Evapotranspiration model selection for estimation of actual evaporation from bare soil,as required in annual potential groundwater recharge studies of a semi-arid foothill region |
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| Authors: | Seyed Adib Banimahd Ali Akbar Kamgar-Haghighi Shahrokh Zand-Parsa |
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| Institution: | Water Engineering Department, College of Agriculture, Shiraz University, Shiraz, Islamic Republic of Iran |
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| Abstract: | Improved evapotranspiration estimation is instrumental in annual potential recharge (Re) evaluations of semi-arid regions, in the context of the water balance approach. Complementary relationship areal evapotranspiration (CRAE) and advection–aridity (AA) and a general combination equation proposed by Granger and Gray (GG) were evaluated for the estimation of actual evaporation (Ea) from bare soil under occurrence of Re. Model capability was evaluated by utilizing data from lysimeter measurements during the hydrological years (2011–2012) and (2012–2013)]. Measured parameters included soil moisture (SM), rainfall and related meteorological data and Re (lysimeter output). All models with original parameters performed poorly during 2011–2012 and 2012–2013, underestimating annual Re values. The 2011–2012 data were used for model calibration, considering annual Ea criterion (I)] and cumulative Ea during the occurrence period of Re criterion(II)]. The calibrated CRAE model criterion (II)] produced the best simulation for Ea (NRMSE < 30%). The 2012–2013 data were used to validate the models, and the calibrated CRAE model produced acceptable results (NRMSE < 10%) in SM simulation (both criteria). But calibrated CRAE under criterion (II) provided the best estimation of annual Re (ΔQ < 6%). According to the results, CR models can produce acceptable estimation of annual Re, if initially calibrated utilizing criterion (II). |
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| Keywords: | actual evaporation potential groundwater recharge complementary relation foothill semi-arid |
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