Integrating variations in the soil chloride profile and evaporativity for in-situ estimation of evaporation in arid zones: an application in south-eastern Morocco; [Utilisation des variations des profils de chlorure dans les sols et de la tendance d’évaporation pour l’estimation in situ de l’évaporation en zone aride: application au sud-est du Maroc]; [Integrando variações no perfil de cloreto no solo e evaporatividade para estimativa in-situ de evaporação em zonas áridas: uma aplicação no sudeste do Marrocos]; [La integración de las variaciones de cloruro y de la demanda evaporativa en el perfil del suelo para la estimación in situ de la evaporación en las zonas áridas: una aplicación en el sureste de Marruecos]

In arid regions, knowledge of the evaporation rate from the water table is essential for appropriate management of scarce resources and to prevent land degradation. Soil chloride profiles in the unsaturated zone of a bare soil in an arid area of south-eastern Morocco were used to assess the evaporation flux, using chloride inventories in conjunction with evaporative demand. Moisture fluxes were calculated from measured chloride concentrations on the basis of a steady-state flow model. The chloride profiles displayed large variations in concentrations and had (1) low chloride concentrations near the soil surface, (2) maximum chloride concentrations at depths of 11–14 cm beneath the soil surface, respectively in July and February, and (3) gradually decreasing chloride concentrations while depth increased below these peaks. Evaporative demands were found to be inversely proportional to the depth of evaporation fronts and proportional to evaporation fluxes. In addition, the evaporation along the profiles seems to be controlled by the soil composition and texture. The investigation of chloride profiles in February and July enabled the determination of a value for annual evaporation (∼30 mm), which is in good agreement with the value estimated by the Allison-Barnes type model (∼32 mm). © 2016, Springer-Verlag Berlin Heidelberg.