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a Instituto de Agricultura Sostenible, CSIC, Apartado 4084, 14080 Córdoba, Spain
b Universidad de Córdoba, Dpto. de Agronomía, Avda. Menéndez Pidal S/N, 14071 Córdoba, Spain
* Corresponding author (ag2gocaj{at}uco.es).
The Soil Conservation Service curve number methodology (SCS-CN) has been used in hydrological and crop models to evaluate the effects of soil management in olive (Olea europaea L. subsp. europaea) orchards on runoff, erosion, and water balance. To our knowledge, it has never been calibrated or validated for olive orchards. A physically based runoff model for olive orchards at a hillslope scale was used to generate rainfall–runoff relationships for different scenarios of soil type (four), tree size (two), tree spacing (two), antecedent soil moisture (three), and soil management (11) for a 140-m-long and 5% steep hillslope. The resulting relationships were used to derive the values of the curve number parameter, CNd, for the SCS-CN methodology. The resulting CNd values were validated using rainfall–runoff data for three different locations and different soil management. Predictions of daily runoff using CNd were compared with those made using CN values extracted from the standard SCS-CN tables, CNSCS. The derived CNd values presented a root mean square error in runoff predictions between 0.5 and 7.3 mm, and a model efficiency between 82 and 97%. The extracted CNSCS values presented a root mean square error in runoff predictions between 1.4 and 10.4 mm, and a model efficiency between –81 and 89%. Our analysis identified some issues in the hydrology of olive orchards where our understanding remains limited. Among them are the need for further validation of the derived CN values given the limited rainfall–runoff data, and the effect of soil management on soil properties and their temporal evolution.
Abbreviations: CN, curve number CNbf, curve number values developed through fitting to the observed runoff data CNd, curve number values derived for olive orchards from the physically based model CNSCS, curve number values extracted for olive orchards from the Soil Conservation Service curve number tables CNI, curve number for dry antecedent soil moisture content CNII, curve number for average antecedent soil moisture content CNIII, curve number for wet antecedent soil moisture content CC, cover crop soil management CT, conventional tillage soil management NT, no-till RR, random roughness SCS-CN, Soil Conservation Service curve number methodology
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