Paper Information

Journal:   IRANIAN JOURNAL OF SOIL AND WATERS SCIENCES   2001 , Volume 15 , Number 2; Page(s) 0 To 0.
 
Paper: 

COMPARISON OF THREE SOLUTE TRANSPORT MODELS USING BROMIDE AS A TRACER

 
 
Author(s):  SHABANPOOR -
 
* 
 
Abstract: 
Simulation of solute transport in soil profile has many applications in agricultural and environmental problem such as management of plant nutrients, transport of pollutants and reclamation of saline soils. The objective of this study was to compare simulated results from three models with measurements of solute transport in a field planted with corn, wheat and alfalfa. Potassium bromide (300 kg/ha) was applied uniformly to the soil surface and then 1.5 cm of water was sprinkled over the plots in first and second year.
Plots were leached 8 times during the first year (each time with 8.5 cm of water) and 9 times in the second year (each time with 10 cm of water). Soli samples were collected from 0-30, 30-60, 60-90 and 90-120 cm depths two days after each application of water. Bromide concentration in soil samples were measured using an ion selective electrode. Moisture content in each plot was also measured using a neutron meter to a depth of 120 cm. Net application of water was based on the calculated evaporation loss from the soil profile.
CXTFIT code and three models of Regional Stochastic model (RSM), Convective -Dispersive Equation (CDE) and Transfer Function Model (TFM) were used to simulate leaching of water application under field conditions. The results showed that after addition of 25 cm of water 30% of bromide were leached out from the top 50 cm of soil in all plots in first year and control plots in second year but in second year 47,67 and 70% of bromide were leached out from the top 50 cm of soil in corn, wheat and alfalfa plots, respectively.
The RSM, TFM and CDE models showed a reasonable estimates for bromide leaching and storage in soils. In TFM model,the effects of dispersivity is not considered. Thus, the close estimation of RSM and TFM shows that the effect of dispersivity as compared with flow velocity on transport of bromide in soils is insignificant. The differences in simulated results were acceptable, since spatial variations in soil characteristics are unavoidable. Using the simpler TFM model in practical situations and RSM model in research projects is recommended
 
Keyword(s): REGIONAL STOCHASTIC MODEL, CONVECTIVE -DISPERSIVE EQUATION, TRANSFER FUNCTION MODEL, DISPERSIVITY
 
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