Exchange-layer; Diffusion; Bromide;

el’s underlying conceptual basis is that near-surface soil chemicals are ejected into runoff by raindrop impact and chemicals deeper in the soil diffuse into this near-surface raindrop infiltration). Model parameters that could not be directly determined from the descrip-the results agreed well with measured solute concentrations in both runoff and soil-water via overland flow. ª 2007 Elsevier B.V. All rights reserved. Accurate, physically-based modeling of soil chemical trans-fer into runoff is essential for developing predictive non-on both the ejection of soil-water by raindrop impacts and the diffusion of deeper solutes into the near-surface rain-drop driven ‘‘exchange’ ’ layer. This finding was in strong contrast to many previously published models that either assumed a single process dominated the system or that multiple, interacting processes could by represented by using ‘‘effective’ ’ parameters (e.g. Frere et al., 1980