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Modeling solute transport by DLA in soils of northeastern Egypt.

Hamed YA, Yasuda H, Persson M, Berndtsson R, Wang XP - PLoS ONE (2015)

Bottom Line: The best fit was obtained with a specific combination of directional random walk probabilities Pu, Pd, Pr, and Pl for each plot (correlation 0.97-0.99).To account for soil layers with different hydraulic properties a two layer DLA model was developed.The overall results showed that spatial variability resulting from solute transport for the investigated soils can be modeled using a DLA approach.

View Article: PubMed Central - PubMed

Affiliation: Civil Engineering Department, Faculty of Engineering, Port Said University, Port Fouad Port Said, Egypt.

ABSTRACT
Arid soils in Egypt display large variability in solute transport properties, causing problems in soil management. To characterize this variability, dye infiltration experiments were conducted on four plots representing three main soil types in northeastern Egypt. The plots represented both cultivated and uncultivated land use. The observed dye patterns displayed a large variability and especially the clay soils indicated a high degree of preferential flow. The loamy sand and sandy soils displayed a more uniform dye distribution indicating more homogeneous soil properties. The observed dye patterns were modeled using a diffusion limited aggregation (DLA) model. The DLA is a random walk model where model parameters can be optimized using genetic algorithms (GA). The DLA model reproduced the observed dye patterns for all soils in an excellent way. The best fit was obtained with a specific combination of directional random walk probabilities Pu, Pd, Pr, and Pl for each plot (correlation 0.97-0.99). To account for soil layers with different hydraulic properties a two layer DLA model was developed. For all plots the Pu (upward random walk probability) was higher for the upper more homogeneous soil layer. The overall results showed that spatial variability resulting from solute transport for the investigated soils can be modeled using a DLA approach.

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Related in: MedlinePlus

Example of three successive dye pattern sections from each plot [10].
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pone.0119943.g004: Example of three successive dye pattern sections from each plot [10].

Mentions: Fig. 4 shows typical black and white images for each plot representing four successive vertical sections. Dye patterns for the remaining vertical sections were similar to those presented in the figure. Fig. 4 shows that strongest heterogeneous dye stained pattern was found in Plots 1 and 2 (natural and cultivated clay soil) as compared to the more homogeneous Plots 3 and 4 (loamy sand and sandy soil). Clayey soils in arid environments usually display strong heterogeneity because of crack formation due to repeated wetting and drying processes. A similar strong heterogeneity of solute transport for clayey soils was reported by [25,8,9]. Recall that the difference between Plots 1 and 2 is that the latter one had been cultivated. Since the top layer is made more homogeneous by agricultural activities such as plowing, cultivating, and seeding, the dye pattern also becomes somewhat more homogeneous. For Plot 1, the average dye infiltration depth was 0.36 m and the maximum depth was 0.47 m.


Modeling solute transport by DLA in soils of northeastern Egypt.

Hamed YA, Yasuda H, Persson M, Berndtsson R, Wang XP - PLoS ONE (2015)

Example of three successive dye pattern sections from each plot [10].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4366080&req=5

pone.0119943.g004: Example of three successive dye pattern sections from each plot [10].
Mentions: Fig. 4 shows typical black and white images for each plot representing four successive vertical sections. Dye patterns for the remaining vertical sections were similar to those presented in the figure. Fig. 4 shows that strongest heterogeneous dye stained pattern was found in Plots 1 and 2 (natural and cultivated clay soil) as compared to the more homogeneous Plots 3 and 4 (loamy sand and sandy soil). Clayey soils in arid environments usually display strong heterogeneity because of crack formation due to repeated wetting and drying processes. A similar strong heterogeneity of solute transport for clayey soils was reported by [25,8,9]. Recall that the difference between Plots 1 and 2 is that the latter one had been cultivated. Since the top layer is made more homogeneous by agricultural activities such as plowing, cultivating, and seeding, the dye pattern also becomes somewhat more homogeneous. For Plot 1, the average dye infiltration depth was 0.36 m and the maximum depth was 0.47 m.

Bottom Line: The best fit was obtained with a specific combination of directional random walk probabilities Pu, Pd, Pr, and Pl for each plot (correlation 0.97-0.99).To account for soil layers with different hydraulic properties a two layer DLA model was developed.The overall results showed that spatial variability resulting from solute transport for the investigated soils can be modeled using a DLA approach.

View Article: PubMed Central - PubMed

Affiliation: Civil Engineering Department, Faculty of Engineering, Port Said University, Port Fouad Port Said, Egypt.

ABSTRACT
Arid soils in Egypt display large variability in solute transport properties, causing problems in soil management. To characterize this variability, dye infiltration experiments were conducted on four plots representing three main soil types in northeastern Egypt. The plots represented both cultivated and uncultivated land use. The observed dye patterns displayed a large variability and especially the clay soils indicated a high degree of preferential flow. The loamy sand and sandy soils displayed a more uniform dye distribution indicating more homogeneous soil properties. The observed dye patterns were modeled using a diffusion limited aggregation (DLA) model. The DLA is a random walk model where model parameters can be optimized using genetic algorithms (GA). The DLA model reproduced the observed dye patterns for all soils in an excellent way. The best fit was obtained with a specific combination of directional random walk probabilities Pu, Pd, Pr, and Pl for each plot (correlation 0.97-0.99). To account for soil layers with different hydraulic properties a two layer DLA model was developed. For all plots the Pu (upward random walk probability) was higher for the upper more homogeneous soil layer. The overall results showed that spatial variability resulting from solute transport for the investigated soils can be modeled using a DLA approach.

Show MeSH
Related in: MedlinePlus