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Estimation of actual evapotranspiration and crop coefficient in the REMENDHUS area, Spain

Gonzales Amaya, Andres Saul (2010) Estimation of actual evapotranspiration and crop coefficient in the REMENDHUS area, Spain.

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Abstract:The determination of the frequency and amount of irrigation water supply is necessary for sustainable development and water management. The estimation of the evapotranspiration (ET) is important for the water management in agricultural lands. The study area, REMENDHUS network in Spain, presents a high percent of agricultural land and its condition of semi arid Mediterranean region makes important the research and improvement of calculation the actual ET and crop coefficients (Kc) factors on this region. The one dimensional model, Hydrus-1D, and field soil moisture (SM) measurements are used to determinate the daily actual ET over some specific crops typical for the area (wheat, sunflower, sugar beet and onion). Later a remote sensing (RS) model, SEBS, is used to determinate the daily actual ET and then compare with the outputs of Hydrus-1D to see the applicability of RS method to the area. The water content predicted by Hydrus-1D matches very well in all 9 modelling runs during the years 2006 to 2009. The percentages of prediction vary between 72 and 92%. The actual ET predicted presents a realistic performance with values ranging between 0.02 and 4.18 mm/day after rain or irrigation. On the other hand SEBS4ILWIS is used in 8 MODIS images (1x1 km final resolution) producing considerable high values of actual ET (values between 1.11 and 8.71 mm/day) overestimating the daily actual ET. An analysis on these results is also suggested. Due to the good trend and high percent of prediction by Hydrus-1D the actual ET of this model is assumed adequate to carry out the calculation of the crop coefficients (Kc). Once calculated the new Kc for some specific crop on a specific date it is compared with the literature of FAO 56 guidelines. The Kc values obtained in this research follow the trend dictated in the literature, as during the initial and final stages the Kc values are low, but during the middle season the Kc shows higher. The crop coefficient for sunflower and wheat show an agreement with the values offered by FAO at least for the days with Ks equal to 1 or near to it (4 and 6 days respectively). On the other hand there is just 1 day available for onion and sugar beet so is more complex to come up with a general conclusion.
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
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