Scale effect on hydraulic conductivity and solute transport: Small and large-scale laboratory experiments and field experiments

Hydraulic conductivity (K), dispersivity (α) and partition coefficient (Kd) can change according to the measurement support (scale) and that is referred to as scale effect. However, there is no clear consensus about the behavior of these parameters with the change in the scale. Comparison between results obtained in different support of measurements in the field and in the laboratory can promote the discussion about scale effects on K, α, and Kd, and contribute to understanding how these parameters behave with the change in the scale of measurement, the main objectives of the present paper. Small and large-scale laboratory tests using undisturbed soil samples and field experiments at different scales were performed. Results show that for the same measurement condition, K, α, and Kd increase with scale in all studied magnitudes. Caution should be taken when using K, α, and Kd values in numerical models with no concern about the scale effect. The lack of consideration of the difference of scale between field and laboratory measurements and numerical model may compromise the reliability of the predictions and misrepresent the responses.