Soil water balance correction due to light rainfall, dew and fog in Ebro river basin (Spain)

• Published in: Agricultural water management 2016-05, Vol.170, p.61-67
• Main Authors: Moratiel, R., Martínez-Cob, A., Tarquis, A.M., Snyder, R.L.
• Format: Article
• Language: English
• Subjects: Canopies; Dew; Estimates; Evaporation; Evapotranspiration; Fog; Light rainfall; Rainfall; Soil (material); Soil Water Balance; Surface water
• ISSN: 0378-3774; 1873-2283
• DOI: 10.1016/j.agwat.2015.12.013

•We evaluate the methodology used to estimate the contribution of fog, dew or light rainfall to crop water use.•The method is based on the time of day when dew deposition, fog interception, or rainfall initial abstraction mostly dries from the plant foliage.•This study uses data from the Ebro River Basin to further evaluate the method proposed by Moratiel et al. (2013) for California to see if the method can be universally applied or if it only works in California.•We found that the California model also works in the Ebro River Basin in Spain.•Accuracy of the method depends mainly on the estimation of the time when the canopy dries. Accumulated daily crop evapotranspiration (ETc) generally provides good estimates of cumulative soil water depletion between irrigation of well drained soils. If the canopy is wet due to fog, dew, or light rainfall, however, energy contribution to surface evaporation will reduce transpiration and hence soil water losses. When surface evaporation occurs, the ETc overestimates the soil water depletion by an amount approximately equal to the surface water evaporation. Moratiel et al. (2013) proposed a method to estimate the contribution of surface water to ETc based on the time of canopy drying. The first method assessment was done with California data, and this evaluation was conducted in the Ebro basin, Spain, to appraise the method in a higher latitude in area with a somewhat different climate. Differences between the California and Spain corrected models were less than 10% and depended mainly on the time of canopy drying. The comparison showed that the model is robust and useful to estimate the fraction (F) of ETc coming from the soil under dew, light rainfall, and fog conditions.