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Abstract of the Article

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A Study on the Effect of Global Warming on Increasing Agricultural Water Use

Authors:
[ Farshi ] - Scientific board member of soil and water research institute of Iran
[ Emdad ] - Scientific board member of soil and water research institute of Iran

Abstract:

Global warming, which is expected to continue in the future, increases evaporative demand of the weather and potential vapotranspirationConsequently, it increases agricultural water use. Since most parts of Iran are situated in arid climatic zone with limited water resources and while the agricultural sector is the main consumer of water in the country (more than 85 percent) so this increase of water demandcould have important effects on the availability of water resources, as well as agricultural crop production, which must be considered in the country wide planning for water resources management. In this paper, it is attempted to study and determine the effect of increasing mean yearly temperature on the crop potential evapotranspiration in three main arid climates of the country, namely high arid cold i.e. Esfahan. high arid temperate i.e. Yazd and semi-arid cold i.e. Arak. This study was carried out in four steps,(l) to determine the potential evapotranspiration of reference crop (ETo) using CROPWAT computer model with long term meteorological data such as air temperature, humidity, wind speed and sunshine hours,(2) to determine the relationship and coefficient of correlation between the variation of air temperature with other meteorological parameters, (3) increasing 1,2,3,4 degree C'to the mean annual air temperature and censidering ,this increment in the other meteorological parameters which is affected at the evapotranspiration where its correlation coefficient is r > 0.5,(4) calculation of the potential evapotranspiration with increased air temperature and other modified meteorological data. Finally, the relative increments of the crop water requirements in the study of climate were determined. The results indicated that in the high arid cold and temperate climates, increasing air temperature up to 2 degrees C increases crop water requirements by 7% for each degree C, Thereafter this increment changes to 10% in high arid cold climate and 5% in high arid temperate climate. In the semi arid cold climate, the increase in crop water requirements for temperature rise up to 3 degree is and after wards it reaches 5%

Keywords:

global warming, evapotranspiration, crop water requirements, arid zone, greenhouse effects.