Effects of hydraulic and medium characteristics on solute transfer to surface runoff

A two-stage scouring-based model including two parameters for each stage, the ultimate scoured depth and rate of change of scoured depth, was developed to describe solute transfer to surface runoff. While the first stage is a quick decrease of mass loss of solute to surface runoff, the second stage is a slow one. An experimental flume with a medium packed bed was designed. Four different sizes of glass beads were chosen to be the media and saturated with uniform concentration (20000 ppm) of potassium chloride solution before runoff occurred. In a series of experiments, runoff was passed at varied flow rate, velocities, and depths over the medium bed. Runoff samples were taken at the end of flume and the concentration of potassium chloride analysed. By use of this model, the dimensionless ultimate scoured depth and the dimensionless rate of change of each stage were investigated. The results showed that the Reynolds number within media and the relative length were two important factors affecting mass loss of chemicals.