Determination of Dispersivity in A Laboratory Soil Column
In this study, a laboratory soil column experiment was carried out for estimating the dispersivity in sandy loam soil by the inversion of the Advection Dispersion Equation. An 89 cm deep and 15 cm diameter cylindrical column was filled with sandy loam soil in such a way that the bulk density of the soil in field condition was strictly satisfied in the column. Potassium bromide was used as the conservative tracer in the study. The tracer concentration was allowed to pass through the column at a constant rate and the leachate collected at different time periods were tested for the concentration of bromide. The experiment was carried out until the relative concentration c c0 has reached 1. The calculated relative concentration was plotted against time for obtaining the observed breakthrough curve BTC . Another BTC was plotted using the analytical solution of Advection Dispersion Equation. The effective dispersion coefficient De value which gave the best fit between these two curves was chosen by trial and error method and the dispersivity of the soil was calculated De = v for a constant pore water velocity v . The dispersivity of the sandy loam soil under study was found to be 1.7 cm which matches well with the previous researches.
Dispersivity Advection Dispersion Equation, Effective dispersion coefficient, Laboratory soil column.
M. R. Namitha | V. Ravikumar