PET-Measurements of Tracer Distribution in the Model Soil Column

2 PET-Measurements of Tracer Distribution in the Model Soil Column 

The tracer distribution in two column cross sections measured 30 min after the impuls input is represented in Fig. 2.3. The largest mean concentration was measured at this time in the cross section 10.25 cm. The same concentration was measured in a small region in the cross section 21.5 cm. On basis of these dates the flow velocities could be estimated. The mean velocity was 0.0055 cm/s, but in a limited part of the cross section the flow velocity was 0.01 cm/s. 

Measurements of the same cross section at different times also give informations for the velocity distribution (Fig. 2.4). A flow velocity of 0.01 cm/s can be estimated 

Hydrodynamic problems of the entrance zone of soil columns are shown in Fig. 2.6. The tracer concentration shows a strong influence of wall flow in the entrance zone. The parabolic concentration profil, which is an essential condition for the validity of the dispersion model, developes only after a longer distance from the column bottom. 

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