Abstract
Abstract. The impact of climate change and its relation with evapotranspiration was evaluated in the Duero River Basin (Spain). The study shows possible future situations 50 yr from now from the reference evapotranspiration (ETo). The maximum temperature (Tmax), minimum temperature (Tmin), dew point (Td), wind speed (U) and net radiation (Rn) trends during the 1980–2009 period were obtained and extrapolated with the FAO-56 Penman-Montheith equation to estimate ETo. Changes in stomatal resistance in response to increases in CO2 were also considered. Four scenarios were done, taking the concentration of CO2 and the period analyzed (annual or monthly) into consideration. The scenarios studied showed the changes in ETo as a consequence of the annual and monthly trends in the variables Tmax, Tmin, Td, U and Rn with current and future CO2 concentrations (372 ppm and 550 ppm). The future ETo showed increases between 118 mm (11 %) and 55 mm (5 %) with respect to the current situation of the river basin at 1042 mm. The months most affected by climate change are May, June, July, August and September, which also coincide with the maximum water needs of the basin's crops.
Highlights
The combination of two separate processes, where water is lost from the soil surface and from surface leaves by evaporation and from crops by transpiration, is referred to as evapotranspiration (ET)
In the Northern Hemisphere, the air temperature will increase by 0.3 ◦C per decade from 1979 through 2005 (Hansen et al, 2001; Smith and Reynolds, 2005; Brohan et al, 2006; Lugina et al, 2007)
According to Ceballos-Barbancho et al (2008), the Duero river basin has a clear trend towards higher temperatures with a mean increase of 0.58 ◦C decade−1 between 1973 and 2005
Summary
The combination of two separate processes, where water is lost from the soil surface and from surface leaves by evaporation and from crops by transpiration, is referred to as evapotranspiration (ET). Climatic parameters such as rainfall, wind speed, radiation, air temperature and air humidity affect the crop water requirements. In Spain the annual daily means temperatures have increased by 0.48 ◦C per decade from 1973 through 2005 (Brunet et al, 2007). According to Ceballos-Barbancho et al (2008), the Duero river basin has a clear trend towards higher temperatures with a mean increase of 0.58 ◦C decade−1 between 1973 and 2005
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