evapotranspiration to Meteorological Parameters in Khorasan Razavi Province. J Watershed Manage Res. 12(23), 260-272. doi:10.52547/jwmr.12.23.260
URL: http://jwmr.sanru.ac.ir/article-1-1090-en.html

Accurate estimation of reference crop evapotranspiration (ETo) is important in hydrological studies and water resource management that can influence the planning and policies for optimal allocation of agricultural water resources. For this purpose, in the present study, sensitivity analysis was employed to evaluate the effects of the changes in meteorological parameters (vapor pressure deficit (VPD), Mean Temperature (Tmean), net solar radiation (Rn), wind speed (u) and actual vapor pressure (ea)) on reference crop evapotranspiration (ETo) within the possible range of ±20% on a daily and growing season scale. ET0 was calculated by The Food and Agriculture Organization of the United Nations (FAO) 56 Penman-Monteith approach using long-term climate data from 13 meteorological stations of Khorasan Razavi province in northeast Iran. The sensitivity analysis indicated that ETo changes positively with vapor pressure deficit, mean temperature, net solar radiation and wind speed, while it changes negatively with actual vapor pressure. Also, over the whole period, ETo was most sensitive to vapor pressure deficit (VPD), followed by mean temperature (Tmean), net solar radiation (RN), actual vapor pressure (ea) and wind speed (WS). In the the warm growing season, ETo was most sensitive to vapor pressure deficit (VPD), followed by mean temperature (Tmean), net solar radiation (RN), wind speed (WS) and actual vapor pressure (ea) while, in the cool growing season, ETo was most sensitive to vapor pressure deficit (VPD), followed by actual vapor pressure (ea), Mean Temperature (Tmean), net solar radiation (RN) and wind speed (WS). The results showed that the sensitivity of ETo in different stations and different growth periods is different. The findings of this study showed that the importance of effective parameters on the reference crop evapotranspiration (ETo) was different between the hot and cool growing season of the region, which should be considered in sustainable planning of water resources and management of agriculture in Khorasan Razavi regions for development of adaptation strategies in arid climatic conditions.