Impact of observation thresholds in the assessment of field-scale soil saturated hydraulic conductivity

•Impact of censored observations on Ks distribution parameter estimates is evaluated.•Role of temporal variation of rainfall in resolving the Ks field is demonstrated.•Recommendations are provided as to what constitutes a good calibration event. The soil saturated hydraulic conductivity (Ks) plays a key role in the partitioning of rainfall into runoff and infiltration. Field-scale variability of Ks is often represented as a lognormal random field, and its parameters are frequently estimated by calibrating areal-average infiltration models with infiltration observations obtained under natural/artificial rainfall conditions. Such observations are obtained in terms of censored moments as infiltration is controlled by only a fraction of the Ks random field during a rainfall event. In this study, the impact of such observations on the maximum likelihood estimates (MLE) of the Ks distribution parameters is evaluated. Based on the data from several rainfall-runoff events observed under natural conditions over an experimental field, the results demonstrate the role of temporal variation of rainfall in resolving the Ks field for a rainfall event. Validation results show that the performance of the MLEs is impacted by both the fraction of the Ks field resolved by a rainfall event and its capacity to capture the variability of Ks. Finally, recommendations are provided as to what constitutes a good calibration event. The impact of incorporating reliability of the calibration events in consolidating information was tested using an information-theoretic measure.